---
title: "Gallium (Ga): Atomic Mass, Electron Configuration & Properties"
url: https://www.moldraw.com/elements/gallium.html
description: "Gallium (Ga), element 31: atomic mass 69.723, electron configuration [Ar] 3d¹⁰ 4s² 4p¹, group 13, period 4, p-block post-transition metal. Melting and boiling point, density, electronegativity and shells."
lang: en
publisher: Scidart Academy
generated: 2026-11-03
---
31Ga69.723

# Gallium (Ga) – element 31

Gallium is a chemical element with the symbol **Ga** and atomic number **31**. It is a post-transition metal in group 13, period 4 of the periodic table (p-block), and is a solid at room temperature.

Gallium (Ga) has atomic number 31, atomic mass 69.723 u and electron configuration [Ar] 3d10 4s2 4p1.

[Download periodic table PDF](https://www.moldraw.com/printables/periodic-table.pdf)[Open interactive periodic table](https://www.moldraw.com/tools/free-chem-tools/interactive-periodic-table.html)

## Gallium facts

| Symbol | Ga |
| --- | --- |
| Atomic number | 31 |
| Atomic mass | 69.723 u (g/mol) |
| Category | post-transition metal |
| Group | group 13 |
| Period | 4 |
| Block | p-block |
| Phase at 20 °C | Solid |
| Electron configuration | 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p1 |
| Noble-gas notation | [Ar] 3d10 4s2 4p1 |
| Electrons per shell | 2, 8, 18, 3 |
| Valence electrons | 3 |

## Bohr model and shells

Gallium has 31 electrons in 4 shells: 2, 8, 18, 3. Full configuration and noble-gas notation are in the table; work out any element or ion with the [electron configuration calculator](https://www.moldraw.com/tools/free-chem-tools/electron-configuration-calculator.html).

## Physical and atomic properties

| Melting point | 302.915 K (29.8 °C) |
| --- | --- |
| Boiling point | 2673 K (2399.8 °C) |
| Density | 5.91 g/cm³ |
| Electronegativity (Pauling) | 1.81 |
| Electron affinity | 41 kJ/mol |
| Ionization energies | 578.8, 1979.3, 2963 kJ/mol (1st, 2nd, 3rd) |
| Molar heat capacity | 25.86 J/(mol·K) |
| Discovered by | Lecoq de Boisbaudran |

Use the atomic mass in the [molar mass calculator](https://www.moldraw.com/tools/free-chem-tools/molar-mass-calculator.html) for any formula containing Ga.

## Position in the periodic table

Tap any element to open its page.

## Frequently asked questions

### What is the atomic mass of gallium?

The atomic mass of gallium is 69.723 u, so one mole of gallium atoms weighs 69.723 g.

### What is the electron configuration of gallium?

Gallium has 31 electrons: 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p¹, or [Ar] 3d¹⁰ 4s² 4p¹ in noble-gas notation. Electrons per shell: 2, 8, 18, 3.

### How many valence electrons does gallium have?

Gallium has 3 valence electrons (group 13).

### Is gallium a metal?

Yes. Gallium is a post-transition metal.

### Where is gallium on the periodic table?

Gallium is in group 13, period 4, in the p-block.

Data: [Periodic-Table-JSON](https://github.com/Bowserinator/Periodic-Table-JSON) (CC BY-SA 3.0); standard atomic weights from IUPAC (abridged). Values in brackets are the mass number of the longest-lived isotope.