Gallium

Gallium, ₃₁Ga
Gallium
Pronunciation	/ˈɡæliəm/ (GAL-ee-əm)
Appearance	silvery blue
Standard atomic weight Ar°(Ga)
	69.723±0.001; 69.723±0.001 (abridged);
Gallium in the periodic table
	zinc ← gallium → germanium
Atomic number (Z)	31
Group	group 13 (boron group)
Period	period 4
Block	p-block
Electron configuration	[Ar] 3d10 4s2 4p1
Electrons per shell	2, 8, 18, 3
Physical properties
Phase at STP	solid
Melting point	302.9146 K (29.7646 °C, 85.5763 °F)
Boiling point	2676 K (2403 °C, 4357 °F)
Density (at 20° C)	5.907 g/cm3
when liquid (at m.p.)	6.095 g/cm3
Heat of fusion	5.59 kJ/mol
Heat of vaporization	256 kJ/mol
Molar heat capacity	25.86 J/(mol·K)
Atomic properties
Oxidation states	−5, −4, −3, −2, −1, 0, +1, +2, +3 (an amphoteric oxide)
Electronegativity	Pauling scale: 1.81
Ionization energies	1st: 578.8 kJ/mol ; 2nd: 1979.3 kJ/mol ; 3rd: 2963 kJ/mol ; (more) ;
Atomic radius	empirical: 135 pm
Covalent radius	122±3 pm
Van der Waals radius	187 pm
	Spectral lines of gallium
Other properties
Natural occurrence	primordial
Crystal structure	base-centered orthorhombic (oS8)
Lattice constants	a = 452.05 pm; b = 766.25 pm; c = 452.66 pm (at 20 °C)
Thermal expansion	20.5×10−6/K (at 20 °C)
Thermal conductivity	40.6 W/(m⋅K)
Electrical resistivity	270 nΩ⋅m (at 20 °C)
Magnetic ordering	diamagnetic
Molar magnetic susceptibility	−21.6×10−6 cm3/mol (at 290 K)
Young's modulus	9.8 GPa
Speed of sound thin rod	2740 m/s (at 20 °C)
Poisson ratio	0.47
Mohs hardness	1.5
Brinell hardness	56.8–68.7 MPa
CAS Number	7440-55-3
History
Naming	after Gallia (Latin for: France), homeland of the discoverer
Prediction	Dmitri Mendeleev (1871)
Discovery and first isolation	Lecoq de Boisbaudran (1875)
Isotopes of gallium v; e;
ε	70Zn
	Category: Gallium; view; talk; edit; \| references

Gallium is a chemical element; it has symbol Ga and atomic number 31. Discovered by the French chemist Paul-Émile Lecoq de Boisbaudran in 1875,^[10] 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 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 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.^[11]^[12]

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.

^ "Standard Atomic Weights: Gallium". CIAAW. 1987.
^ 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. (2022-05-04). "Standard atomic weights of the elements 2021 (IUPAC Technical Report)". Pure and Applied Chemistry. doi:10.1515/pac-2019-0603. ISSN 1365-3075.
^ ^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.
^ "Gallium (CAS Number 7440-55-3) : Strem Product Catalog". Strem Chemicals Inc. Retrieved 4 December 2023.
^ ^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.
^ 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.
^ 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.
^ Weast, Robert (1984). CRC, Handbook of Chemistry and Physics. Boca Raton, Florida: Chemical Rubber Company Publishing. pp. E110. ISBN 0-8493-0464-4.
^ 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.
^ Scerri, Eric (2020). The Periodic Table: Its Story and Its Significance. Oxford University Press. p. 149. ISBN 978-0-19-091436-3.
^ 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.
^ 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.

Cite error: There are <ref group=lower-alpha> tags or {{efn}} templates on this page, but the references will not show without a {{reflist|group=lower-alpha}} template or {{notelist}} template (see the help page).

[1] "Standard Atomic Weights: Gallium". CIAAW. 1987.

[CIAAW2021-2] 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. (2022-05-04). "Standard atomic weights of the elements 2021 (IUPAC Technical Report)". Pure and Applied Chemistry. doi:10.1515/pac-2019-0603. ISSN 1365-3075.

[Zhang-3] 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.

[Arblaster_2018-5] 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] 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.

[NUBASE2020-10] 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] 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.

[13] 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.

[1]

[2]

[3]

[4]

[5]

[6]

[7]

[a]

[8]

[9]

[10]

[11]

[12]