Gallium (symbol Ga, atomic number 31) is a metal that melts in your hand, used in LEDs and high-speed electronics. It is classified as a post-transition metal and sits in group 13, period 4 of the periodic table.
Overview
Gallium is the chemical element with atomic number 31 and the symbol Ga. With a standard atomic weight of 69.723, it is a post-transition metal. In the periodic table it occupies group 13 and period 4, and under standard conditions it is normally a solid. Gallium is a metal that melts in your hand, used in LEDs and high-speed electronics.
Atomic structure
An atom of Gallium has 31 protons in its nucleus and, when neutral, 31 electrons arranged in the configuration [Ar] 3d10 4s2 4p1. Its standard atomic weight of 69.723 reflects the natural mix of its stable isotopes.
Discovery and place in the table
Gallium was discovered in 1875 by Lecoq de Boisbaudran. It follows Zinc (Zn) and precedes Germanium (Ge) in order of atomic number.
| Atomic number | 31 |
|---|---|
| Symbol | Ga |
| Atomic mass | 69.723 |
| Category | Post-transition metal |
| Group | 13 |
| Period | 4 |
| Electron configuration | [Ar] 3d10 4s2 4p1 |
| Phase at STP | Solid |
| Discovered | 1875 (Lecoq de Boisbaudran) |