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Gallium is a chemical element with the symbolGa and atomic number 31. Discovered by FrenchchemistPaul-Émile Lecoq de Boisbaudran in 1875,^[6] Gallium is in group 13 of the periodic table and is similar to the other metals of the group (aluminium, indium, and thallium).

Elemental gallium is a soft, silvery metal at standard temperature and pressure. In its liquid state, it becomes silvery white. If too much force is applied, the gallium may fracture conchoidally. Since its discovery in 1875, gallium has widely been used to make alloys with low melting points. It is also used in semiconductors, as a dopant in semiconductor substrates.

The melting point of gallium is used as a temperature reference point. Gallium alloys are used in thermometers as a non-toxic and environmentally friendly alternative to mercury, and can withstand higher temperatures than mercury. An even lower melting point of −19 °C (−2 °F), well below the freezing point of water, is claimed for the alloy galinstan (62–⁠95% gallium, 5–⁠22% indium, and 0–⁠16% tin by weight), but that may be the freezing point with the effect of supercooling.

Gallium does not occur as a free element in nature, but as gallium(III) compounds in trace amounts in zinc ores (such as sphalerite) and in bauxite. Elemental gallium is a liquid at temperatures greater than 29.76 °C (85.57 °F), and will melt in a person's hands at normal human body temperature of 37.0 °C (98.6 °F).

Gallium is predominantly used in electronics. Gallium arsenide, the primary chemical compound of gallium in electronics, is used in microwave circuits, high-speed switching circuits, and infrared circuits. Semiconducting gallium nitride and indium gallium nitride produce blue and violet light-emitting diodes (LEDs) and diode lasers. Gallium is also used in the production of artificial gadolinium gallium garnet for jewelry. Gallium is considered a technology-critical element by the United States National Library of Medicine and Frontiers Media.^[7][8]

Gallium has no known natural role in biology. Gallium(III) behaves in a similar manner to ferric salts in biological systems and has been used in some medical applications, including pharmaceuticals and radiopharmaceuticals.

Physical properties[edit]

Elemental gallium is not found in nature, but it is easily obtained by smelting. Very pure gallium is a silvery blue metal that fractures conchoidally like glass. Gallium liquid expands by 3.10% when it solidifies; therefore, it should not be stored in glass or metal containers because the container may rupture when the gallium changes state. Gallium shares the higher-density liquid state with a short list of other materials that includes water, silicon, germanium, bismuth, and plutonium.^[9]

Gallium attacks most other metals by diffusing into the metal lattice. For example, it diffuses into the grain boundaries of aluminium-zincalloys^[10] and steel,^[11] making them very brittle. Gallium easily alloys with many metals, and is used in small quantities in the plutonium–gallium alloy in the plutonium cores of nuclear bombs to stabilize the plutonium crystal structure.^[12]

The melting point of gallium, at 302.9146 K (29.7646 °C, 85.5763 °F), is just above room temperature, and is approximately the same as the average summer daytime temperatures in Earth's mid-latitudes. This melting point (mp) is one of the formal temperature reference points in the International Temperature Scale of 1990 (ITS-90) established by the International Bureau of Weights and Measures (BIPM).^[13][14][15] The triple point of gallium, 302.9166 K (29.7666 °C, 85.5799 °F), is used by the US National Institute of Standards and Technology (NIST) in preference to the melting point.^[16]

The melting point of gallium allows it to melt in the human hand, and then solidify if removed. The liquid metal has a strong tendency to supercool below its melting point/freezing point: Ga nanoparticles can be kept in the liquid state below 90 K.^[17]Seeding with a crystal helps to initiate freezing. Gallium is one of the four non-radioactive metals (with caesium, rubidium, and mercury) that are known to be liquid at, or near, normal room temperature. Of the four, gallium is the only one that is neither highly reactive (rubidium and caesium) nor highly toxic (mercury) and can, therefore, be used in metal-in-glass high-temperature thermometers. It is also notable for having one of the largest liquid ranges for a metal, and for having (unlike mercury) a low vapor pressure at high temperatures. Gallium's boiling point, 2673 K, is more than eight times higher than its melting point on the absolute scale, the greatest ratio between melting point and boiling point of any element.^[18] Unlike mercury, liquid gallium metal wets glass and skin, along with most other materials (with the exceptions of quartz, graphite, and Teflon)^{[citation needed]}, making it mechanically more difficult to handle even though it is substantially less toxic and requires far fewer precautions. Gallium painted onto glass is a brilliant mirror.^[19] For this reason as well as the metal contamination and freezing-expansion problems, samples of gallium metal are usually supplied in polyethylene packets within other containers.

Gallium does not crystallize in any of the simple crystal structures. The stable phase under normal conditions is orthorhombic with 8 atoms in the conventional unit cell. Within a unit cell, each atom has only one nearest neighbor (at a distance of 244 pm). The remaining six unit cell neighbors are spaced 27, 30 and 39 pm farther away, and they are grouped in pairs with the same distance.^[21] Many stable and metastable phases are found as function of temperature and pressure.^[22]

The bonding between the two nearest neighbors is covalent; hence Ga₂dimers are seen as the fundamental building blocks of the crystal. This explains the low melting point relative to the neighbor elements, aluminium and indium. This structure is strikingly similar to that of iodine and may form because of interactions between the single 4p electrons of gallium atoms, further away from the nucleus than the 4s electrons and the [Ar]3d¹⁰ core. This phenomenon recurs with mercury with its 'pseudo-noble-gas' [Xe]4f¹⁴5d¹⁰6s² electron configuration, which is liquid at room temperature.^[23] The 3d¹⁰ electrons do not shield the outer electrons very well from the nucleus and hence the first ionisation energy of gallium is greater than that of aluminium.^[9] Ga₂ dimers do not persist in the liquid state and liquid gallium exhibits a complex low-coordinated structure in which each gallium atom is surrounded by 10 others, compared to values of 11-12 typical of most liquid metals.^[24][25]

The physical properties of gallium are highly anisotropic, i.e. have different values along the three major crystallographical axes a, b, and c (see table), producing a significant difference between the linear (α) and volume thermal expansion coefficients. The properties of gallium are strongly temperature-dependent, particularly near the melting point. For example, the coefficient of thermal expansion increases by several hundred percents upon melting.^[20]

Isotopes[edit]

Gallium has 31 known isotopes, ranging in mass number from 56 to 86. Only two isotopes are stable and occur naturally, gallium-69 and gallium-71. Gallium-69 is more abundant: it makes up about 60.1% of natural gallium, while gallium-71 makes up the remaining 39.9%. All the other isotopes are radioactive, with gallium-67 being the longest-lived (half-life 3.261 days). Isotopes lighter than gallium-69 usually decay through beta plus decay (positron emission) or electron capture to isotopes of zinc, although the lightest few (with mass numbers 56 through 59) decay through prompt proton emission. Isotopes heavier than gallium-71 decay through beta minus decay (electron emission), possibly with delayed neutron emission, to isotopes of germanium, while gallium-70 can decay through both beta minus decay and electron capture. Gallium-67 is unique among the light isotopes in having only electron capture as a decay mode, as its decay energy is not sufficient to allow positron emission.^[26] Gallium-67 and gallium-68 (half-life 67.7 min) are both used in nuclear medicine.

Chemical properties[edit]

Gallium is found primarily in the +3 oxidation state. The +1 oxidation state is also found in some compounds, although it is less common than it is for gallium's heavier congeners indium and thallium. For example, the very stable GaCl₂ contains both gallium(I) and gallium(III) and can be formulated as Ga^IGa^IIICl₄; in contrast, the monochloride is unstable above 0 °C, disproportionating into elemental gallium and gallium(III) chloride. Compounds containing Ga–Ga bonds are true gallium(II) compounds, such as GaS (which can be formulated as Ga₂⁴⁺(S²⁻)₂) and the dioxan complex Ga₂Cl₄(C₄H₈O₂)₂.^[27]

Aqueous chemistry[edit]

Strong acids dissolve gallium, forming gallium(III) salts such as Ga(NO
₃)
₃ (gallium nitrate). Aqueous solutions of gallium(III) salts contain the hydrated gallium ion, [Ga(H
₂O)
₆]³⁺
.^[28]: 1033Gallium(III) hydroxide, Ga(OH)
₃, may be precipitated from gallium(III) solutions by adding ammonia. Dehydrating Ga(OH)
₃ at 100 °C produces gallium oxide hydroxide, GaO(OH).^{[29]: 140–141}

Alkaline hydroxide solutions dissolve gallium, forming gallate salts (not to be confused with identically named gallic acid salts) containing the Ga(OH)⁻
₄ anion.^{[30][28]: 1033 [31]} Gallium hydroxide, which is amphoteric, also dissolves in alkali to form gallate salts.^[29]: 141 Although earlier work suggested Ga(OH)³⁻
₆ as another possible gallate anion,^[32] it was not found in later work.^[31]

Oxides and chalcogenides[edit]

Gallium reacts with the chalcogens only at relatively high temperatures. At room temperature, gallium metal is not reactive with air and water because it forms a passive, protective oxide layer. At higher temperatures, however, it reacts with atmospheric oxygen to form gallium(III) oxide, Ga
₂O
₃.^[30] Reducing Ga
₂O
₃ with elemental gallium in vacuum at 500 °C to 700 °C yields the dark brown gallium(I) oxide, Ga
₂O.^[29]: 285Ga
₂O is a very strong reducing agent, capable of reducing H
₂SO
₄ to H
₂S.^[29]: 207 It disproportionates at 800 °C back to gallium and Ga
₂O
₃.^[33]

Gallium(III) sulfide, Ga
₂S
₃, has 3 possible crystal modifications.^[33]: 104 It can be made by the reaction of gallium with hydrogen sulfide (H
₂S) at 950 °C.^[29]: 162 Alternatively, Ga(OH)
₃ can be used at 747 °C:^[34]

2 Ga(OH)
₃ + 3 H
₂S → Ga
₂S
₃ + 6 H
₂O

Reacting a mixture of alkali metal carbonates and Ga
₂O
₃ with H
₂S leads to the formation of thiogallates containing the [Ga
₂S
₄]²⁻
anion. Strong acids decompose these salts, releasing H
₂S in the process.^{[33]: 104–105} The mercury salt, HgGa
₂S
₄, can be used as a phosphor.^[35]

Gallium also forms sulfides in lower oxidation states, such as gallium(II) sulfide and the green gallium(I) sulfide, the latter of which is produced from the former by heating to 1000 °C under a stream of nitrogen.^[33]: 94

The other binary chalcogenides, Ga
₂Se
₃ and Ga
₂Te
₃, have the zincblende structure. They are all semiconductors but are easily hydrolysed and have limited utility.^[33]: 104

Nitrides and pnictides[edit]

Gallium reacts with ammonia at 1050 °C to form gallium nitride, GaN. Gallium also forms binary compounds with phosphorus, arsenic, and antimony: gallium phosphide (GaP), gallium arsenide (GaAs), and gallium antimonide (GaSb). These compounds have the same structure as ZnS, and have important semiconducting properties.^[28]: 1034 GaP, GaAs, and GaSb can be synthesized by the direct reaction of gallium with elemental phosphorus, arsenic, or antimony.^[33]: 99 They exhibit higher electrical conductivity than GaN.^[33]: 101 GaP can also be synthesized by reacting Ga
₂O with phosphorus at low temperatures.^[36]

Gallium forms ternary nitrides; for example:^[33]: 99

Li
₃Ga + N
₂ → Li
₃GaN
₂

Similar compounds with phosphorus and arsenic are possible: Li
₃GaP
₂ and Li
₃GaAs
₂. These compounds are easily hydrolyzed by dilute acids and water.^[33]: 101

Halides[edit]

Gallium(III) oxide reacts with fluorinating agents such as HF or F
₂ to form gallium(III) fluoride, GaF
₃. It is an ionic compound strongly insoluble in water. However, it dissolves in hydrofluoric acid, in which it forms an adduct with water, GaF
₃·3H
₂O. Attempting to dehydrate this adduct forms GaF
₂OH·nH
₂O. The adduct reacts with ammonia to form GaF
₃·3NH
₃, which can then be heated to form anhydrous GaF
₃.^{[29]: 128–129}

Gallium trichloride is formed by the reaction of gallium metal with chlorine gas.^[30] Unlike the trifluoride, gallium(III) chloride exists as dimeric molecules, Ga
₂Cl
₆, with a melting point of 78 °C. Eqivalent compounds are formed with bromine and iodine, Ga
₂Br
₆ and Ga
₂I
₆.^[29]: 133

Like the other group 13 trihalides, gallium(III) halides are Lewis acids, reacting as halide acceptors with alkali metal halides to form salts containing GaX⁻
₄ anions, where X is a halogen. They also react with alkyl halides to form carbocations and GaX⁻
₄.^{[29]: 136–137}

When heated to a high temperature, gallium(III) halides react with elemental gallium to form the respective gallium(I) halides. For example, GaCl
₃ reacts with Ga to form GaCl:

2 Ga + GaCl
₃ ⇌ 3 GaCl (g)

At lower temperatures, the equilibrium shifts toward the left and GaCl disproportionates back to elemental gallium and GaCl
₃. GaCl can also be produced by reacting Ga with HCl at 950 °C; the product can be condensed as a red solid.^[28]: 1036

Gallium(I) compounds can be stabilized by forming adducts with Lewis acids. For example:

GaCl + AlCl
₃ → Ga⁺
[AlCl
₄]⁻

The so-called 'gallium(II) halides', GaX
₂, are actually adducts of gallium(I) halides with the respective gallium(III) halides, having the structure Ga⁺
[GaX
₄]⁻
. For example:^{[30][28]: 1036 [37]}

GaCl + GaCl
₃ → Ga⁺
[GaCl
₄]⁻

Hydrides[edit]

Like aluminium, gallium also forms a hydride, GaH
₃, known as gallane, which may be produced by reacting lithium gallanate (LiGaH
₄) with gallium(III) chloride at −30 °C:^[28]: 1031

3 LiGaH
₄ + GaCl
₃ → 3 LiCl + 4 GaH
₃

In the presence of dimethyl ether as solvent, GaH
₃ polymerizes to (GaH
₃)
_n. If no solvent is used, the dimer Ga
₂H
₆ (digallane) is formed as a gas. Its structure is similar to diborane, having two hydrogen atoms bridging the two gallium centers,^[28]: 1031 unlike α-AlH
₃ in which aluminium has a coordination number of 6.^[28]: 1008

Gallane is unstable above −10 °C, decomposing to elemental gallium and hydrogen.^[38]

Organogallium compounds[edit]

Organogallium compounds are of similar reactivity to organoindium compounds, less reactive than organoaluminium compounds, but more reactive than organothallium compounds.^[39] Alkylgalliums are monomeric. Lewis acidity decreases in the order Al > Ga > In and as a result organogallium compounds do not form bridged dimers as organoaluminum compounds do. Organogallium compounds are also less reactive than organoaluminum compounds. They do form stable peroxides.^[40] These alkylgalliums are liquids at room temperature, having low melting points, and are quite mobile and flammable. Triphenylgallium is monomeric in solution, but its crystals form chain structures due to weak intermolecluar Ga···C interactions.^[39]

Gallium trichloride is a common starting reagent for the formation of organogallium compounds, such as in carbogallation reactions.^[41] Gallium trichloride reacts with lithium cyclopentadienide in diethyl ether to form the trigonal planar gallium cyclopentadienyl complex GaCp₃. Gallium(I) forms complexes with arene ligands such as hexamethylbenzene. Because this ligand is quite bulky, the structure of the [Ga(η⁶-C₆Me₆)]⁺ is that of a half-sandwich. Less bulky ligands such as mesitylene allow two ligands to be attached to the central gallium atom in a bent sandwich structure. Benzene is even less bulky and allows the formation of dimers: an example is [Ga(η⁶-C₆H₆)₂] [GaCl₄]·3C₆H₆.^[39]

History[edit]

In 1871, the existence of gallium was first predicted by Russian chemist Dmitri Mendeleev, who named it 'eka-aluminium' from its position in his periodic table. He also predicted several properties of eka-aluminium that correspond closely to the real properties of gallium, such as its density, melting point, oxide character, and bonding in chloride.^[42]

Mendeleev further predicted that eka-aluminium would be discovered by means of the spectroscope, and that metallic eka-aluminium would dissolve slowly in both acids and alkalis and would not react with air. He also predicted that M₂O₃ would dissolve in acids to give MX₃ salts, that eka-aluminium salts would form basic salts, that eka-aluminium sulfate should form alums, and that anhydrous MCl₃ should have a greater volatility than ZnCl₂: all of these predictions turned out to be true.^[43]

Gallium was discovered using spectroscopy by French chemist Paul Emile Lecoq de Boisbaudran in 1875 from its characteristic spectrum (two violet lines) in a sample of sphalerite.^[44] Later that year, Lecoq obtained the free metal by electrolysis of the hydroxide in potassium hydroxide solution.^[45]

He named the element 'gallia', from LatinGallia meaning Gaul, after his native land of France. It was later claimed that, in a multilingual pun of a kind favoured by men of science in the 19th century, he had also named gallium after himself: 'Le coq' is French for 'the rooster' and the Latin word for 'rooster' is 'gallus'. In an 1877 article, Lecoq denied this conjecture.^[45]

Originally, de Boisbaudran determined the density of gallium as 4.7 g/cm³, the only property that failed to match Mendeleev's predictions; Mendeleev then wrote to him and suggested that he should remeasure the density, and de Boisbaudran then obtained the correct value of 5.9 g/cm³, that Mendeleev had predicted exactly.^[43]

From its discovery in 1875 until the era of semiconductors, the primary uses of gallium were high-temperature thermometrics and metal alloys with unusual properties of stability or ease of melting (some such being liquid at room temperature).

The development of gallium arsenide as a direct bandgap semiconductor in the 1960s ushered in the most important stage in the applications of gallium.^[19] In 1978, the electronics industry used gallium to fabricate light emitting diodes, photovoltaics and semiconductors, while the metals business used it,^[46] to reduce the melting point of alloys.^[47]

Occurrence[edit]

Gallium does not exist as a free element in the Earth's crust, and the few high-content minerals, such as gallite (CuGaS₂), are too rare to serve as a primary source.^[48] The abundance in the Earth's crust is approximately 16.9 ppm.^[49] This is comparable to the crustal abundances of lead, cobalt, and niobium. Yet unlike these elements, gallium does not form its own ore deposits with concentrations of > 0.1 wt.% in ore. Rather it occurs at trace concentrations similar to the crustal value in zinc ores,^[48][50] and at somewhat higher values (~ 50 ppm) in aluminium ores, from both of which it is extracted as a by-product. This lack of independent deposits is due to gallium's geochemical behaviour, showing no strong enrichment in the processes relevant to the formation of most ore deposits.^[48]

The United States Geological Survey (USGS) estimates that more than 1 million tons of gallium is contained in known reserves of bauxite and zinc ores.^[51][52] Some coal fluedusts contain small quantities of gallium, typically less than 1% by weight.^{[53][54][55][56]} However, these amounts are not extractable without mining of the host materials (see below). Thus, the availability of gallium is fundamentally determined by the rate at which bauxite, zinc ores (and coal) are extracted.

Production and availability[edit]

Gallium is produced exclusively as a by-product during the processing of the ores of other metals. Its main source material is bauxite, the chief ore of aluminium, but minor amounts are also extracted from sulfidic zinc ores (sphalerite being the main host mineral).^[57][58] In the past, certain coals were an important source.

During the processing of bauxite to alumina in the Bayer process, gallium accumulates in the sodium hydroxide liquor. From this it can be extracted by a variety of methods. The most recent is the use of ion-exchange resin.^[57] Achievable extraction efficiencies critically depend on the original concentration in the feed bauxite. At a typical feed concentration of 50 ppm, about 15% of the contained gallium is extractable.^[57] The remainder reports to the red mud and aluminium hydroxide streams. Gallium is removed from the ion-exchange resin in solution. Electrolysis then gives gallium metal. For semiconductor use, it is further purified with zone melting or single-crystal extraction from a melt (Czochralski process). Purities of 99.9999% are routinely achieved and commercially available.^[59]

Its by-product status means that gallium production is constrained by the amount of bauxite, sulfidic zinc ores (and coal) extracted per year. Therefore, its availability needs to be discussed in terms of supply potential. The supply potential of a by-product is defined as that amount which is economically extractable from its host materials per year under current market conditions (i.e. technology and price).^[60] Reserves and resources are not relevant for by-products, since they cannot be extracted independently from the main-products.^[61] Recent estimates put the supply potential of gallium at a minimum of 2,100 t/yr from bauxite, 85 t/yr from sulfidic zinc ores, and potentially 590 t/yr from coal.^[57] These figures are significantly greater than current production (375 t in 2016).^[62] Thus, major future increases in the by-product production of gallium will be possible without significant increases in production costs or price. The average price in for low-grade gallium was $120 per kilogram in 2016 and $135–140 per kilogram in 2017.^[63]

In 2017, the world's production of low-grade gallium was ca. 315 tons — an increase of 15% from 2016. China, Japan, South Korea, Russia, and Ukraine were the leading producers, while Germany ceased primary production of gallium in 2016. The yield of high-purity gallium was ca. 180 tons, mostly originating from China, Japan, Slovakia, UK and U.S. The 2017 world annual production capacity was estimated at 730 tons for low-grade and 320 tons for refined gallium.^[63]

China produced ca. 250 tons of low-grade gallium in 2016 and ca. 300 tons in 2017. It also accounted for more than half of global LED production.^[63]

Applications[edit]

Semiconductor applications dominate the commercial demand for gallium, accounting for 98% of the total. The next major application is for gadolinium gallium garnets.^[64]

Semiconductors[edit]

Extremely high-purity (>99.9999%) gallium is commercially available to serve the semiconductor industry. Gallium arsenide (GaAs) and gallium nitride (GaN) used in electronic components represented about 98% of the gallium consumption in the United States in 2007. About 66% of semiconductor gallium is used in the U.S. in integrated circuits (mostly gallium arsenide), such as the manufacture of ultra-high-speed logic chips and MESFETs for low-noise microwave preamplifiers in cell phones. About 20% of this gallium is used in optoelectronics.^[51]

Worldwide, gallium arsenide makes up 95% of the annual global gallium consumption.^[59] It amounted $7.5 billion in 2016, with 53% originating from cell phones, 27% from wireless communications, and the rest from automotive, consumer, fiber-optic, and military applications. The recent increase in GaAs consumption is mostly related to the emergence of 3G and 4Gsmartphones, which use 10 times more GaAs than older models.^[63]

Gallium arsenide and gallium nitride can also be found in a variety of optoelectronic devices which had a market share of $15.3 billion in 2015 and $18.5 billion in 2016.^[63]Aluminium gallium arsenide (AlGaAs) is used in high-power infrared laser diodes. The semiconductors gallium nitride and indium gallium nitride are used in blue and violet optoelectronic devices, mostly laser diodes and light-emitting diodes. For example, gallium nitride 405 nm diode lasers are used as a violet light source for higher-density Blu-ray Disc compact data disc drives.^[65]

Other major application of gallium nitride are cable television transmission, commercial wireless infrastructure, power electronics, and satellites. The GaN radio frequency device market alone was estimated at $370 million in 2016 and $420 million in 2016.^[63]

Multijunction photovoltaic cells, developed for satellite power applications, are made by molecular-beam epitaxy or metalorganic vapour-phase epitaxy of thin films of gallium arsenide, indium gallium phosphide, or indium gallium arsenide. The Mars Exploration Rovers and several satellites use triple-junction gallium arsenide on germanium cells.^[66] Gallium is also a component in photovoltaic compounds (such as copper indium gallium selenium sulfide Cu(In,Ga)(Se,S)₂) used in solar panels as a cost-efficient alternative to crystalline silicon.^[67]

Galinstan and other alloys[edit]

Gallium readily alloys with most metals, and is used as an ingredient in low-melting alloys. The nearly eutectic alloy of gallium, indium, and tin is a room temperature liquid used in medical thermometers. This alloy, with the trade-name Galinstan (with the '-stan' referring to the tin, stannum in Latin), has a low freezing point of −19 °C (−2.2 °F).^[68] It has been suggested that this family of alloys could also be used to cool computer chips in place of water, and is often used as a replacement for thermal paste in high-performance computing.^[69][70] Gallium alloys have been evaluated as substitutes for mercury dental amalgams, but these materials have yet to see wide acceptance.

Because gallium wets glass or porcelain, gallium can be used to create brilliant mirrors. When the wetting action of gallium-alloys is not desired (as in Galinstan glass thermometers), the glass must be protected with a transparent layer of gallium(III) oxide.^[71]

The plutonium used in nuclear weapon pits is stabilized in the δ phase and made machinable by alloying with gallium.^[72]

Biomedical applications[edit]

Although gallium has no natural function in biology, gallium ions interact with processes in the body in a manner similar to iron(III). Because these processes include inflammation, a marker for many disease states, several gallium salts are used (or are in development) as pharmaceuticals and radiopharmaceuticals in medicine. Interest in the anticancer properties of gallium emerged when it was discovered that ⁶⁷Ga(III) citrate injected in tumor-bearing animals localized to sites of tumor. Clinical trials have shown gallium nitrate to have antineoplastic activity against non-Hodgkin's lymphoma and urothelial cancers. A new generation of gallium-ligand complexes such as tris(8-quinolinolato)gallium(III) (KP46) and gallium maltolate has emerged.^[73]Gallium nitrate (brand name Ganite) has been used as an intravenous pharmaceutical to treat hypercalcemia associated with tumor metastasis to bones. Gallium is thought to interfere with osteoclast function, and the therapy may be effective when other treatments have failed.^[74]Gallium maltolate, an oral, highly absorbable form of gallium(III) ion, is an anti-proliferative to pathologically proliferating cells, particularly cancer cells and some bacteria that accept it in place of ferric iron (Fe³⁺). Researchers are conducting clinical and preclinical trials on this compound as a potential treatment for a number of cancers, infectious diseases, and inflammatory diseases.^[75]

When gallium ions are mistakenly taken up in place of iron(III) by bacteria such as Pseudomonas, the ions interfere with respiration, and the bacteria die. This happens because iron is redox-active, allowing the transfer of electrons during respiration, while gallium is redox-inactive.^[76][77]

A complex amine-phenol Ga(III) compound MR045 is selectively toxic to parasites resistant to chloroquine, a common drug against malaria. Both the Ga(III) complex and chloroquine act by inhibiting crystallization of hemozoin, a disposal product formed from the digestion of blood by the parasites.^[78][79]

Radiogallium salts[edit]

Gallium-67salts such as gallium citrate and gallium nitrate are used as radiopharmaceutical agents in the nuclear medicine imaging known as gallium scan. The radioactive isotope⁶⁷Ga is used, and the compound or salt of gallium is unimportant. The body handles Ga³⁺ in many ways as though it were Fe³⁺, and the ion is bound (and concentrates) in areas of inflammation, such as infection, and in areas of rapid cell division. This allows such sites to be imaged by nuclear scan techniques.^[80]

Gallium-68, a positron emitter with a half-life of 68 min, is now used as a diagnostic radionuclide in PET-CT when linked to pharmaceutical preparations such as DOTATOC, a somatostatin analogue used for neuroendocrine tumors investigation, and DOTA-TATE, a newer one, used for neuroendocrine metastasis and lung neuroendocrine cancer, such as certain types of microcytoma. Gallium-68's preparation as a pharmaceutical is chemical, and the radionuclide is extracted by elution from germanium-68, a synthetic radioisotope of germanium, in gallium-68 generators.^[81]

Other uses[edit]

Gallium is used for neutrino detection. Possibly the largest amount of pure gallium ever collected in a single spot is the Gallium-Germanium Neutrino Telescope used by the SAGE experiment at the Baksan Neutrino Observatory in Russia. This detector contains 55–57 tonnes (~9 cubic metres) of liquid gallium.^[84] Another experiment was the GALLEX neutrino detector operated in the early 1990s in an Italian mountain tunnel. The detector contained 12.2 tons of watered gallium-71. Solar neutrinos caused a few atoms of ⁷¹Ga to become radioactive ⁷¹Ge, which were detected. This experiment showed that the solar neutrino flux is 40% less than theory predicted. This deficit was not explained until better solar neutrino detectors and theories were constructed (see SNO).^[85]

Gallium is also used as a liquid metal ion source for a focused ion beam. For example, a focused gallium-ion beam was used to create the world's smallest book, Teeny Ted from Turnip Town.^[86] Another use of gallium is as an additive in glide wax for skis, and other low-friction surface materials.^[87]

A well-known practical joke among chemists is to fashion gallium spoons and use them to serve tea to unsuspecting guests, since gallium has a similar appearance to its lighter homolog aluminium. The spoons then melt in the hot tea.^[88]

Gallium in the ocean[edit]

Advances in trace element testing have allowed scientists to discover traces of dissolved gallium in the Atlantic and Pacific Oceans ^[89] In recent years, dissolved gallium concentrations have presented in the Beaufort Sea.^[89][90] These reports reflect the possible profiles of the Pacific and Atlantic Ocean waters.^[90] For the Pacific Oceans, typical dissolved gallium concentrations are between 4–6 pmol/kg at depths <~150 m. In comparison, for Atlantic waters 25–28 pmol/kg at depths >~350 m.^[90]

Gallium has entered our oceans mainly through Aeolian input, but having gallium in our oceans can be used to resolve aluminum distribution in the oceans.^[91] The reason for this is that gallium is geochemically similar to aluminum, just less reactive. Gallium also has a slightly larger surface water residence time than aluminum.^[91] Gallium has a similar dissolved profile similar to that of aluminum, due to this gallium can be used as a tracer for aluminum.^[91] Gallium can also be used as a tracer of aeolian inputs of iron.^[92] Gallium is used as a tracer for iron in the northwest Pacific, south and central Atlantic Oceans.^[92] For example, in the northwest Pacific, low gallium surface waters, in the subpolar region suggest that there is low dust input, which can subsequently explain the following high-nutrient, low-chlorophyll environmental behavior.^[92]

Precautions[edit]

Metallic gallium is not toxic. However, exposure to gallium halide complexes can result in acute toxicity.^[93] The Ga³⁺ ion of soluble gallium salts tends to form the insoluble hydroxide when injected in large doses; precipitation of this hydroxide resulted in nephrotoxicity in animals. In lower doses, soluble gallium is tolerated well and does not accumulate as a poison, instead being excreted mostly through urine. Excretion of gallium occurs in two phases: the first phase has a biological half-life of 1 hour, while the second has a biological half-life of 25 hours.^[80]

References[edit]

1. ^'Standard Atomic Weights: Gallium'. CIAAW. 1987.
2. ^ ^abZhang Y; Evans JRG; Zhang S (2011). 'Corrected Values for Boiling Points and Enthalpies of Vaporization of Elements in Handbooks'. J. Chem. Eng. Data. 56 (2): 328–337. doi:10.1021/je1011086.
3. ^Ga(−3) has been observed in LaGa, see Dürr, Ines; Bauer, Britta; Röhr, Caroline (2011). 'Lanthan-Triel/Tetrel-ide La(Al,Ga)_x(Si,Ge)_1-x. Experimentelle und theoretische Studien zur Stabilität intermetallischer 1:1-Phasen'(PDF). Z. Naturforsch. (in German). 66b: 1107–1121.
4. ^Hofmann, Patrick (1997). Colture. Ein Programm zur interaktiven Visualisierung von Festkörperstrukturen sowie Synthese, Struktur und Eigenschaften von binären und ternären Alkali- und Erdalkalimetallgalliden(PDF) (Thesis) (in German). PhD Thesis, ETH Zurich. p. 72. doi:10.3929/ethz-a-001859893. hdl:20.500.11850/143357. ISBN978-3728125972.
5. ^Weast, Robert (1984). CRC, Handbook of Chemistry and Physics. Boca Raton, Florida: Chemical Rubber Company Publishing. pp. E110. ISBN0-8493-0464-4.
6. ^Scerri, Eric (2020). The Periodic Table: Its Story and Its Significance. Oxford University Press. p. 149. ISBN978-0-19-091436-3.
7. ^Cobelo-García, A.; Filella, M.; Croot, P.; Frazzoli, C.; Du Laing, G.; Ospina-Alvarez, N.; Rauch, S.; Salaun, P.; Schäfer, J.; Zimmermann, S. (2015). 'COST action TD1407: network on technology-critical elements (NOTICE)—from environmental processes to human health threats'. Environmental Science and Pollution Research International. 22 (19): 15188–15194. doi:10.1007/s11356-015-5221-0. ISSN0944-1344. PMC4592495. PMID26286804.
8. ^Romero-Freire, Ana; Santos-Echeandía, Juan; Neira, Patricia; Cobelo-García, Antonio (2019). 'Less-Studied Technology-Critical Elements (Nb, Ta, Ga, In, Ge, Te) in the Marine Environment: Review on Their Concentrations in Water and Organisms'. Frontiers in Marine Science. 6. doi:10.3389/fmars.2019.00532. ISSN2296-7745.
9. ^ ^abGreenwood and Earnshaw, p. 222
10. ^Tsai, W. L; Hwu, Y.; Chen, C. H.; Chang, L. W.; Je, J. H.; Lin, H. M.; Margaritondo, G. (2003). 'Grain boundary imaging, gallium diffusion and the fracture behavior of Al–Zn Alloy – An in situ study'. Nuclear Instruments and Methods in Physics Research Section B. 199: 457–463. Bibcode:2003NIMPB.199..457T. doi:10.1016/S0168-583X(02)01533-1.
11. ^Vigilante, G. N.; Trolano, E.; Mossey, C. (June 1999). 'Liquid Metal Embrittlement of ASTM A723 Gun Steel by Indium and Gallium'. Defense Technical Information Center. Retrieved 2009-07-07.
12. ^Sublette, Cary (2001-09-09). 'Section 6.2.2.1'. Nuclear Weapons FAQ. Retrieved 2008-01-24.
13. ^Preston–Thomas, H. (1990). 'The International Temperature Scale of 1990 (ITS-90)'(PDF). Metrologia. 27 (1): 3–10. Bibcode:1990Metro..27....3P. doi:10.1088/0026-1394/27/1/002.
14. ^'ITS-90 documents at Bureau International de Poids et Mesures'.
15. ^Magnum, B. W.; Furukawa, G. T. (August 1990). 'Guidelines for Realizing the International Temperature Scale of 1990 (ITS-90)'(PDF). National Institute of Standards and Technology. NIST TN 1265. Archived from the original(PDF) on 2003-07-04.
16. ^Strouse, Gregory F. (1999). 'NIST realization of the gallium triple point'. Proc. TEMPMEKO. 1999 (1): 147–152. Retrieved 2016-10-30.
17. ^Parravicini, G. B.; Stella, A.; Ghigna, P.; Spinolo, G.; Migliori, A.; d'Acapito, F.; Kofman, R. (2006). 'Extreme undercooling (down to 90K) of liquid metal nanoparticles'. Applied Physics Letters. 89 (3): 033123. Bibcode:2006ApPhL..89c3123P. doi:10.1063/1.2221395.
18. ^Greenwood and Earnshaw, p. 224
19. ^ ^abGreenwood and Earnshaw, p. 221
20. ^ ^abRosebury, Fred (1992). Handbook of Electron Tube and Vacuum Techniques. Springer. p. 26. ISBN978-1-56396-121-2.
21. ^Bernascino, M.; et al. (1995). 'Ab initio calculations of structural and electronic properties of gallium solid-state phases'. Phys. Rev. B. 52 (14): 9988–9998. Bibcode:1995PhRvB..52.9988B. doi:10.1103/PhysRevB.52.9988. PMID9980044.
22. ^'Phase Diagrams of the Elements', David A. Young, UCRL-51902 'Prepared for the U.S. Energy Research & Development Administration under contract No. W-7405-Eng-48'. (1975)
23. ^Greenwood and Earnshaw, p. 223
24. ^Yagafarov, O. F.; Katayama, Y.; Brazhkin, V. V.; Lyapin, A. G.; Saitoh, H. (November 7, 2012). 'Energy dispersive x-ray diffraction and reverse Monte Carlo structural study of liquid gallium under pressure'. Physical Review B. 86 (17): 174103. Bibcode:2012PhRvB..86q4103Y. doi:10.1103/PhysRevB.86.174103 – via APS.
25. ^Drewitt, James W. E.; Turci, Francesco; Heinen, Benedict J.; Macleod, Simon G.; Qin, Fei; Kleppe, Annette K.; Lord, Oliver T. (April 9, 2020). 'Structural Ordering in Liquid Gallium under Extreme Conditions'. Physical Review Letters. 124 (14): 145501. Bibcode:2020PhRvL.124n5501D. doi:10.1103/PhysRevLett.124.145501. PMID32338984. S2CID216177238 – via DOI.org (Crossref).
26. ^Audi, Georges; Bersillon, Olivier; Blachot, Jean; Wapstra, Aaldert Hendrik (2003), 'The NUBASE evaluation of nuclear and decay properties', Nuclear Physics A, 729: 3–128, Bibcode:2003NuPhA.729....3A, doi:10.1016/j.nuclphysa.2003.11.001
27. ^Greenwood and Earnshaw, p. 240
28. ^ ^abcdefghWiberg, Egon; Wiberg, Nils; Holleman, Arnold Frederick (2001). Inorganic chemistry. Academic Press. ISBN978-0-12-352651-9.
29. ^ ^abcdefghDowns, Anthony John (1993). Chemistry of aluminium, gallium, indium, and thallium. Springer. ISBN978-0-7514-0103-5.
30. ^ ^abcdEagleson, Mary, ed. (1994). Concise encyclopedia chemistry. Walter de Gruyter. p. 438. ISBN978-3-11-011451-5.
31. ^ ^abSipos, P. L.; Megyes, T. N.; Berkesi, O. (2008). 'The Structure of Gallium in Strongly Alkaline, Highly Concentrated Gallate Solutions—a Raman and ⁷¹
    Ga
    -NMR Spectroscopic Study'. J Solution Chem. 37 (10): 1411–1418. doi:10.1007/s10953-008-9314-y. S2CID95723025.
32. ^Hampson, N. A. (1971). Harold Reginald Thirsk (ed.). Electrochemistry—Volume 3: Specialist periodical report. Great Britain: Royal Society of Chemistry. p. 71. ISBN978-0-85186-027-5.
33. ^ ^abcdefghiGreenwood, N. N. (1962). Harry Julius Emeléus; Alan G. Sharpe (eds.). Advances in inorganic chemistry and radiochemistry. 5. Academic Press. pp. 94–95. ISBN978-0-12-023605-3.
34. ^Madelung, Otfried (2004). Semiconductors: data handbook (3rd ed.). Birkhäuser. pp. 276–277. ISBN978-3-540-40488-0.
35. ^Krausbauer, L.; Nitsche, R.; Wild, P. (1965). 'Mercury gallium sulfide, HgGa
    ₂S
    ₄, a new phosphor'. Physica. 31 (1): 113–121. Bibcode:1965Phy....31..113K. doi:10.1016/0031-8914(65)90110-2.
36. ^Michelle Davidson (2006). Inorganic Chemistry. Lotus Press. p. 90. ISBN978-81-89093-39-6.
37. ^Arora, Amit (2005). Text Book Of Inorganic Chemistry. Discovery Publishing House. pp. 389–399. ISBN978-81-8356-013-9.
38. ^Downs, Anthony J.; Pulham, Colin R. (1994). Sykes, A. G. (ed.). Advances in Inorganic Chemistry. 41. Academic Press. pp. 198–199. ISBN978-0-12-023641-1.
39. ^ ^abcGreenwoood and Earnshaw, pp. 262–5
40. ^Uhl, W. and Halvagar, M. R.; et al. (2009). 'Reducing Ga-H and Ga-C Bonds in Close Proximity to Oxidizing Peroxo Groups: Conflicting Properties in Single Molecules'. Chemistry: A European Journal. 15 (42): 11298–11306. doi:10.1002/chem.200900746. PMID19780106.CS1 maint: multiple names: authors list (link)
41. ^Amemiya, Ryo (2005). 'GaCl₃ in Organic Synthesis'. European Journal of Organic Chemistry. 2005 (24): 5145–5150. doi:10.1002/ejoc.200500512.
42. ^Ball, Philip (2002). The Ingredients: A Guided Tour of the Elements. Oxford University Press. p. 105. ISBN978-0-19-284100-1.
43. ^ ^abcGreenwood and Earnshaw, p. 217.
44. ^Lecoq de Boisbaudran, Paul Émile (1875). 'Caractères chimiques et spectroscopiques d'un nouveau métal, le gallium, découvert dans une blende de la mine de Pierrefitte, vallée d'Argelès (Pyrénées)'. Comptes Rendus Hebdomadaires des Séances de l'Académie des Sciences. 81: 493–495.
45. ^ ^abWeeks, Mary Elvira (1932). 'The discovery of the elements. XIII. Some elements predicted by Mendeleeff'. Journal of Chemical Education. 9 (9): 1605–1619. Bibcode:1932JChEd...9.1605W. doi:10.1021/ed009p1605.
46. ^Petkof, Benjamin (1978). 'Gallium'(PDF). GPO. USGS Minerals Yearbook.
47. ^'An Overview of Gallium'. AZoNetwork. 18 December 2001.
48. ^ ^abcFrenzel, Max (2016). 'The distribution of gallium, germanium and indium in conventional and non-conventional resources – Implications for global availability (PDF Download Available)'. ResearchGate. doi:10.13140/rg.2.2.20956.18564. Retrieved 2017-06-02.
49. ^Burton, J. D.; Culkin, F.; Riley, J. P. (2007). 'The abundances of gallium and germanium in terrestrial materials'. Geochimica et Cosmochimica Acta. 16 (1): 151–180. Bibcode:1959GeCoA..16..151B. doi:10.1016/0016-7037(59)90052-3.
50. ^Frenzel, Max; Hirsch, Tamino; Gutzmer, Jens (July 2016). 'Gallium, germanium, indium, and other trace and minor elements in sphalerite as a function of deposit type — A meta-analysis'. Ore Geology Reviews. 76: 52–78. doi:10.1016/j.oregeorev.2015.12.017.
51. ^ ^abKramer, Deborah A. 'Mineral Commodity Summary 2006: Gallium'(PDF). United States Geological Survey. Retrieved 2008-11-20.
52. ^Kramer, Deborah A. 'Mineral Yearbook 2006: Gallium'(PDF). United States Geological Survey. Retrieved 2008-11-20.
53. ^Xiao-quan, Shan; Wen, Wang & Bei, Wen (1992). 'Determination of gallium in coal and coal fly ash by electrothermal atomic absorption spectrometry using slurry sampling and nickel chemical modification'. Journal of Analytical Atomic Spectrometry. 7 (5): 761. doi:10.1039/JA9920700761.
54. ^'Gallium in West Virginia Coals'. West Virginia Geological and Economic Survey. 2002-03-02.
55. ^Font, O; Querol, Xavier; Juan, Roberto; Casado, Raquel; Ruiz, Carmen R.; López-Soler, Ángel; Coca, Pilar; Peña, Francisco García (2007). 'Recovery of gallium and vanadium from gasification fly ash'. Journal of Hazardous Materials. 139 (3): 413–23. doi:10.1016/j.jhazmat.2006.02.041. PMID16600480.
56. ^Headlee, A. J. W. & Hunter, Richard G. (1953). 'Elements in Coal Ash and Their Industrial Significance'. Industrial and Engineering Chemistry. 45 (3): 548–551. doi:10.1021/ie50519a028.
57. ^ ^abcdFrenzel, Max; Ketris, Marina P.; Seifert, Thomas; Gutzmer, Jens (March 2016). 'On the current and future availability of gallium'. Resources Policy. 47: 38–50. doi:10.1016/j.resourpol.2015.11.005.
58. ^Frenzel, Max; Hirsch, Tamino; Gutzmer, Jens (2016). 'Gallium, germanium, indium, and other trace and minor elements in sphalerite as a function of deposit type — A meta-analysis'. Ore Geology Reviews. 76: 52–78. doi:10.1016/j.oregeorev.2015.12.017. ISSN0169-1368.
59. ^ ^abMoskalyk, R. R. (2003). 'Gallium: the backbone of the electronics industry'. Minerals Engineering. 16 (10): 921–929. doi:10.1016/j.mineng.2003.08.003.
60. ^Frenzel, M; Tolosana-Delgado, R; Gutzmer, J (2015). 'Assessing the supply potential of high-tech metals – A general method'. Resources Policy. 46: 45–58. doi:10.1016/j.resourpol.2015.08.002.
61. ^Frenzel, Max; Mikolajczak, Claire; Reuter, Markus A.; Gutzmer, Jens (June 2017). 'Quantifying the relative availability of high-tech by-product metals – The cases of gallium, germanium and indium'. Resources Policy. 52: 327–335. doi:10.1016/j.resourpol.2017.04.008.
62. ^Gallium – In: USGS Mineral Commodity Summaries(PDF). United States Geological Survey. 2017.
63. ^ ^abcdefGalium. USGS (2018)
64. ^Greber, J. F. (2012) 'Gallium and Gallium Compounds' in Ullmann's Encyclopedia of Industrial Chemistry, Wiley-VCH, Weinheim, doi:10.1002/14356007.a12_163.
65. ^Coleman, James J.; Jagadish, Chennupati; Catrina Bryce, A. (2012-05-02). Advances in Semiconductor Lasers. pp. 150–151. ISBN978-0-12-391066-0.
66. ^Crisp, D.; Pathare, A.; Ewell, R. C. (2004). 'The performance of gallium arsenide/germanium solar cells at the Martian surface'. Acta Astronautica. 54 (2): 83–101. Bibcode:2004AcAau..54...83C. doi:10.1016/S0094-5765(02)00287-4.
67. ^Alberts, V.; Titus J.; Birkmire R. W. (2003). 'Material and device properties of single-phase Cu(In,Ga)(Se,S)₂ alloys prepared by selenization/sulfurization of metallic alloys'. Thin Solid Films. 451–452: 207–211. Bibcode:2004TSF...451..207A. doi:10.1016/j.tsf.2003.10.092.
68. ^Surmann, P; Zeyat, H (Nov 2005). 'Voltammetric analysis using a self-renewable non-mercury electrode'. Analytical and Bioanalytical Chemistry. 383 (6): 1009–13. doi:10.1007/s00216-005-0069-7. ISSN1618-2642. PMID16228199. S2CID22732411.
69. ^Knight, Will (2005-05-05). 'Hot chips chilled with liquid metal'. Archived from the original on 2007-02-11. Retrieved 2008-11-20.
70. ^Martin, Yves. 'High Performance Liquid Metal Thermal Interface for Large Volume Production'(PDF).
71. ^United States. Office of Naval Research. Committee on the Basic Properties of Liquid Metals, U.S. Atomic Energy Commission (1954). Liquid-metals handbook. U.S. Govt. Print. Off. p. 128.
72. ^Besmann, Theodore M. (2005). 'Thermochemical Behavior of Gallium in Weapons-Material-Derived Mixed-Oxide Light Water Reactor (LWR) Fuel'. Journal of the American Ceramic Society. 81 (12): 3071–3076. doi:10.1111/j.1151-2916.1998.tb02740.x.
73. ^Chitambar, Christopher R. (2018). 'Chapter 10. Gallium Complexes as Anticancer drugs'. In Sigel, Astrid; Sigel, Helmut; Freisinger, Eva; Sigel, Roland K. O. (eds.). Metallo-Drugs: Development and Action of Anticancer Agents. Metal Ions in Life Sciences. 18. Berlin: de Gruyter GmbH. pp. 281–301. doi:10.1515/9783110470734-016. ISBN9783110470734. PMID29394029.
74. ^'gallium nitrate'. Archived from the original on 2009-06-08. Retrieved 2009-07-07.
75. ^Bernstein, L. R.; Tanner, T.; Godfrey, C. & Noll, B. (2000). 'Chemistry and Pharmacokinetics of Gallium Maltolate, a Compound With High Oral Gallium Bioavailability'. Metal-Based Drugs. 7 (1): 33–47. doi:10.1155/MBD.2000.33. PMC2365198. PMID18475921.
76. ^'A Trojan-horse strategy selected to fight bacteria'. INFOniac.com. 2007-03-16. Retrieved 2008-11-20.
77. ^Smith, Michael (2007-03-16). 'Gallium May Have Antibiotic-Like Properties'. MedPage Today. Retrieved 2008-11-20.
78. ^Goldberg D. E.; Sharma V.; Oksman A.; Gluzman I. Y.; Wellems T. E.; Piwnica-Worms D. (1997). 'Probing the chloroquine resistance locus of Plasmodium falciparum with a novel class of multidentate metal(III) coordination complexes'. J. Biol. Chem. 272 (10): 6567–72. doi:10.1074/jbc.272.10.6567. PMID9045684. S2CID3408513.
79. ^Biot, Christophe; Dive, Daniel (2010). 'Bioorganometallic Chemistry and Malaria'. Medicinal Organometallic Chemistry. Topics in Organometallic Chemistry. 32. p. 155. doi:10.1007/978-3-642-13185-1_7. ISBN978-3-642-13184-4. S2CID85940061.
80. ^ ^abNordberg, Gunnar F.; Fowler, Bruce A.; Nordberg, Monica (7 August 2014). Handbook on the Toxicology of Metals (4th ed.). Academic Press. pp. 788–90. ISBN978-0-12-397339-9.
81. ^Banerjee, Sangeeta Ray; Pomper, Martin G. (June 2013). 'Clinical Applications of Gallium-68'. Appl. Radiat. Isot. 76: 2–13. doi:10.1016/j.apradiso.2013.01.039. PMC3664132. PMID23522791.
82. ^'Gallium 203319'. Sigma Aldrich.
83. ^'MSDS – 203319'. Sigma Aldrich.
84. ^'Russian American Gallium Experiment'. 2001-10-19. Archived from the original on 2010-07-05. Retrieved 2009-06-24.
85. ^'Neutrino Detectors Experiments: GALLEX'. 1999-06-26. Retrieved 2008-11-20.
86. ^'Nano lab produces world's smallest book'. Simon Fraser University. 11 April 2007. Retrieved 31 January 2013.
87. ^US 5069803, Sugimura, Kentaro; Hasimoto, Shoji & Ono, Takayuki, 'Use of a synthetic resin composition containing gallium particles in the glide surfacing material of skis and other applications', issued 1995
88. ^Kean, Sam (2010). The Disappearing Spoon: And Other True Tales of Madness, Love, and the History of the World from the Periodic Table of the Elements. Boston: Little, Brown and Company. ISBN978-0-316-05164-4.
89. ^ ^abOrians, K. J.; Bruland, K. W. (April 1988). 'Dissolved Gallium in the Open Ocean'. Nature. 332 (21): 717–19. Bibcode:1988Natur.332..717O. doi:10.1038/332717a0. S2CID4323435.
90. ^ ^abcMcAlister, Jason A.; Orians, Kristin J. (20 December 2015). 'Dissolved Gallium in the Beaufort Sea of the Western Arctic Ocean: A GEOTRACES cruise in the International Polar Year'. Marine Chemistry. 177 (Part 1): 101–109. doi:10.1016/j.marchem.2015.05.007. Retrieved 29 August 2021 – via ScienceDirect.
91. ^ ^abcShiller, A. M. (June 1998). 'Dissolved Gallium in the Atlantic Ocean'. Marine Chemistry. 61 (1): 87–99. doi:10.1016/S0304-4203(98)00009-7.
92. ^ ^abcShiller, A. M.; Bairamadgi, G. R. (August 2006). 'Dissolved Gallium in the northwest Pacific and the south and central Atlantic Oceans: Implications for aeolian Fe input and reconsideration of Profiles'. Geochemistry, Geophysics, Geosystems. 7 (8): n/a. Bibcode:2006GGG.....7.8M09S. doi:10.1029/2005GC001118.
93. ^Ivanoff, C. S.; Ivanoff, A. E.; Hottel, T. L. (February 2012). 'Gallium poisoning: a rare case report'. Food Chem. Toxicol. 50 (2): 212–5. doi:10.1016/j.fct.2011.10.041. PMID22024274.

Bibliography[edit]

• Greenwood, Norman N.; Earnshaw, Alan (1997). Chemistry of the Elements (2nd ed.). Butterworth-Heinemann. ISBN978-0-08-037941-8.

External links[edit]

• Gallium at The Periodic Table of Videos (University of Nottingham)
• Safety data sheet at acialloys.com
• [httpd://minerals.usgs.gov/minerals/pubs/commodity/gallium/460798.pdf Price development of gallium 1959–1998]
• Physical and thermodynamical properties of liquid gallium (doc pdf)

Whether you’ve been online dating for what feels like forever or are totally new to the search for love — or a date — online, there’s no denying dating apps are growing in popularity. In these strange, uncertain times, searching for your significant other, online speed dating, or simply connecting with locals you may not have encountered yet through dating apps have become commonplace activities. But with so many dating apps around to choose from, each offering unique and exclusive features, how do you know which one will help you find The One?

We’ve gathered and broken down some of the best iOS apps and Android apps around so you can get back to the dating life, and we’ve answered some of your most commonly asked dating questions. You can also check out the best dating apps for dating during the coronavirus to help you find The One while social distancing, or explore our picks of the best dating apps for women.

Getting started with dating apps

If you’re totally new to the world of online dating, where do you start? That depends on a few factors, like your age and what you’re looking for from online dating.

Searching for a serious relationship? We’d recommend avoiding apps aimed at — or commonly used for — hookups, like Tinder and Pure, and opt for those providing paid membership. Apps like Match, Hinge, and Heybaby tend to attract members looking for something more serious than a hookup — or download a local dating app such as Happn if you’re keen to discover potential dates in your neighborhood. These same unofficial rules apply for older daters too — paid apps tend to appeal to a more mature audience, so avoid gamification and “swipe left/right” apps in favor of those apps that ask you to include a bit more than just a picture on your profile.

Younger daters under the age of 18 will often find most dating apps require you to be over 18 to use them — and although there’s often no age verification process, the requirement is for your own safety, so sticking to it is recommended. Apps like Kippo and XO — where the focus isn’t solely on dating but on sharing interests, activities, and games — would be our recommendations for younger people dating online, but do check the terms and conditions before downloading apps and signing up.

Fairytrail

Fairytrail is a fairly new app aimed at remote workers, digital nomads, and travelers. The app claims 93% of its users are fully mobile or aspire to live this type of lifestyle. So if you’re never in one place for too long or you’d like to travel more, this is a great way to meet a like-minded mate.

You can sign up with email or your Google or Facebook account, after which a cute animated owl asks you some questions about yourself. The profile you’re creating digs a little deeper than with some other dating apps, asking you questions like, “What’s the most adventurous thing you’ve ever done?” and “What values matter most to you?” Then you’re asked to choose a Fairytrail character from a selection of characters, each with their own specified personality type — such as Rapunzel (adventurous) or Pocahontas (open-minded). Upload three profile pictures — one of which must show your face, and another which has to show your full body — and you’re good to go.

You can get started exploring profiles straight away or set your preferences. You can choose what type of character you’d like to meet, like Aladdin (ambitious) or Peter Pan (youthful), or filter matches by age, gender, current country, mobility, religion, ethnicity, and more. In the Explore tab, you can view profiles, tapping Skip to pass over the person or Adore to like them — it’s that simple. It’s worth noting you won’t be able to chat until you pay your one-time entrance fee of $2.99. Profiles here are more in-depth than some other apps, covering things like hobbies, values, top wishes, how mobile somebody is (in terms of traveling or being a digital nomad), as well as their height, religion, and the languages they speak. If you both “Adore” each other, it’s a match! You can then video or text chat through the app for your first date.

If we had any criticisms of Fairytrail, it’s that it isn’t particularly inclusive. You can only choose between two gender options, male or female, when creating your profile, which is sure to turn many users off the app. There have also been some complaints that the small fees you’re charged for various activities can quickly add up — and there isn’t much information about this when you first download the app. Fairytrail also seems to focus quite heavily on looks, with a guide to what’s attractive available on the photos upload page, plus the requirement to upload a full body picture. It’s also not the most colorful app around, and the design is fairly basic, so if this is important to you, you might want to look elsewhere. Finally, it’s worth noting that Fairytrail is fairly new, so it might be harder to find a match if you’re not willing to explore living a fully mobile lifestyle or if you want to match based on a more obscure location.

Heybaby

Heybaby is the dating app for those with kids or those who know they want them someday. If that’s you, you’re in luck. Unlike other apps, where you need to have the awkward, “So do you … um … want kids?” conversation, you already know that if somebody’s on Heybaby, they most definitely want kids, or they already have them. They may even have some and want more. The app is a great place for single parents to connect with others, but it’s also ideal if you’re thinking about starting a family in the near future and don’t want to waste time dating those who aren’t of a similar mindset.

Heybaby was founded by Diko Daghlian, Chas McFeely, and Rene Van De Zande, three dads who decided “the kid conversation” should be front and center when dating. When you sign up, you’ll answer questions about your family and your hopes and dreams for the future — such as if you already have kids and if you want to have more. The app also asks you lifestyle questions about your work, travel preferences, and interests in a bid to connect those with a compatible lifestyle and views on parenting.

With its sleek, modern design and minimalistic interface, Heybaby is a delight to use, but it’s anyone’s guess how the app’s user base will grow. There are plenty of positive reviews so far, with the main complaint among users being that there aren’t enough people on Heybaby to match with just yet — the user base is pretty small as Heybaby has only been around since the summer. The app launched first in San Francisco, so if you live here, you might strike gold — and, generally speaking, those in major cities have more chance of finding a like-minded match than those living in more rural areas. The latest features include the option to record a 10-second video for verification purposes and to introduce yourself to others. You can choose to show this on your profile or keep it hidden. Heybaby is iOS-only for now, but an Android version will hopefully soon be in the works.

Chispa

Chispa is the largest Latino dating app with over four million downloads. Created by Match Group, it’s designed to help Latino single men and Latina single women connect with those who share similar interests. The app operates on a swipe functionality: swipe right if you’re interested — and if the match is mutual, you’ll be able to chat — and swipe left to pass.

There are plenty of options available to customize your search for the perfect partner, whether you’re looking for somebody who’s a specific height or body type or prefer to match on shared interests. It’s free to use the app but you can upgrade to Premium for $10 per month, which gives you unlimited swipes, five “Super Chispas” (like Tinder’s Super Likes) a day, profile boost, and the ability to rewind swipes. There’s also Elite membership, which gives you all the aforementioned features plus the ability to see who’s liked you.

The most recently added feature is a collaboration with Tragos (the Latino party card game) which acts as an ice breaker, using common Latinx themes and universal cultural anecdotes to pose hilarious questions that you can display answers to on your profile. It’s a great opportunity to connect with others on cultural references and upbringing, with questions like “Do you fear la chancla?” or “Ever get hit with ‘¿el novio/la novia?’ at family gatherings?”

It’s worth noting that Chispa isn’t available in the U.K., so if you live there you’ll want to choose another app from our list instead.

Filter Off

If you’re fed up with turning up to in-person dates only to find there’s zero spark, Filter Off is the app you’ve been waiting for. Founded by Zach Schleien, this “anti-catfishing app” has been responsible for no less than four marriages and six engagements during the pandemic, with the New York Times covering one of the weddings.

Essentially a video speed-dating app, Filter Off asks you to sign up using your phone number, so it’s pretty quick and easy to get started. Choose your display name — use your real name or a nickname — add your birthday, tell the app how you identify, and whether you’re interested in men, women, or both, and then add your photos and email address for receiving date invites and you’re good to go! You’ll need to tell the app where in the world you are, then write your intro — this part is important as your profile picture is blurred before your date, so your bio will be the first thing your date sees — and set the age range of the person you’re interested in meeting.

In the Events tab, you’ll find themed events, such as those aimed at divorced singles, ones themed around users of apps (like Clubhouse), and events for creatives or members of specific communities. Sign up for these and you’ll have a better chance of meeting like-minded individuals on your speed dates. You’ll need to fill out the Matchmaker to tell the app more about what yourself and what you’re looking for in your perfect match, such as whether you’re okay meeting somebody with kids, somebody who is divorced, or somebody with political views that differ from your own. Take your time on these questions, as they’re used to choose your dates, which should arrive over the next few days. If this all seems a little confusing, don’t worry — the app has a tutorial section that takes you through how to make Events and Matchmaker work for you. You’ll find this under the Settings tab.

Once your Matchmaker is complete, you’ll receive five or more live video matches every day, and the option to sign up for a 90-second video date with each one, to see if you’re compatible. After your date, you can choose to pass or continue chatting over text or video. There’s a Report feature too, so if anybody bothers you, it’s easy to get help.

If we had one criticism, it’s that there have been some issues where people have flaked on dates — much like in real life — but as you’re presented with multiple speed video dates every day, it’s not quite so much of a big deal compared to being stood up in person.

Lantern

If you’re the kind of person who likes their dating apps a little … different, then check out one of the newest apps to hit the dating scene. Lantern is the first app to take an entertainment approach to online dating, with story-driven narratives that leverage gamification technology. Combining a weighted algorithm, relationship psychology, and a gorgeous design, the app promises a more meaningful online dating experience.

When you first log in, you’re presented with various genres of “adventure” to choose from. The app then dives into the narrative behind each adventure, presented as a series of written questions or choose-your-own-path videos. Questions are thought-provoking, such as “You just won $50 million. The jet is fueled up. Where do you go? After each question is answered, you’re shown other people who answered the same as you. It’s up to you to take it from there and reach out to start a conversation — but the narrative definitely makes breaking the ice that much easier.

Created by co-founders Caroline Gyllensporre and Yehuda Neuman (son of licensed therapist and award-winning New York Times bestselling author M. Gary Neuman), the app’s playful scenarios are a world away from the mundane swiping-based-solely-on-physical-appearance ethos of some apps. It’s free to download, and there are no ads, but you can sign up to Premium for $5 per month to unlock additional narratives and genres and access other premium features.

The user base is still fairly small, and sometimes the matching doesn’t always work — but the developers are responsive to user feedback and the app is regularly updated. Right now it’s available for iOS only.

Curtn

Rather than wasting time scrolling through photos on other dating apps, only to find out your match is awkward in person and doesn’t share your sense of humor, why not check them out on video first? That’s exactly what you can do with Curtn, an iOS-only app — for now — which focuses on video chats. Instead of photos, users upload a brief video clip for their profile — and it can only be recorded at the time, so there’s no risk you’re viewing an outdated video from someone’s camera roll. You’ll get a much clearer sense of somebody’s personality and humor from a video profile, spending less time searching for your perfect match.

Curtn is a lot of fun whether you’re stuck in lockdown or just cozied up at home looking for a date, hookup, or even some new friends to chat to. It’s free to use, and once you match, you can start a video chat or carry on the conversation via text, if you prefer. It’s safe too, as both users need to agree to a video call before it starts — so there’s no risk you’ll be caught sipping coffee in your cat onesie without your knowledge. The app recently increased the number of people you can view a day from 10 to 20, and added the ability to share what city you live in.

The only downside? Curtn is relatively new, so has a small user base and is currently iOS only, although you can sign up on the site to be notified when the Android version launches.

Kippo

If you’re the type of gal or guy who spends your weekends trying to top the Fortnite leaderboards, raiding with your guild in World of Warcraft, or just enjoying a casual game of Overcooked with friends, then this is the dating app for you. Kippo has been around since 2019, co-founded by former Raya executive David Park. It’s designed to help you find your “player 2” — whether that’s just for gaming on an infrequent or regular basis — or to find romance. The app focuses on “self-expression and authentic connection.” The aim is to get to know each other over a game of League of Legendsor Call of Duty: Modern Warfare rather than feeling pressured to dress up and meet for dinner or drinks.

You can meet gamers locally and worldwide, chat about your favorite games, connect, and plan a game or date night. It’s free to use the app, but you can upgrade to Kippo Infinity for $10 per month to enjoy unlimited DMs and utilize seven cards in your profile instead of three. As well as dating, the app has spawned thousands of friendships, with gamers searching for teammates and guild members through the app — so, if you’re a gamer, this is a great app to download even if you’re not searching for your soulmate.

The latest features include a new Compatibility Card that lets you introduce all the basics about yourself, from sexual and romantic orientation and gender identity to whether you have or want kids or pets — and whether you’re looking for a monogamous or non-monogamous relationship. You can now multi-select gender preferences too, for more control over who you want to see.

It’s worth noting that Kippo isn’t available in the U.K., so if you’re reading this and you live there, you’ll need to choose one of our other apps to boost your dating life instead.

Her

Her is the largest and most popular free dating app in the world for LGBTQ women, with 7 million users worldwide. You’ll need to use your Facebook or Instagram account to sign up, after which you can view other verified users both locally and around the world. The app isn’t just about finding a date or your perfect match, though — there are informative articles about LGBTQ issues, queer events local to you, and a community to be part of, so you can make friends with like-minded women who believe in LGBTQ+ equality and empowerment. To match with another user, just like their photos — if the interest is mutual, the app connects you so you can chat.

Her also hosts social meets and parties in 15 cities worldwide (like London, New York, and Los Angeles). Although there might not be much happening right now due to the pandemic, you can find out when the next event is by downloading the app, and you can also get discounts on tickets.

Her is free to use, but there’s a premium subscription available that lets you see who’s online right now, filter searches by sexuality, and more. Premium starts at $15 per month.

Pure

OK, so Pure is designed for hookups rather than serious dating, but don’t judge a book by its cover — or in this case, an app by its intended purpose. Pure is for those who prefer their dating life with no strings attached, so if that’s you — we’re not judging — then it’s well worth checking the app out. Designed with some pretty cool art, there’s a millennial vibe to Pure — and it’s a space for over-18s only, with a strict no nude photos rule.

When signing up, the app asks for your phone number to prove you’re a real person and uses your location to find potential matches — or you can sign up with your Apple ID on the iOS app. Make sure you outline what you’re looking for when creating your bio — as well as mentioning any boundaries. The aim here is anonymous, spur-of-the-moment connections, so your bio, selfies, matches, conversations, and likes automatically self-destruct every 24 hours — and they’re only visible to others when you’re online. Privacy isn’t a concern, as any photos you send in messages can’t be saved — and if anyone tries to screenshot an image you’ve sent, the app notifies you. Pure recently added an anonymous video chat feature where you can wear a virtual mask to hide your identity.

The user base right now is admittedly a little sparse, so unless you live in a major city, you might strike out with Pure. On the plus side, a smaller user base means fewer bots and people trying to scam you — so Pure remains a fairly safe app to use. On the downside, retyping your bio and uploading your photos every 24 hours can get old pretty fast, but it’s great if you prefer your apps with no strings attached. You can communicate with anybody who messages you for free, but to see other profiles you’ll need to upgrade to Pro for $15 per week or $30 a month.

Pure’s newest features include video chat, where you can enjoy a totally anonymous video chat and opt to “wear” a virtual mask to hide your identity, giving you the opportunity to get to know your match a little better before deciding to meet up in person.

NUiT

Our next app is a little bit different from the others on this list — it’s strictly for those who are into astrology. Not the “Today you will win the lottery” horoscopes that you find in every magazine and newspaper on the planet, but actual, real astrology. We’re talking about the time of your birth, which, along with your sun sign, can be used to create your birth chart — but who has time to create a birth chart to work out your supposed compatibility with your potential match? NUiT takes care of all that, asking you to sign up with your date of birth, then creating your own unique birth chart, which will not only give you insights into your own personality but can also help you see how you connect or clash with others. There are daily horoscopes too, if you’re into that.

NUiT is actually a lot of fun, and it’s a gorgeously designed app that’s free to use. OK, so it can’t tell you if that Cancerian born at 4:45 p.m. on July 5 is going to be your soulmate, but it can give you insight into behaviors, letting you use that insight to understand why people act and think the way they do. NUiT is geared toward inclusivity of the LGBTQ+ community, and includes non-binary gender identity, as well as an expanded spectrum of orientation preferences — so if you’re looking to date somebody of the same sex, your profile won’t be shown to straight users, unlike most heteronormative dating apps.

NUiT’s user base is fairly small, but hopefully, this will grow in the future, and the feedback from users has been mostly positive, with many commenting that they use the app to make friends as well as find potential matches.

OkCupid

OkCupid was once one of the biggest names in the dating biz — and the desktop version has been around for what feels like forever (long before apps were even a thing). These days the reviews for the app are fairly mixed, but it’s still a popular choice if you’re getting back in the dating game. After creating a username, you’ll start your OkCupid journey by filling out a very long profile, which you can link to your Instagram account. You can answer questions, giving both your answer and what you’d like your potential match’s answer to be — creating a percentile score that reflects compatibility between users. The survey has been recently changed to include questions about contentious issues like climate change, so you can filter out people with diametrically opposed views to yourself. You can also choose to make your answers public and note how important they are to you, so prospective matches can see for themselves how compatible you’re likely to be.

All options, including those for accessing the settings and viewing profiles, are located in a slide-out menu. Tap the “matches” option to browse, which, oddly, does not show you the people you’ve matched with but rather, the people you could potentially match with. If that interface is too chaotic for you, tap the “quickmatch” option, which restricts the results to photos only. You can like people or message them in a similar fashion to Tinder, but messaging is your better bet: Users can see who has liked them only if they have upgraded to OKCupid Basic, which costs $10 a month or $30 for six months, and also gives you unlimited likes, removes ads, and unlocks all intros at once.

It’s not perfect. OkCupid has as many downsides as Tinder, and fewer positive ones, with the exception of learning a lot more about your potential dating partners — which can get interesting at times. The interface is extremely clunky and the photos are a little small. You also have to tap on a user’s small image to see a larger version and the person’s profile, which is simply too large for an app. It works on a website, but it’s overkill on an app, and the amount of scrolling required makes it annoying to access. When you exit back to the list, there’s no guarantee that it’ll be in the same order or that it will return you to the spot you scrolled down to, making it extremely hard to keep track of what you’ve already viewed.

Worst of all — anyone can message you. Anyone. And they can message anything to you. If you don’t reply, they’ll probably just keep on messaging you too. Facebook verification helps block a percentage of bots and catfishers from creating accounts, and without it, OkCupid loses a level of reliability. It’s worth noting that if you’re having issues with unwanted messages, you can subscribe to Incognito Mode, which hides your profile from anyone on the site you’ve not already messaged or liked — it also removes ads, and you can turn it on and off at any time.

Tinder

Some other websites may be older, but Tinder is undoubtedly the most famous dating app out there. As such, it’s an obvious choice for our list of the best dating apps. As successful as it is at forming long-distance relationships and successful marriages, Tinder has long been accused of changing dating into some form of hookup game. But it’s the king of the dating hill for a reason and the first port of call for many daters.

Thankfully, the Tinder app no longer requires you to have a Facebook account, but you do have to be older than 18 to sign up. You’ll set up a concise profile that consists of a 500-character bio and up to six images (we suggest always including a photo of yourself doing something fun with friends, or your best selfie). You can also link Tinder to your Instagram account and include info about your employer and/or school. Discovery settings allow you to set preferences for who can find your profile, from distance and proximity to age range. But once that’s over, the real fun begins.

Tinder’s interface is svelte and shows you only a photo, name, and age of each prospect. You can tap on the photo to see additional information about the person, as well as Facebook friends you share (if you’re logged in through your Facebook account). You can then swipe right (to like them), left (to pass), or up if you want to use one of your precious “super likes” to show them you really, really like them. If you and another person have both swiped right on one another, a screen will appear showing you’ve matched and inviting you to send them a message. There’s also a recently added video chat option that lets you check out your match before meeting in person. Free membership comes with limited swipes, and you’ll have to sign up for Tinder Plus, Gold, or Platinum to get features like unlimited swipes.

The photos are large, the app is — comparatively speaking — elegant, and setting up your profile is pretty painless. All things considered, Tinder gets an A for its usability. Also, no one can message you unless you have also expressed an interest in them, which means you get no unsolicited messages. While there are a fair few people on Tinder who use it strictly to collect swipes, many people are actually inclined to meet up in real life, which is not always the case with dating apps. Since Tinder is also one of the most popular dating apps, you’re more likely to come across someone you like who lives nearby. Dating is a numbers game, and Tinder has numbers on its side — even if the app itself is widely regarded as one of the buggiest around.

XO

XO is a solid dating app, but with one big difference: Instead of the usual corny pickup lines and awkward first chats, you and your match play a fun game together, which allows you to get to know each other in a much more natural way. There are a number of icebreakers available, including drawing and word games, so you should be able to find something worth playing with every one of your matches. Playing a game helps to make conversing much more natural, and it gives you an easy conversation starter — even if it’s only about which games you prefer. You can also share funny results on social media, which helps to immediately introduce your new amour into your social circles.

Matching works similarly to other dating apps. You can match with individuals from your Match screen and tap the checkmark for anyone you’re interested in meeting. Or, if you’re the more adventurous type, you can tap the Blind Date option to be matched with someone completely different. You’ll play a game with your blind date and only have your identities revealed at the end of that first game. While you may find that a little scary, the chance to reach outside of your usual physical type may reap dividends, as you could end up connecting with someone you might usually not have.

The free version gets you a limited version of the app, so you’ll need to subscribe for additional features like unlimited likes, seeing who’s liked you, changing any mistaken selections you’ve made, and stripping out ads. A monthly subscription is expensive at $15, but you can buy six months for $60 or a year for $95 to save a little extra cash — though, as always with dating apps, paying upfront can be a little risky, as you’re essentially paying with the hope of not needing it eventually.

Recently added features include the option to invite people to play games by username, so you can play with your friends or a crush; Group Date, which lets you play a four-person game; the Love Letters game; Astrology Match, which matches you with other users based on your star sign — if you’re into that kind of thing; and Mystic Mondays. Also new to the app is Third Wheel, which is pretty much what it sounds like — you’ll be matched with someone, but a member of the XO team will also be in the chat as the third wheel on your date! They’ll perk up your conversation if it gets stale, help out with topics, and play group games with you to help you get to know each other. If you’ve joined the app with a friend who’s also single, check out the new Double Date feature which lets you hunt for matches together. The Role Play feature is also a fun way to see how you and your match navigate different scenarios.

On the downside, the app is still quite new, which means its audience is going to be quite a bit smaller than other dating apps. If you live in a less populated area, this might mean you’re much less likely to find someone within close proximity to yourself. However, it’s definitely one to keep an eye on, as the icebreaking games are definitely a new and fun way to meet people.

Facebook Dating

Why add information to a completely new app when you could just use an app you probably use every single day? Facebook Dating is now available in the U.S. and Europe, and it can leverage everything Facebook already knows about you to help you find a partner.

You don’t have to download a separate app to get started with Facebook Dating, as it’s built into the main Facebook app. To try it out, tap on the menu icon on the upper-right side of your Facebook app. From there, just tap the Dating option — though you may need to tap See More to find it. Tap on Get Started, and you’ll be taken through several steps to set up your profile, including the gender you’re looking for, a confirmation of your location, and a choice of profile picture for your dating profile.

The big advantage of using Facebook as your dating platform is that it already knows an awful lot about you, and while that’s a bit creepy, that data is used to refine your dating choices, making it a boon in this particular case. Facebook can also skim your regular profile for details that it thinks might appeal to potential suitors — though you can remove anything you’re not happy with sharing.

The big worry is that Facebook will accidentally suggest your friends or show that you’re open to dating on your regular profile. Thankfully, this isn’t the case, and Facebook keeps such details quiet. It might take a few days for your first match to arrive, but you’ll get a push notification when it does. If you find someone you like, you just have to tap the Heart icon on your profile to unlock the option to message them.

But there’s another feature that allows you to reach out to that friend or follower you’ve been secretly crushing on for so long — if they return your feelings, that is. Called Secret Crush, this feature allows you to choose up to nine of your Facebook friends or Instagram followers as a secret crush on Facebook Dating. If they have a Dating profile and also select you as one of their crushes, well, Facebook Dating will let you both know your feelings are returned. If your feelings aren’t returned, no one will ever know, making it a no-lose situation. The Stories feature, which works in the same way as Stories on Facebook, lets you share moments from your life to connect with those who are into the same things as you.

Following delays due to privacy concerns, Facebook Dating finally launched in the U.K. and Europe in October and is also available in the U.S. and a variety of South American countries. If you’re in the U.S. and are finding you can’t sign up for Facebook Dating, just check back at a later date and try one of the other apps on this list in the meantime.

Grindr

If you’re gay, bi, trans, or queer, then there’s no better place to find love than Grindr. It’s the largest LGBTQ dating app and dating site out there, and it’s a must-download if you’re looking for that special someone — or just a little fun. Signing up is easy — you can either choose to enter your details the old-fashioned way by filling in the form, or you can quickly sign up with your Facebook account. Once you’re signed up, you’ll want to set a profile picture and a display name, and make it clear whether you’re looking for love, a hookup, or just friends.

With that out of the way, you’ll be able to start seeing who’s in your area. You can favorite people if you want to speak to them later or just really like them, and you can even browse other locations — perfect if you’re heading somewhere else for the weekend or want to make some new friends before a big move. It’s easy to message people — just tap the Messaging icon on their profile — and there are large, high-quality pictures available for each of your matches, so you have a good idea of who you’re meeting up with. You can even location-share for really easy meetups. If something goes wrong, it’s also easy to report or block accounts — though there are a limited number of blocks for free users, which is odd and a serious turnoff.

Using the service is free, but there are limits. Free users only get to see 100 profiles in their area and are limited in other parts of the app, too. If you want to lift those limits, then there are two subscriptions you can take out. The first, Grindr XTRA, allows you to see up to 600 profiles in your area, view people who are online now, remove ads, and add other upgrades for $20 a month. But if you want the best possible experience, then there’s Grindr Unlimited, which has no limit on the number of people you can see, lets you see who’s viewed your profile, and allows for browsing in Incognito mode, as well as allowing you to undo sent messages and photos. Unlimited’s newest features include expiring photo mode, where your sent images expire after one 10-second view, and chat translate, allowing you to communicate with other users who don’t speak your language. Unlimited will set you back $25 a month, though, so it’s quite the investment.

Ship

The first dating app you can download (guilt-free) if you’re not single, Ship has a unique concept. Rather than just being a one-on-one affair, this dating app allows your friends to get in on the dating process by vetting potential matches and sending them over to you — with a few thoughts of their own, most likely. Otherwise, you can use it as a regular dating app, with the option of inviting friends later to get their thoughts before you commit to a date.

Getting started is easy. If you’re looking for love, you download the app, set up your account, and then invite people to join your Crew. Once set up, you can send profiles to your Crew, who’ll then be able to check them out for you and let you know if they think you’ll be a match. If you’re more the matchmaking type, you can individually search on your friend’s behalf and send them any potential suitors, along with your thoughts. A recent update has increased the number of Crews you can have, so you can have separate Crews for different groups of friends.

Once a match has been found, you can chat with them through the app. If you’re a more private individual, you probably don’t see the attraction here. But if you’ve ever sent over screenshots of a potential match to your friends for approval and discussion, then this app is an absolute must-download.

Tastebuds

If music is the food of love, then it’s likely to break your heart if a potential life partner can’t stand your favorite tunes. Tastebuds’ dating app gives you a chance to avoid that, with dating and social pairing matched primarily on musical love. Simply sign up, add the music you like, and get matched up with nearby people who share a similar taste in tunes. If your taste is constantly evolving, you can add your Spotify profile, too, so your profile is kept impeccably up to date. There’s a website version, too.

It’s on the smaller side where these sorts of apps are concerned, with only 500,000 people registered worldwide at the last count. Being iOS-only is only going to restrict that even more — though surveys say Android and iOS owners don’t want to date each other anyway. So, if you’re a bit farther out from an urban area than your average person, well, you may not find many people near you. If you are lucky enough to be close to some Tastebuds members, though, then it’s also worth keeping in mind it’s not just for dating — it’s also useful for finding new friends with similar musical tastes, concert buddies, and even collaborators and new band members.

Coffee Meets Bagel

Coffee Meets Bagel used to require Facebook to create an account, but that’s thankfully no longer the case. Instead, you’ll need to use your phone number to verify yourself, making signing up even easier — and slightly less intrusive.

Once you’ve set up your profile and input your dating preferences, Coffee Meets Bagel will send you a few “bagels” a day — otherwise known as a potential match’s profile. You then have 24 hours to decide whether you want to “like” or “pass” on your bagel. If you like your bagel and they have also liked you, you’ll connect and be able to message one another in a private chat. That chat room expires after eight days, regardless of whether you’ve talked with your bagel or not, and that expiration date imbues an immediacy not found in most other dating apps. You can also earn “beans” that allow for extra app functions, either by purchasing them outright, recommending the app to your friends, or logging in on consecutive days.

The service also offers more specific preference options, so you can narrow choices to certain religious beliefs or ethnicities if those are particularly important to you. You can load up to nine photos and create a much more prolific profile than some other apps. And if you’ve entered any icebreakers into your profile, the app will send one of them to a bagel you’ve connected with as the first message, allowing for a convenient, immediate connection. The fact that chat rooms expire after a week puts some pressure on you to exchange phone numbers or meet up in real life, or you can just quietly fade away without any fuss. The interface is also relatively user-friendly, with large photos and clean text.

Appearances can be deceiving, though. Although Coffee Meets Bagel allows for a range of super-specific preferences, the bagel it sends you may or may not match your specified preferences, and, more often than not, if they do, they will be a significant distance away. The app can also be glitchy, often resulting in slow update and load times, and sometimes it’s frustrating that it sends you only a single bagel a day. You can speed things up a bit by using the Give & Take option, but it’ll cost you a hefty 385 beans to like someone who catches your eye. When you consider a bag of 200 beans will set you back $3, it can quickly become expensive if you’re the impatient type.

You can also subscribe to Premium from $35 per month, $75 for three months, $120 for six months, or $180 for 12 months. This gives you access to read receipts, so you won’t waste time wondering whether your potential match has read your messages, as well as activity reports, which show you how your potential match interacts with the app — and whether they’re likely to make the first move.

Despite the expiration of bagels, the slow pace and infrequency of connecting with potential matches make it all too easy to be super-passive with the app, which can render it useless. However, if you prefer a slower pace, then Coffee Meets Bagel is appealing.

Hinge

Load up Hinge, and you might think you’ve accidentally booted into Tinder. Yes, Hinge looks a lot like Tinder’s younger sister, and given the dating context, that might make you a little uncomfortable. But dive a little deeper, and you’ll uncover more differences. Function-wise, it’s very different and uses common interests to pair with prospective matches. It does this by having you answer a bunch of questions through a Tinder-like interface. Have you been to Berlin? Swipe right. Don’t play croquet? Swipe left. This makes answering questions far easier and less time-consuming, not to mention more fun. The questions themselves aren’t as asinine as those in some other dating apps, and they give you a better sense of someone than 500 characters of description can.

People can message you only if you’ve matched, so there are no unsolicited greetings. You can immediately see what sort of relationship people are looking for, and while that doesn’t sound revolutionary, it reflects the fact that Hinge carries more of a dating expectation than a hookup expectation à la Tinder. Best of all, since the matches are curated by your answers to questions, it’s quite a bit harder to come across someone who’s just looking to send inappropriate pictures — and that’s a big plus in our book.

You can add photos of yourself from Facebook, Instagram, or your camera roll — and link your Instagram, if you like. Hinge used to be based around a Facebook friends-of-friends model, but it has since distanced itself from Facebook, which means it’s a lot harder to run out of potential matches. However, this means Hinge is a lot less unique than it used to be. Like other apps, there’s a free version and a subscription-based version called Preferred. The free membership has limited filters and likes and a reduced ability to see everyone who likes you. The paid membership lifts those restrictions and costs $10 a month, with a reduced fee per month if you sign on for three or six months.

Hinge recently conducted a survey which revealed 65% of users who have been on a video date plan to continue using virtual dates post-pandemic — after all, it’s an easy, no-pressure way to gauge whether you click before meeting in person. Recently added features video chat, which lets you hop on a video call with users you’ve already exchanged messages with, and the new Video Prompts feature, which you can open from the corner of your screen during a video call. Video Prompts is designed to help you kickstart a conversation and share your interests and personality. You can select from one of eight unique conversation themes and you’ll be presented with five Prompts to ask each other, from “getting to know you” questions to interactive Prompts that take you on mini scavenger hunts around your home.

Match

There was no way we could discuss the best dating apps without mentioning the granddaddy of them all. Match was at the top of the dating game long before dating apps like Tinder existed, and its experience shows. Signup is simple but can take a little time — it involves entering your details, answering a few questions about your preferences, and adding a couple of photos. Facebook registration isn’t needed, thankfully.

Match’s version of flirting is sending someone a “wink,” and you can search through the Match database to find winkable people. The service will also provide you with daily personalized matches, which take your interests into consideration. There’s also a personalized dating coach that sends recommendations of people who match your desires — one of the most popular features mentioned in user reviews. The Match interface is also pretty sleek and minimalist, but it’s not as easy to use as, say, Tinder. It uses a set of tabs that run along the top of the display (Matches, Search, Viewed Me, and Mixer), which break up the service’s various functions. It’s not an overly complicated app, but it does take a few minutes to get used to.

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However, to make the most of Match, you’re going to need a subscription, which can get a little pricey — the cheapest option currently available will run you $23 a month for 12 months. If you don’t want to sign up for a year, it’ll cost $42 a month for three months or $26 a month for six months. Is it worth it? Probably — a premium subscription does allow you to see who’s recently looked at your profile and who has liked your pictures, and it includes a host of other features.

The app’s latest updates include the option to start free conversations with your Top Picks.

Bumble

Bumble looks eerily similar to Tinder but functions a tad differently. The big catch with Bumble is that when opposite genders match, the woman must message the guy first — and she only has 24 hours to do so. Guys don’t have as much power, but they can extend matches for 24 hours if they’re really hoping to hear from a particular woman. Ladies can do the same thing if they want to chat with a match but haven’t had time during the first day. For same-gender matches, either person can initiate the conversation first.

It’s a system that promotes an active approach, but not enough to be punishing. The 24-hour time limit to connect with someone adds just enough pressure to start a conversation, so matches don’t languish and get reshuffled into the deck. And if you accidentally nixed someone, just shake your phone to undo your rogue swipe. Profiles are concise, and settings are pared down, like with Tinder, and swiping up allows you to scroll through additional photos.

Bumble also checks the boxes for usability, a slick user interface, and easy profile setup. Also, the relatively ballsy move of designing a dating app where women take the driving seat definitely pays off. It’s the only app that states plainly and prominently that it prohibits pornographic material, requires its users to respect one another, and has a code of conduct in place specifically to make it a safe and friendly place.

If you’re a woman and you hate being the first person to initiate a conversation, then Bumble definitely isn’t for you. Profiles are also very short, consisting of a concise blurb and six photos max. This can make it hard to gauge whether or not you’re interested in someone, even at the most superficial level. Furthermore, because Bumble places the onus on the woman to initiate the conversation, we’ve found that it can attract a more passive crowd than other dating apps. However, if you’re a woman who knows what she wants and isn’t afraid to get it, Bumble is worth a shot.

Bumble recently added in-app voice and video chat functions, as well as the option to send audio notes if you don’t fancy chatting in real time.

Happn

How often do you cross paths with the love of your life before you actually meet them? Maybe you smile at your crush every day when you get your morning coffee, but you’ve never built up the courage to talk. If so, Happn could be for you. It’s a dating app that shows the profiles of other singles and pinpoints the last place and time you were near each other. All your prospective matches are people you’ve crossed paths with, so you’re always starting out with something in common.

You can like people secretly, and they won’t find out unless they like you, too. If you’re comfortable being bolder, you can tap the Charm button to let them know you’re interested. However, Charms cost coins, which you’ll have to buy with real cash via in-app purchases. When you get a match — which Happn calls a Crush — you can start chatting with each other.

It’s very quick and easy to set up and use. The profile creation is pretty standard. You add photos, age, profession, and interests, and you can also specify what you like doing, whether that’s taking a walk in the park, seeing a movie, or going for a drink. Happn also has some nifty integrations — you can use Facebook to set up your profile, hook up your Instagram account to automatically add photos, and add Spotify to see if your musical tastes align with matches.

Happn uses the GPS functionality on your phone to track your movements. If you’ve been within 800 feet of a potential match, then you’ll see their profile. For that reason, it works best for city dwellers. People can’t contact you unless you tap the Heart on their profile. Happn never displays your position to other users in real time, and you can also block users if you have stalking concerns.

Recently added features include video calling — just go to the conversation tab and tap the Video Camera icon to start a call.

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Plenty of Fish

Plenty of Fish is one of the oldest dating services out there, and it’s certainly the biggest after hitting 90 million users in May 2017. With that many users, you’re more likely to find matches quicker. Plenty of Fish itself likes to point that out, saying that users are 2.7 times more likely to be matched in their first 24 hours.

That sort of massive following is a selling point in itself, but Plenty of Fish has more going for it than just pure size. It takes things that work for other apps and includes them in its own, adding Tinder’s swiping mechanics and a Happn-style ability to see matches near to you. It does have its own little twists on the formula — the Spark system allows users to quote any part of their match’s profile, so icebreakers are much easier when you can see what a message is referencing.

Much like other dating apps, Plenty of Fish has you take a chemistry test of your likes and dislikes, and it quizzes you about your wants and needs from a relationship, so you can be sure that you’re likely to be matched with people who are looking for similar outcomes to your own. The best part? It’s completely free and doesn’t charge to message or browse your matches. That makes it the ideal app to download if you’re on the market but aren’t actively searching for love. And if you’re going out of your way to find someone, Plenty of Fish may have your perfect catch. However, the signup process is pretty lengthy, and the layout is rather fiddly on mobile.

You can subscribe to access the app’s premium features, which will set you back $39 for three months, $60 for six months, or $90 for a 12-month subscription.

Recent updates include the LIVE! feature where you can livestream to an audience or host one-on-one video chats, as well as NextDate, a virtual speed dating feature that lets you participate in a series of 90-second video chats from the comfort of home.

Do dating apps really work?

When it comes to whether or not dating apps actually work, the jury’s still out. There are stories of people meeting their future husbands and wives on dating apps, and at the other extreme, horror stories of online dates gone wrong — but neither necessarily represents the average person’s experience of dating apps. The majority of daters in the U.S. report a positive experience with dating apps, but it’s true that to some extent your level of success hinges on choosing the right app for what you’re looking for — and you get out what you put in. Spend time perfecting your dating profile, and, crucially, being honest about yourself and what you’re looking for, and you’re likely to see results. Whether you’ll meet The One on a dating app, we really can’t say, but you will meet people you may never have encountered in everyday life — and it’s worth a shot, right?

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