---
title: "Indium (In): Atomic Mass, Electron Configuration & Properties"
url: https://www.moldraw.com/elements/indium.html
description: "Indium (In), element 49: atomic mass 114.82, electron configuration [Kr] 4d¹⁰ 5s² 5p¹, group 13, period 5, p-block post-transition metal. Melting and boiling point, density, electronegativity and shells."
lang: en
publisher: Scidart Academy
generated: 2026-11-03
---
49In114.82

# Indium (In) – element 49

Indium is a chemical element with the symbol **In** and atomic number **49**. It is a post-transition metal in group 13, period 5 of the periodic table (p-block), and is a solid at room temperature.

Indium (In) has atomic number 49, atomic mass 114.82 u and electron configuration [Kr] 4d10 5s2 5p1.

[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)

## Indium facts

| Symbol | In |
| --- | --- |
| Atomic number | 49 |
| Atomic mass | 114.82 u (g/mol) |
| Category | post-transition metal |
| Group | group 13 |
| Period | 5 |
| Block | p-block |
| Phase at 20 °C | Solid |
| Electron configuration | 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d10 5p1 |
| Noble-gas notation | [Kr] 4d10 5s2 5p1 |
| Electrons per shell | 2, 8, 18, 18, 3 |
| Valence electrons | 3 |

## Bohr model and shells

Indium has 49 electrons in 5 shells: 2, 8, 18, 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 | 429.748 K (156.6 °C) |
| --- | --- |
| Boiling point | 2345 K (2071.8 °C) |
| Density | 7.31 g/cm³ |
| Electronegativity (Pauling) | 1.78 |
| Electron affinity | 37.043 kJ/mol |
| Ionization energies | 558.3, 1820.7, 2704 kJ/mol (1st, 2nd, 3rd) |
| Molar heat capacity | 26.74 J/(mol·K) |
| Discovered by | Ferdinand Reich |

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 In.

## Position in the periodic table

Tap any element to open its page.

## Frequently asked questions

### What is the atomic mass of indium?

The atomic mass of indium is 114.82 u, so one mole of indium atoms weighs 114.82 g.

### What is the electron configuration of indium?

Indium has 49 electrons: 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁶ 5s² 4d¹⁰ 5p¹, or [Kr] 4d¹⁰ 5s² 5p¹ in noble-gas notation. Electrons per shell: 2, 8, 18, 18, 3.

### How many valence electrons does indium have?

Indium has 3 valence electrons (group 13).

### Is indium a metal?

Yes. Indium is a post-transition metal.

### Where is indium on the periodic table?

Indium is in group 13, period 5, 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.