Name: gallium
Symbol: Ga
Atomic number: 31
Atomic weight: 69.723 (1)
Group in periodic table: 13
Group name:
Period in periodic table: 4
Block in periodic table: p-block
CAS registry ID: 7440-55-3
It is the only metal, except for mercury, caesium, and rubidium, which can be liquid near room temperatures; this makes possible its use in high-temperature thermometers. It has one of the longest liquid ranges of any metal and has a low vapour pressure even at high temperatures.
Ultra-pure gallium has a beautiful, silvery appearance, and the solid metal exhibits a conchoidal fracture similar to glass. The metal expands on solidifying; therefore, it should not be stored in glass or metal containers, as they may break as the metal solidifies.
High-purity gallium is attacked only slowly by mineral acids. Gallium arsenide is capable of converting electricity directly into coherent light and gallium arsenide is a key component of LEDs (light emitting diodes).