Gallium is the chemical element with symbol Ga and atomic number 31. It is a soft, silvery metal in group 13 that is famous for melting just above ordinary room temperature. Gallium is especially important in modern electronics because compounds such as gallium arsenide and gallium nitride are high-performance semiconductors.
Gallium quick facts
| Property | Value |
| Symbol | Ga |
| Atomic number | 31 |
| Relative atomic mass | 69.723 |
| Group | 13 |
| Period | 4 |
| Block | p-block |
| Density | 5.91 g/cm³ |
| Melting point | 29.7646°C |
| Boiling point | 2229°C |
| Electron configuration | [Ar] 3d¹⁰ 4s² 4p¹ |
| Common oxidation state | +3 |
| CAS number | 7440-55-3 |
| Stable natural isotopes | ⁶⁹Ga, ⁷¹Ga |
Position and electron configuration
Gallium is in group 13, period 4 and the p-block. Its electron configuration is [Ar] 3d¹⁰ 4s² 4p¹. The +3 oxidation state is dominant, although +1 compounds are also known.
See the complete CleverlySmart periodic table.
Why gallium melts in your hand
Gallium melts at only 29.7646°C, so a piece held in a warm hand may liquefy. Yet its boiling point is extremely high, giving gallium one of the widest liquid temperature ranges of any metal. Gallium also expands when it freezes, so solidification in rigid containers can cause damage.
Pure gallium can wet glass and some other surfaces. It can also diffuse into certain metals and weaken them, especially aluminium, so gallium should not be casually stored or handled in contact with aluminium equipment.
Important gallium compounds
- Gallium arsenide (GaAs): a direct-band-gap semiconductor used in high-frequency electronics, lasers, LEDs and high-efficiency solar cells.
- Gallium nitride (GaN): a wide-band-gap semiconductor crucial for blue and green LEDs, power electronics, radio-frequency devices and fast chargers.
- Gallium oxide (Ga₂O₃): an ultra-wide-band-gap material being developed for high-voltage power electronics and ultraviolet devices.
- Gallium salts: used in specialised chemical, medical and materials applications.
Occurrence and production
Gallium rarely forms concentrated ores. It is present in trace amounts in bauxite, zinc ores such as sphalerite, and some coal. Most commercial gallium is recovered as a by-product during aluminium or zinc processing rather than from dedicated gallium mines.
Uses of gallium
- LEDs and lasers: GaN and GaAs-based compounds convert electricity efficiently into light.
- High-frequency electronics: gallium semiconductors operate efficiently at microwave and radio frequencies.
- Power electronics: GaN devices can switch rapidly and operate at high electric fields.
- Solar cells: gallium-containing III-V semiconductors are used in very high-efficiency photovoltaic devices, including space applications.
- Low-melting alloys and thermometry: gallium alloys can remain liquid over useful temperature ranges.
Gallium isotopes
Natural gallium contains two stable isotopes, ⁶⁹Ga and ⁷¹Ga. Radioisotopes such as gallium-67 and gallium-68 are important in nuclear medicine, especially diagnostic imaging.
For broader isotope information, see the CleverlySmart isotope table.
Biological role and safety
Gallium has no known essential biological role. Metallic gallium is generally considered to have relatively low acute toxicity, but gallium compounds have different properties and should be handled according to their safety data. Semiconductor manufacturing materials may contain arsenic or other hazardous elements in addition to gallium.
Discovery and name
Dmitri Mendeleev predicted the existence and approximate properties of an element he called eka-aluminium. French chemist Paul-Émile Lecoq de Boisbaudran discovered gallium spectroscopically in 1875 and later isolated it. The name refers to Gallia, the Latin name for France.
Frequently asked questions
Does gallium really melt in your hand?
Yes. Its melting point is about 29.8°C, below normal body temperature.
What is gallium mainly used for?
Its most important modern uses are semiconductor compounds, especially GaAs and GaN, for electronics, LEDs, lasers and solar cells.
Low melting point and unusual metal behaviour
Gallium melts at about 29.76°C, so a small sample can melt in a warm hand, yet it boils only at a very high temperature. It also expands slightly on freezing and can wet glass and many other surfaces. Liquid gallium can embrittle certain metals, especially aluminium, so it should not be placed on structural aluminium parts.
Gallium in semiconductors and electronics
Gallium’s greatest technological importance comes from compounds rather than the pure metal. Gallium arsenide (GaAs) is used in high-frequency electronics, lasers and efficient solar cells, while gallium nitride (GaN) enables blue and ultraviolet LEDs and increasingly powerful high-frequency and power-electronic devices.
Gallium is usually recovered as a by-product of aluminium and zinc processing, so supply depends on the economics of other metals as well as gallium demand.
Frequently asked questions
Why does gallium melt in your hand?
Its melting point is slightly below normal body temperature.
Is gallium used in computer chips?
Yes, mainly as compounds such as GaAs and GaN where very fast electronics, optoelectronics or high-power operation are needed.
