Gallium (Ga)
Element 31 · Post-transition metal · Solid at 25 °C · Group 13, Period 4
Gallium melts at about 30 °C — a solid in your desk drawer, a liquid in your hand — and gallium compounds are the heart of LEDs and fast electronics.
On the periodic table, gallium sits in group 13 — the boron group — in period 4. It is one of 12 elements classified as a post-transition metal, and at room temperature (25 °C) it is a solid.
The post-transition metals sit between the transition metals and the metalloids. They are genuine metals — shiny and conductive — but softer, weaker, and lower-melting than the d-block metals, and their chemistry has more covalent character. Everyday examples from this family include aluminium foil, tin cans, and lead batteries.
Properties of gallium
| Atomic number (Z) | 31 |
|---|---|
| Symbol | Ga |
| Atomic mass | 69.723 |
| Category | Post-transition metal |
| Group | 13 |
| Period | 4 |
| Block | p-block |
| Metal / nonmetal | Metal |
| State at 25 °C | Solid |
| Electron configuration | [Ar] 3d10 4s2 4p1 |
| Electronegativity (Pauling) | 1.81 |
| Melting point | 29.76 °C (302.91 K / 85.57 °F) |
| Boiling point | 2,204 °C (2,477.15 K / 3,999.2 °F) |
| Density | 5.91 g/cm³ |
Position in the periodic table
Gallium shares group 13 — the boron group with Boron (B), Aluminium (Al), Indium (In), Thallium (Tl), Nihonium (Nh). Elements in the same group have the same number of outer electrons, so they tend to behave alike chemically — comparing them is one of the fastest ways to see periodic trends in action.
Physical properties
Gallium melts at 29.76 °C (302.91 K / 85.57 °F) and boils at 2,204 °C (2,477.15 K / 3,999.2 °F), giving it a liquid range of about 2,174.2 °C at standard pressure.
Its density is 5.91 g/cm³.
See also: the interactive periodic table, how to read the periodic table, metals, nonmetals & metalloids.