Gallium (Ga)

Stable isotopes of gallium available from ISOFLEX

Isotope Z(p) N(n) Atomic Mass Natural Abundance Enrichment Level Chemical Form
Ga-69  31  38  68.925581 60.11%  ≥99.60% Metal
Ga-69 31 38 68.925581 60.11% ≥99.60% Oxide
Ga-71  31  40  70.924707 39.89%  ≥99.80%  Metal
Ga-71 31 40 70.924707 39.89% ≥99.80% Oxide

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Gallium was discovered in 1875 by Paul-Émile Lecoq de Boisbaudran. It takes its name from the Latin name Gallia, meaning “France,” and possibly also from the Latin word gallus, meaning “rooster” (and reflecting the discoverer's name, Lecoq). It is one of the few metals that can be liquid near room temperature, which makes it an effective feature of high-temperature thermometers. It can be undercooled to almost 0 °C without solidifying, and it is actually more dense as a liquid than as a solid.

Gallium is a gray orthogonal crystal or silvery liquid. It is soluble in acids and alkalis and slightly soluble in mercury. It reacts with most metals at high temperatures. Gallium exists in a liquid state in the widest temperature range. Chemical properties of gallium fall between those of aluminum and indium. It combines with phosphorus, arsenic and antimony, forming the corresponding binary compounds, which exhibit interesting semiconductor properties.

The most important use of gallium is as a doping agent for semiconductors, transistors and other solid-state devices. Some gallium compounds also have major applications in electroluminescent light emission, microwave generation and UV-activated powder phosphors. Another important use of gallium, in oxide form, involves the spectroscopic analysis of uranium oxide. Gallium also is used to make many low-melting alloys. Some other uses for gallium are in high-vacuum systems as a liquid sealant, as a heat-transfer medium, and to produce mirrors on glass surfaces.

Properties of Gallium

Name Gallium 
Symbol Ga
Atomic number 31 
Atomic weight 69.723 
Standard state Solid at 298 °K 
CAS Registry ID 7440-55-3 
Group in periodic table 13 
Group name None 
Period in periodic table
Block in periodic table p-block 
Color Silvery white or gray
Classification Metallic 
Melting point 29.6 °C
Boiling point 2403 °C
Thermal conductivity 28.1 W/(m·K) at 302.93 °K 
Electrical resistivity 17.4 µΩ·cm at 20 °C 
Electronegativity 1.6 
Specific heat 0.372 J/g mol at 20 °C 
Heat of vaporization 256 kJ·mol-1 
Heat of fusion 5.59 kJ·mol-1
Density of liquid 6.095 g/cm
Density of solid 5.91 g/cm
Electron configuration [Ar]3d104s24p
Ionic radius  Ga3+: 1.13 Å 
Most common oxidation state +3 (also exhibits +2 and +1)

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