Gallium

This article is about the chemical element. For other uses, see Gallium (disambiguation).

Gallium, 31Ga
Gallium
Pronunciation/ˈɡæliəm/ ​(GAL-ee-əm)
Appearancesilvery blue
Standard atomic weight Ar°(Ga)
Gallium in the periodic table
Hydrogen Helium
Lithium Beryllium Boron Carbon Nitrogen Oxygen Fluorine Neon
Sodium Magnesium Aluminium Silicon Phosphorus Sulfur Chlorine Argon
Potassium Calcium Scandium Titanium Vanadium Chromium Manganese Iron Cobalt Nickel Copper Zinc Gallium Germanium Arsenic Selenium Bromine Krypton
Rubidium Strontium Yttrium Zirconium Niobium Molybdenum Technetium Ruthenium Rhodium Palladium Silver Cadmium Indium Tin Antimony Tellurium Iodine Xenon
Caesium Barium Lanthanum Cerium Praseodymium Neodymium Promethium Samarium Europium Gadolinium Terbium Dysprosium Holmium Erbium Thulium Ytterbium Lutetium Hafnium Tantalum Tungsten Rhenium Osmium Iridium Platinum Gold Mercury (element) Thallium Lead Bismuth Polonium Astatine Radon
Francium Radium Actinium Thorium Protactinium Uranium Neptunium Plutonium Americium Curium Berkelium Californium Einsteinium Fermium Mendelevium Nobelium Lawrencium Rutherfordium Dubnium Seaborgium Bohrium Hassium Meitnerium Darmstadtium Roentgenium Copernicium Nihonium Flerovium Moscovium Livermorium Tennessine Oganesson
Al
↑
Ga
↓
In
zinc ← gallium → germanium
Atomic number (Z)31
Groupgroup 13 (boron group)
Periodperiod 4
Block  p-block
Electron configuration[Ar] 3d10 4s2 4p1
Electrons per shell2, 8, 18, 3
Physical properties
Phase at STPsolid
Melting point302.9146 K ​(29.7646 °C, ​85.5763 °F)
Boiling point2676 K ​(2403 °C, ​4357 °F)[3][4]
Density (at 20° C)5.907 g/cm3[5]
when liquid (at m.p.)6.095 g/cm3
Heat of fusion5.59 kJ/mol
Heat of vaporization256 kJ/mol[3]
Molar heat capacity25.86 J/(mol·K)
Vapor pressure
P (Pa) 1 10 100 1 k 10 k 100 k
at T (K) 1310 1448 1620 1838 2125 2518
Atomic properties
Oxidation statescommon: +3
−5,? −4,? −3,[6] −2,? −1,? 0,? +1,[7] +2[7][8]
ElectronegativityPauling scale: 1.81
Ionization energies
  • 1st: 578.8 kJ/mol
  • 2nd: 1979.3 kJ/mol
  • 3rd: 2963 kJ/mol
  • (more)
Atomic radiusempirical: 135 pm
Covalent radius122±3 pm
Van der Waals radius187 pm
Color lines in a spectral range
Spectral lines of gallium
Other properties
Natural occurrenceprimordial
Crystal structure ​base-centered orthorhombic (oS8)
Lattice constants
Base-centered orthorhombic crystal structure for gallium
a = 452.05 pm
b = 766.25 pm
c = 452.66 pm (at 20 °C)[5]
Thermal expansion20.5×10−6/K (at 20 °C)[5][a]
Thermal conductivity40.6 W/(m⋅K)
Electrical resistivity270 nΩ⋅m (at 20 °C)
Magnetic orderingdiamagnetic
Molar magnetic susceptibility−21.6×10−6 cm3/mol (at 290 K)[9]
Young's modulus9.8 GPa
Speed of sound thin rod2740 m/s (at 20 °C)
Poisson ratio0.47
Mohs hardness1.5
Brinell hardness56.8–68.7 MPa
CAS Number7440-55-3
History
Namingafter Gallia (Latin for: France), homeland of the discoverer
PredictionDmitri Mendeleev (1871)
Discovery and first isolationLecoq de Boisbaudran (1875)
Isotopes of gallium
Main isotopes[10] Decay
abun­dance half-life (t1/2) mode pro­duct
66Ga synth 9.5 h β+ 66Zn
67Ga synth 3.3 d ε 67Zn
68Ga synth 1.2 h β+ 68Zn
69Ga 60.1% stable
70Ga synth 21 min β− 70Ge
ε 70Zn
71Ga 39.9% stable
72Ga synth 14.1 h β− 72Ge
73Ga synth 4.9 h β− 73Ge
 Category: Gallium
| references

Gallium is a chemical element; it has the symbol Ga and atomic number 31. Discovered by the French chemist Paul-Émile Lecoq de Boisbaudran in 1875,[11] 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 relatively soft, silvery metal at standard temperature and pressure. In its liquid state, it becomes silvery white. If enough force is applied, solid 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 (29.7646°C, 85.5763°F, 302.9146 K)[12] 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. A 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 rather 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 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.[13][14]

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.

  1. ^ "Standard Atomic Weights: Gallium". CIAAW. 1987.
  2. ^ Prohaska, Thomas; Irrgeher, Johanna; Benefield, Jacqueline; Böhlke, John K.; Chesson, Lesley A.; Coplen, Tyler B.; Ding, Tiping; Dunn, Philip J. H.; Gröning, Manfred; Holden, Norman E.; Meijer, Harro A. J. (4 May 2022). "Standard atomic weights of the elements 2021 (IUPAC Technical Report)". Pure and Applied Chemistry. doi:10.1515/pac-2019-0603. ISSN 1365-3075.
  3. ^ a b Zhang 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.
  4. ^ "Gallium (CAS Number 7440-55-3) : Strem Product Catalog". Strem Chemicals Inc. Retrieved 4 December 2023.
  5. ^ a b c d Arblaster, John W. (2018). Selected Values of the Crystallographic Properties of Elements. Materials Park, Ohio: ASM International. ISBN 978-1-62708-155-9.
  6. ^ 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.
  7. ^ a b Greenwood, Norman N.; Earnshaw, Alan (1997). Chemistry of the Elements (2nd ed.). Butterworth-Heinemann. p. 28. ISBN 978-0-08-037941-8.
  8. ^ 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. ISBN 978-3728125972.
  9. ^ Weast, Robert (1984). CRC, Handbook of Chemistry and Physics. Boca Raton, Florida: Chemical Rubber Company Publishing. pp. E110. ISBN 0-8493-0464-4.
  10. ^ Kondev, F. G.; Wang, M.; Huang, W. J.; Naimi, S.; Audi, G. (2021). "The NUBASE2020 evaluation of nuclear properties" (PDF). Chinese Physics C. 45 (3): 030001. doi:10.1088/1674-1137/abddae.
  11. ^ Scerri, Eric (2020). The Periodic Table: Its Story and Its Significance. Oxford University Press. p. 149. ISBN 978-0-19-091436-3.
  12. ^ "Gallium – Element information, properties and uses | Periodic Table". www.rsc.org.
  13. ^ 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. Bibcode:2015ESPR...2215188C. doi:10.1007/s11356-015-5221-0. ISSN 0944-1344. PMC 4592495. PMID 26286804.
  14. ^ 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. hdl:10261/307794. ISSN 2296-7745.


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