---
title: "Indium (In) — element 49"
description: "Indium is element 49, symbol In, atomic weight 114.82. Configuration, properties, uses and neighbours."
url: https://atoneplace.net/element/indium/
site: "At One Place"
---

# Indium (In)

**Indium — element 49: In**

114.82 u · Post-transition metal · period 5, group 13

Indium tin oxide is the material that made touchscreens possible: a coating that conducts electricity while being close to transparent, which almost nothing else does well. The metal is so soft it can be scratched with a fingernail and it screams faintly when bent, a crackling called the indium cry, caused by crystal twinning — tin does the same thing. It is produced entirely as a by-product of zinc refining, so world output is capped by how much zinc the world wants rather than by demand for indium.

## Properties

- **Atomic number:** 49
- **Symbol:** In
- **Standard atomic weight:** 114.82 u
- **Category:** Post-transition metal
- **Group:** 13
- **Period:** 5
- **Block:** p-block
- **Electron configuration:** [Kr] 5s² 4d¹⁰ 5p¹
- **Electrons per shell:** 2, 8, 18, 18, 3
- **Melting point:** 429.75 K — 156.6 °C — 313.9 °F
- **Boiling point:** 2,345 K — 2071.8 °C — 3761.3 °F
- **Density:** 7.31 g/cm³
- **Electronegativity:** 1.78 (Pauling)
- **Oxidation states:** +3
- **Discovered:** 1863 by Ferdinand Reich and Hieronymous Theodor Richter

## Electron configuration

- **Full:** 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁶ 5s² 4d¹⁰ 5p¹
- **Noble gas shorthand:** [Kr] 5s² 4d¹⁰ 5p¹
- **Shells:** K: 2 · L: 8 · M: 18 · N: 18 · O: 3

## What it is used for

- Indium tin oxide, the transparent conductor on every touchscreen and LCD
- Cold-weld seals and gaskets for ultra-high vacuum systems
- Low-melting alloys and thermal interface material
- Semiconductor compounds for infrared detectors and high-speed transistors
- Solder for joining glass, ceramics and cryogenic assemblies

## Neighbours in the table

| Z | Element | Symbol | Mass |
| --- | --- | --- | --- |
| 47 | Silver | Ag | 107.87 |
| 48 | Cadmium | Cd | 112.41 |
| 49 | Indium ← | In | 114.82 |
| 50 | Tin | Sn | 118.71 |
| 51 | Antimony | Sb | 121.76 |

## Group 13

Elements in the same group share their outer electron count, which is why they behave similarly in reactions. Indium sits in group 13 with boron, aluminum, gallium, thallium, nihonium.

## Common questions

### What is the atomic number of indium?

49. That is the number of protons in its nucleus, which is what defines the element.

### What is the symbol for indium?

In.

### What is the electron configuration of indium?

1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁶ 5s² 4d¹⁰ 5p¹, or [Kr] 5s² 4d¹⁰ 5p¹ in noble-gas shorthand.

### What is the melting point of indium?

429.75 K — 156.6 °C — 313.9 °F

## Related pages

- [Silver (Ag)](https://atoneplace.net/element/silver/)
- [Cadmium (Cd)](https://atoneplace.net/element/cadmium/)
- [Tin (Sn)](https://atoneplace.net/element/tin/)
- [Antimony (Sb)](https://atoneplace.net/element/antimony/)
- [Boron (B)](https://atoneplace.net/element/boron/)
- [Aluminum (Al)](https://atoneplace.net/element/aluminum/)
- [Gallium (Ga)](https://atoneplace.net/element/gallium/)
- [Thallium (Tl)](https://atoneplace.net/element/thallium/)
- [Nihonium (Nh)](https://atoneplace.net/element/nihonium/)

## Sources

- Official vendor product documentation — At One Place (/about/)