Indium
post-transition metal · period 5 · group 13 · p-block
Indium is a chemical element with the symbol In and atomic number 49. Indium is the softest metal that is not an alkali metal.
What the numbers say
At standard temperature and pressure Indium is a solid, sitting in period 5, group 13 of the p-block.
Its melting point of 430 K (157 °C) is the 86th highest of the 110 elements with a measured value — mid-range among the elements.
At 7.31 g/cm³ it is the 45th densest of 96 elements with a quoted density.
Pauling electronegativity is 1.78. Paired with oxygen (3.44) that is a difference of 1.66, which puts the bond polar covalent — oxides here tend to be semiconducting or refractory rather than salt-like.
In the solid state it takes a centered tetragonal structure.
It is reported in 3 oxidation states (1, 2, 3), which sets how many distinct compounds and phases it can form.
First identified in 1863.
Crystal structure
Solid Indium adopts a Centered Tetragonal arrangement, in the Tetragonal system — axes a = b ≠ c, angles α = β = γ = 90°. Symmetry controls the anisotropy of stiffness and thermal expansion, and the available slip systems set how far the metal deforms before it fractures.
Check it against computed structures
The structure search queries the Materials Project, OQMD and the Open Materials Database for computed crystal structures containing In — with DFT formation energy, hull stability and band gap where the provider publishes them.
K 2 · L 8 · M 18 · N 18 · O 3
Properties
| Atomic number | 49 |
|---|---|
| Atomic mass | 114.8181 u |
| Series | post-transition metal |
| Group | 13 |
| Period | 5 |
| Block | p-block |
| Phase at STP | Solid |
| Density | 7.31 g/cm³ |
| Melting point | 429.75 K (157 °C) |
| Boiling point | 2345 K (2072 °C) |
| Electronegativity (Pauling) | 1.78 |
| Electron configuration | [Kr] 4d¹⁰ 5s² 5p¹ |
| Crystal structure | Centered Tetragonal |
| Oxidation states | 1,2,3 |
| Discovered | 1863 |
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See In in context with all 118 elements.
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