Gallium
Definition and meaning of Gallium in chemistry.
![Gallium element card: symbol Ga, atomic number 31, atomic mass 69.723, electron configuration [Ar] 3d¹⁰ 4s² 4p¹, oxidation states +3, Post-transition metal, group 13, period 4, solid at room temperature.](/assets/images/terms/gallium-chemical-element.webp)
Gallium is a soft, silvery post-transition metal with the chemical symbol Ga and atomic number 31. It is famous for having a remarkably low melting point. The solid metal can literally melt into a liquid when held in a warm human hand.
In more detail
Gallium is located in group 13 of the periodic table. It does not occur in nature as a free, uncombined element. Instead, mining companies extract it in trace amounts as a valuable byproduct.
They typically isolate it while processing bauxite and zinc ores. The highly pure solid metal fractures conchoidally, shattering much like glass. However, gallium expands by over three percent when freezing from its liquid state.
This unusual structural property is shared only with water, silicon, and a few other substances. A common student misconception is that gallium behaves exactly like other metals when it freezes, but most metals contract instead. Gallium primarily forms chemical compounds in the +3 oxidation state.
It bonds covalently in many of its solid crystalline phases. Chemists have also observed +1 state compounds under specific laboratory conditions. Gallium is renowned among metallurgists for easily forming alloys with most other metals.
Adding gallium significantly reduces the melting points of these resulting alloys. This unique property helps engineers create specialized liquid metal coolants. Gallium also boasts unique and excellent semiconductor characteristics.
These traits have made it absolutely indispensable in modern microelectronics. Manufacturers rely on it to mass-produce optoelectronic devices and high-frequency integrated circuits.
Key facts
| Field | General Chemistry |
|---|---|
| Symbol | Ga |
| Atomic number | 31 |
| Atomic mass | 69.723 u |
| Category | Post-Transition-Metal |
| State at room temperature | Solid (melts slightly above ambient) |
| Melting point | 29.76 °C (85.58 °F) |
| Boiling point | 2204 °C (3999 °F) |
Gallium arsenide is an incredibly vital semiconductor compound. Technology companies use it heavily to manufacture high-efficiency light-emitting diodes, commonly known as LEDs. It is also an essential component for producing microwave frequency integrated circuits. These circuits are crucial for running modern cellular networks and satellite communication systems.
Frequently asked questions
Why does gallium melt in your hand?
Its melting point of 29.76 degrees Celsius is just below standard human body temperature. A human hand transfers enough thermal energy to trigger a phase change.
What happens when gallium contacts aluminum?
Liquid gallium rapidly permeates the grain boundaries of solid aluminum. This completely destroys its structural integrity and causes the aluminum metal to become extremely brittle.
Why does gallium expand when it freezes?
Gallium atoms form a crystalline structure when solidifying that takes up more volume than the liquid phase. This is an unusual property shared by very few substances, such as water.
Related terms
Sources & references
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