Ga 31

Gallium (Ga)

post-transition-metal

Period: 4 Group: 13 Block: p

Solid

Standard Atomic Weight

Electron configuration

[Ar] 4s² 3d¹⁰ 4p¹

Melting point

29.76 °C (302.91 K)

Boiling point

2203.85 °C (2477 K)

Density

5910 kg/m³

Oxidation states

−5, −4, −3, −2, −1, 0, +1, +2, +3

Electronegativity (Pauling)

1.81

Ionization energy (1st)

Discovery year

1875

Atomic radius

130 pm

Details

Name origin Latin: Gallia (France).

Discovery country France

Discoverers Paul Émile Lecoq de Boisbaudran

Gallium is a soft post-transition metal in group 13, chemically related to aluminium and indium. It is notable for melting just above room temperature, forming low-melting alloys, and supplying semiconductors through compounds such as gallium arsenide and gallium nitride. In nature it is dispersed rather than concentrated in its own ores, so it is recovered mainly as a by-product of aluminium and zinc processing.

It is one of four metals mercury, cesium, and rubidium which can be liquid near room temperature and, thus, can be used in high-temperature thermometers. It has one of the longest liquid ranges of any metal and has a low vapor pressure even at high temperatures.

There is a strong tendency for gallium to supercool below its freezing point. Therefore, seeding may be necessary to initiate solidification.

Ultra-pure gallium has a beautiful, silvery appearance, and the solid metal exhibits a conchoidal fracture similar to glass. The metal expands 3.1 percent on solidifying; therefore, it should not be stored in glass or metal containers, because they may break as the metal solidifies.

High-purity gallium is attacked only slowly by mineral acids.

The name derives from the Latin gallia for France. It was discovered in zinc blende by the French chemist Paul-Emile Lecoq de Boisbaudran in 1875. It was first isolated in 1878 by Lecoq de Boisbaudran and the French chemist Émile-Clément Jungflesch.

First proposed to exist by Dmitri Mendeleyev in 1871 based on gaps in his newly created Periodic Table of Elements, gallium was discovered spectroscopically by the French chemist Paul-Émile Lecoq de Boisbaudran in 1875. Later that same year, Lecoq was able to obtain pure gallium through the electrolysis of a solution of gallium hydroxide (Ga(OH)3) in potassium hydroxide (KOH). Trace amounts of gallium are found in diaspore, sphalerite, germanite and bauxite as well as in the byproducts of burning coal.

From the Latin word Gallia, France; also from Latin, gallus, a translation of "Lecoq," a cock. Predicted and described by Mendeleev as ekaaluminum, and discovered spectroscopically by Lecoq de Boisbaudran in 1875, who in the same year obtained the free metal by electrolysis of a solution of the hydroxide in KOH.

Read about Gallium on Wikipedia

Images

Properties

Physical

Atomic radius (empirical) 130 pm

Covalent radius 122 pm

Van der Waals radius 187 pm

Metallic radius 125 pm

Density

Molar volume 0.0118 L/mol

Phase at STP solid

Melting point 29.76 °C

Boiling point 2203.85 °C

Thermal conductivity 28.1 W/(m·K)

Specific heat capacity 0.373 J/(g·K)

Molar heat capacity 26.03 J/(mol·K)

Crystal structure orthorhombic

Chemical

Electronegativity (Pauling) 1.81

Electronegativity (Allen) 1.756

Electron affinity

Ionization energy (1st)

Ionization energy (2nd)

Ionization energy (3rd)

Ionization energy (4th)

Ionization energy (5th)

Oxidation states −5, −4, −3, −2, −1, 0, +1, +2, +3

Valence electrons 3

Electron configuration

Electron configuration (semantic)

Thermodynamic

Triple point (temperature) 29.7666 °C

Heat of fusion 0.05793647 eV

Heat of vaporization 2.653262 eV

Heat of sublimation 2.808727 eV

Heat of atomization 2.808727 eV

Atomization enthalpy

Nuclear

Stable isotopes 2

Discovery year 1875

Abundance

Abundance (Earth's crust) 19 mg/kg

Abundance (ocean)

Reactivity

N/A

Crystal Structure

Lattice constant a 451 pm

Electronic Structure

Electrons per shell 2, 8, 18, 3

Identifiers

CAS number 7440-55-3

Term symbol

InChI InChI=1S/Ga

InChI Key GYHNNYVSQQEPJS-UHFFFAOYSA-N

Electron Configuration Measured

Ion charge

Protons 31

Electrons 31

Charge Neutral

Configuration Ga: 3d¹⁰ 4s² 4p¹

[Ar] 3d¹⁰ 4s² 4p¹

1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p¹

Orbital diagram

↑↓

2/2

↑↓

2/2

↑↓

6/6

↑↓

2/2

↑↓

6/6

↑↓

2/2

↑↓

10/10

↑

1/6 1↑

Total electrons: 31 Unpaired: 1

Atomic model

Protons 31

Neutrons 38

Electrons 31

Mass number 69

Stability Stable

Isotopes change neutron count, mass, and stability — not the electron configuration of a neutral atom.

Schematic atomic model, not to scale.

Atomic Fingerprint

Emission / Absorption Spectrum

Emission Visible: 380–750 nm

Isotope Distribution

Mass number	Atomic mass (u)	Natural abundance	Half-life
69 Stable	68.9255735 ± 0.0000013	60.1080%	Stable
71 Stable	70.92470258 ± 0.00000087	39.8920%	Stable

Measured

Phase / State

Solid 25 °C (298.15 K)

Reason: 4.8 °C below melting point (29.76 °C)

Melting point 29.76 °C

Boiling point 2203.85 °C

Below melting by 4.8 °C

0 K Current temperature: 25 °C 6000 K

Phase timeline

Schematic, not to scale

Solid

Liquid

Gas

Melting

Boiling

25°C

Solid

Liquid

Gas

Current

Phase transition points

Melting point Literature

29.76 °C

Boiling point Literature

2203.85 °C

Current phase Calculated
Solid

Transition energies

Heat of fusion Literature

0.05793647 eV

Energy required to melt 1 mol at melting point

Heat of vaporization Literature

2.653262 eV

Energy required to vaporize 1 mol at boiling point

Heat of sublimation Literature

2.808727 eV

Energy required to sublime 1 mol at sublimation point

Density

Reference density Literature

5910 kg/m³

At standard conditions

Current density Calculated

5910 kg/m³

At standard conditions

Advanced

Triple point Literature

29.7666 °C

Atomic Spectra

Showing 10 of 31 Atomic Spectra. Sorted by ion charge (ascending).

Lines Holdings ?

Ion	Charge	Total lines	Transition probabilities	Level designations
Ga I	0	342	23	342
Ga II	+1	176	10	176
Ga III	+2	113	2	113
Ga IV	+3	594	0	594
Ga V	+4	185	0	185
Ga VI	+5	501	0	501
Ga VII	+6	451	0	451

NIST Lines Holdings →

Levels Holdings ?

Ion	Charge	Levels
Ga I	0	262
Ga II	+1	96
Ga III	+2	61
Ga IV	+3	192
Ga V	+4	92
Ga VI	+5	158
Ga VII	+6	181
Ga VIII	+7	2
Ga IX	+8	2
Ga X	+9	2

NIST Levels Holdings →

31 Ga 69.723

Gallium — Atomic Orbital Visualizer

[Ar]4s23d104p1

Energy levels 2 8 18 3

Oxidation states -5, -4, -3, -2, -1, 0, +1, +2, +3

HOMO 4p n=4 · l=1 · m=-1

Gallium — Atomic Orbital Visualizer Preview

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31 Ga 69.723

Gallium — Crystal Structure Visualizer

Orthorhombic · Pearson N/A

Experimental

Pearson N/A

Gallium — Crystal Structure Visualizer Preview

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Ionic Radii

Charge	Coordination	Spin	Radius
+3	4	N/A	47 pm
+3	5	N/A	55.00000000000001 pm
+3	6	N/A	62 pm

Compounds

69.723 u

Ga+3

69.723 u

66.928 u

68.926 u

67.928 u

71.926 u

65.932 u

70.925 u

69.926 u

72.925 u

64.933 u

Ga+3

66.928 u

Ga+3

67.928 u

Ga+3

65.932 u

63.937 u

61.944 u

Isotopes (2)

	Mass number	Atomic mass (u)	Natural abundance	Half-life	Decay mode
	69 Stable	68.9255735 ± 0.0000013	60.1080% ± 0.0090%	Stable	stable
	71 Stable	70.92470258 ± 0.00000087	39.8920% ± 0.0090%	Stable	stable

69 Stable

Atomic mass (u) 68.9255735 ± 0.0000013

Natural abundance 60.1080% ± 0.0090%

Half-life Stable

Decay mode

stable

71 Stable

Atomic mass (u) 70.92470258 ± 0.00000087

Natural abundance 39.8920% ± 0.0090%

Half-life Stable

Decay mode

stable

Spectral Lines

Wavelength (nm)	Intensity	Ion stage	Type	Transition	Accuracy	Source
417.33 nm	N/A	ID 486	emission	3s2.3p3 2P* → 3s2.3p3 2P*	Measured	NIST
424.0525 nm	N/A	Ga I	emission	4s2.5s 2S → 4s2.70p 2P*	Measured	NIST
424.0525 nm	N/A	Ga I	emission	4s2.5s 2S → 4s2.70p 2P*	Measured	NIST
424.0651 nm	N/A	Ga I	emission	4s2.5s 2S → 4s2.69p 2P*	Measured	NIST
424.0651 nm	N/A	Ga I	emission	4s2.5s 2S → 4s2.69p 2P*	Measured	NIST
424.08 nm	N/A	Ga I	emission	4s2.5s 2S → 4s2.68p 2P*	Measured	NIST
424.08 nm	N/A	Ga I	emission	4s2.5s 2S → 4s2.68p 2P*	Measured	NIST
424.0924 nm	N/A	Ga I	emission	4s2.5s 2S → 4s2.67p 2P*	Measured	NIST
424.0924 nm	N/A	Ga I	emission	4s2.5s 2S → 4s2.67p 2P*	Measured	NIST
424.1098 nm	N/A	Ga I	emission	4s2.5s 2S → 4s2.66p 2P*	Measured	NIST
424.1098 nm	N/A	Ga I	emission	4s2.5s 2S → 4s2.66p 2P*	Measured	NIST
424.1257 nm	N/A	Ga I	emission	4s2.5s 2S → 4s2.65p 2P*	Measured	NIST
424.1257 nm	N/A	Ga I	emission	4s2.5s 2S → 4s2.65p 2P*	Measured	NIST
424.1406 nm	N/A	Ga I	emission	4s2.5s 2S → 4s2.64p 2P*	Measured	NIST
424.1406 nm	N/A	Ga I	emission	4s2.5s 2S → 4s2.64p 2P*	Measured	NIST
424.1588 nm	N/A	Ga I	emission	4s2.5s 2S → 4s2.63p 2P*	Measured	NIST
424.1588 nm	N/A	Ga I	emission	4s2.5s 2S → 4s2.63p 2P*	Measured	NIST
424.1761 nm	N/A	Ga I	emission	4s2.5s 2S → 4s2.62p 2P*	Measured	NIST
424.1761 nm	N/A	Ga I	emission	4s2.5s 2S → 4s2.62p 2P*	Measured	NIST
424.1948 nm	N/A	Ga I	emission	4s2.5s 2S → 4s2.61p 2P*	Measured	NIST
424.1948 nm	N/A	Ga I	emission	4s2.5s 2S → 4s2.61p 2P*	Measured	NIST
424.2157 nm	N/A	Ga I	emission	4s2.5s 2S → 4s2.60p 2P*	Measured	NIST
424.2157 nm	N/A	Ga I	emission	4s2.5s 2S → 4s2.60p 2P*	Measured	NIST
424.2367 nm	N/A	Ga I	emission	4s2.5s 2S → 4s2.59p 2P*	Measured	NIST
424.2367 nm	N/A	Ga I	emission	4s2.5s 2S → 4s2.59p 2P*	Measured	NIST
424.2582 nm	N/A	Ga I	emission	4s2.5s 2S → 4s2.58p 2P*	Measured	NIST
424.2582 nm	N/A	Ga I	emission	4s2.5s 2S → 4s2.58p 2P*	Measured	NIST
424.2826 nm	N/A	Ga I	emission	4s2.5s 2S → 4s2.57p 2P*	Measured	NIST
424.2826 nm	N/A	Ga I	emission	4s2.5s 2S → 4s2.57p 2P*	Measured	NIST
424.3887 nm	N/A	Ga I	emission	4s2.5s 2S → 4s2.53p 2P*	Measured	NIST
424.3887 nm	N/A	Ga I	emission	4s2.5s 2S → 4s2.53p 2P*	Measured	NIST
424.4204 nm	N/A	Ga I	emission	4s2.5s 2S → 4s2.52p 2P*	Measured	NIST
424.4204 nm	N/A	Ga I	emission	4s2.5s 2S → 4s2.52p 2P*	Measured	NIST
424.4531 nm	N/A	Ga I	emission	4s2.5s 2S → 4s2.51p 2P*	Measured	NIST
424.4531 nm	N/A	Ga I	emission	4s2.5s 2S → 4s2.51p 2P*	Measured	NIST
424.4886 nm	N/A	Ga I	emission	4s2.5s 2S → 4s2.50p 2P*	Measured	NIST
424.4886 nm	N/A	Ga I	emission	4s2.5s 2S → 4s2.50p 2P*	Measured	NIST
424.5261 nm	N/A	Ga I	emission	4s2.5s 2S → 4s2.49p 2P*	Measured	NIST
424.5261 nm	N/A	Ga I	emission	4s2.5s 2S → 4s2.49p 2P*	Measured	NIST
424.5675 nm	N/A	Ga I	emission	4s2.5s 2S → 4s2.48p 2P*	Measured	NIST
424.5675 nm	N/A	Ga I	emission	4s2.5s 2S → 4s2.48p 2P*	Measured	NIST
424.6112 nm	N/A	Ga I	emission	4s2.5s 2S → 4s2.47p 2P*	Measured	NIST
424.6112 nm	N/A	Ga I	emission	4s2.5s 2S → 4s2.47p 2P*	Measured	NIST
424.6563 nm	N/A	Ga I	emission	4s2.5s 2S → 4s2.46p 2P*	Measured	NIST
424.6563 nm	N/A	Ga I	emission	4s2.5s 2S → 4s2.46p 2P*	Measured	NIST
424.7046 nm	N/A	Ga I	emission	4s2.5s 2S → 4s2.45p 2P*	Measured	NIST
424.7046 nm	N/A	Ga I	emission	4s2.5s 2S → 4s2.45p 2P*	Measured	NIST
424.7569 nm	N/A	Ga I	emission	4s2.5s 2S → 4s2.44p 2P*	Measured	NIST
424.7569 nm	N/A	Ga I	emission	4s2.5s 2S → 4s2.44p 2P*	Measured	NIST
424.8143 nm	N/A	Ga I	emission	4s2.5s 2S → 4s2.43p 2P*	Measured	NIST
424.8143 nm	N/A	Ga I	emission	4s2.5s 2S → 4s2.43p 2P*	Measured	NIST
424.8743 nm	N/A	Ga I	emission	4s2.5s 2S → 4s2.42p 2P*	Measured	NIST
424.8743 nm	N/A	Ga I	emission	4s2.5s 2S → 4s2.42p 2P*	Measured	NIST
424.94 nm	N/A	Ga I	emission	4s2.5s 2S → 4s2.41p 2P*	Measured	NIST
424.94 nm	N/A	Ga I	emission	4s2.5s 2S → 4s2.41p 2P*	Measured	NIST
425.4789 nm	N/A	Ga I	emission	4s2.5s 2S → 4s2.34d 2D	Measured	NIST
425.4799 nm	N/A	Ga I	emission	4s2.5s 2S → 4s2.34d 2D	Measured	NIST
426.035 nm	N/A	Ga I	emission	4s2.5s 2S → 4s2.30d 2D	Measured	NIST
426.0365 nm	N/A	Ga I	emission	4s2.5s 2S → 4s2.30d 2D	Measured	NIST
426.6348 nm	N/A	Ga I	emission	4s2.5s 2S → 4s2.27d 2D	Measured	NIST
426.6367 nm	N/A	Ga I	emission	4s2.5s 2S → 4s2.27d 2D	Measured	NIST
427.1688 nm	N/A	Ga I	emission	4s2.5s 2S → 4s2.25d 2D	Measured	NIST
427.1712 nm	N/A	Ga I	emission	4s2.5s 2S → 4s2.25d 2D	Measured	NIST
427.8589 nm	N/A	Ga I	emission	4s2.5s 2S → 4s2.23d 2D	Measured	NIST
427.8621 nm	N/A	Ga I	emission	4s2.5s 2S → 4s2.23d 2D	Measured	NIST
428.7731 nm	N/A	Ga I	emission	4s2.5s 2S → 4s2.21d 2D	Measured	NIST
428.7774 nm	N/A	Ga I	emission	4s2.5s 2S → 4s2.21d 2D	Measured	NIST
429.3459 nm	N/A	Ga I	emission	4s2.5s 2S → 4s2.20d 2D	Measured	NIST
429.3507 nm	N/A	Ga I	emission	4s2.5s 2S → 4s2.20d 2D	Measured	NIST
430.0203 nm	N/A	Ga I	emission	4s2.5s 2S → 4s2.19d 2D	Measured	NIST
430.026 nm	N/A	Ga I	emission	4s2.5s 2S → 4s2.19d 2D	Measured	NIST
448.84 nm	N/A	ID 505	emission	5p 2P* → 5d 2D	Measured	NIST
459.16 nm	N/A	ID 505	emission	5s 2S → 5p 2P*	Measured	NIST
557 nm	N/A	ID 482	emission	1s.5s 3S → 1s.5p 3P*	Measured	NIST
567.7 nm	N/A	ID 498	emission	3s2.3p2 3P → 3s2.3p2 3P	Measured	NIST
587 nm	N/A	ID 482	emission	1s.4p 3P* → 1s.4d 3D	Measured	NIST
675 nm	N/A	ID 486	emission	3s2.3p3 2D* → 3s2.3p3 2D*	Measured	NIST
706.7 nm	N/A	ID 505	emission	4p 2P* → 4d 2D	Measured	NIST

Extended Properties

Covalent Radii (Extended)

Covalent radius (Pyykkö)

Covalent radius (Pyykkö, double)

Covalent radius (Pyykkö, triple)

Van der Waals Radii

Bondi

Batsanov

Alvarez

UFF

MM3

Dreiding

Atomic & Metallic Radii

Atomic radius (Rahm)

Metallic radius (C12)

Numbering Scales

Mendeleev

Pettifor

Glawe

Electronegativity Scales

Ghosh

Miedema

Gunnarsson–Lundqvist

Robles–Bartolotti

Polarizability & Dispersion

Dipole polarizability

Dipole polarizability (unc.)

C₆

C₆ (Gould–Bučko)

Miedema Parameters

Miedema molar volume

Miedema electron density

Supply Risk & Economics

Production concentration

Relative supply risk

Political stability (top producer)

Phase Transitions & Allotropes

Melting point	302.91 K
Boiling point	2502.15 K
Triple point (temperature)	302.92 K

Oxidation State Categories

−4 extended

−5 extended

+2 extended

−1 extended

−3 extended

−2 extended

+1 extended

0 extended

+3 main

Advanced Reference Data

Screening Constants (8)

n	Orbital	σ
1	s	0.6906
2	p	3.9092
2	s	8.401
3	d	15.9067
3	p	14.7964
3	s	14.0038
4	p	24.7784
4	s	23.9332

Crystal Radii Detail (3)

Charge	CN	r_crystal (pm)	Origin
3	IV	61
3	V	69
3	VI	76	from r^3 vs V plots,

Isotope Decay Modes (51)

Isotope	Mode	Intensity
56	p	—
57	p	—
58	p	—
59	p	—
60	B+	100%
60	B+p	1.6%
60	B+A	0%
61	B+	100%
61	B+p	0.3%
62	B+	100%

X‑ray Scattering Factors (506)

Energy (eV)	f₁	f₂
10	—	2.98527
10.1617	—	2.98141
10.3261	—	2.97756
10.4931	—	2.9737
10.6628	—	2.96986
10.8353	—	2.96602
11.0106	—	2.95695
11.1886	—	2.90859
11.3696	—	2.86103
11.5535	—	2.81425

Additional Data

Estimated Crustal Abundance

The estimated element abundance in the earth's crust.

1.9×101 milligrams per kilogram

References (1)

[5] Gallium https://education.jlab.org/itselemental/ele031.html

Estimated Oceanic Abundance

The estimated element abundance in the earth's oceans.

3×10-5 milligrams per liter

References (1)

[5] Gallium https://education.jlab.org/itselemental/ele031.html

Sources

Sources of this element.

Gallium is often found as a trace element in diaspore, sphalerite, germanite, bauxite, and coal. Some flue dusts from burning coal have been shown to contain as much 1.5 percent gallium.

References (1)

[6] Gallium https://periodic.lanl.gov/31.shtml

References

(9)

1 PubChem

Data deposited in or computed by PubChem

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2 Atomic Mass Data Center (AMDC), International Atomic Energy Agency (IAEA)

The half-life and atomic mass data was provided by the Atomic Mass Data Center at the International Atomic Energy Agency.

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3 IUPAC Commission on Isotopic Abundances and Atomic Weights (CIAAW)

Gallium

Element data are cited from the Atomic weights of the elements (an IUPAC Technical Report). The IUPAC periodic table of elements can be found at https://iupac.org/what-we-do/periodic-table-of-elements/. Additional information can be found within IUPAC publication doi:10.1515/pac-2015-0703 Copyright © 2020 International Union of Pure and Applied Chemistry.

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4 IUPAC Periodic Table of the Elements and Isotopes (IPTEI)

The information are cited from Pure Appl. Chem. 2018; 90(12): 1833-2092, https://doi.org/10.1515/pac-2015-0703.

Visit source License

License note: Copyright (c) 2020 International Union of Pure and Applied Chemistry. The International Union of Pure and Applied Chemistry (IUPAC) contribution within Pubchem is provided under a CC-BY-NC-ND 4.0 license, unless otherwise stated.

5 Jefferson Lab, U.S. Department of Energy

Gallium

Thomas Jefferson National Accelerator Facility (Jefferson Lab) is one of 17 national laboratories funded by the U.S. Department of Energy. The lab's primary mission is to conduct basic research of the atom's nucleus using the lab's unique particle accelerator, known as the Continuous Electron Beam Accelerator Facility (CEBAF). For more information visit https://www.jlab.org/

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License note: Please see citation and linking information: https://education.jlab.org/faq/index.html

6 Los Alamos National Laboratory, U.S. Department of Energy

Gallium

The periodic table at the LANL (Los Alamos National Laboratory) contains basic element information together with the history, source, properties, use, handling and more. The provenance data may be found from the link under the source name.

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7 NIST Physical Measurement Laboratory

Gallium

The periodic table contains NIST's critically-evaluated data on atomic properties of the elements. The provenance data that include data for atomic spectroscopy, X-ray and gamma ray, radiation dosimetry, nuclear physics, and condensed matter physics may be found from the link under the source name. Ref: https://www.nist.gov/pml/atomic-spectra-database

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8 PubChem Elements

Gallium

This section provides all form of data related to element Gallium.

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9 PubChem Elements

Gallium

The element property data was retrieved from publications.

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Last updated: May 1, 2026