Gallium (Ga) is a chemical element with atomic number 31. There are two stable gallium isotopes, ⁶⁹Ga and ⁷¹Ga. The most abundant one is ⁶⁹Ga.

Gallium is primarily used in the semiconductor industry, but it can also be used in glass thermometers (similarly to mercury) thanks to its fairly low melting point. Unlike mercury, gallium is non-toxic.