Indium (In)
Indium is element 49, a post-transition metal in period 5, group 13 of the periodic table. At room temperature it is a solid.
Electron configuration [Kr] 4d10 5s2 5p1
Electrons per shell 2, 8, 18, 18, 3
Indium data
| Atomic number | 49 |
|---|---|
| Symbol | In |
| Atomic mass | 114.818 u |
| Category | Post-transition metal |
| Group | 13 |
| Period | 5 |
| Block | p |
| State at 25 °C | solid |
| Melting point | 430 K (156.9 °C) |
| Boiling point | 2345 K (2071.9 °C) |
| Density | 7.31 g/cm³ |
| Electronegativity (Pauling) | 1.78 |
| Atomic radius | 144 pm |
| 1st ionization energy | 558 kJ/mol |
| Electron affinity | -29 kJ/mol |
| Oxidation states | +1, +2, +3 |
| Common ion charge | 3+ |
| Discovered | 1863 |
Orbital diagram
Each box is one orbital holding up to two electrons of opposite spin. Following Hund’s rule, electrons spread out singly across a subshell before pairing.
Work through indium’s configuration and its ions →
Where indium sits
Indium belongs to the post-transition metals. Its Pauling electronegativity of 1.78 is mid-range; see the electronegativity chart and periodic trends for context. To use its mass in a calculation, try the molar mass calculator.
Indium FAQ
What is the electron configuration of indium?
Indium (Z = 49) has the configuration 1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p6 4d10 5s2 5p1. In noble-gas shorthand that is [Kr] 4d10 5s2 5p1.
How many valence electrons does indium have?
3 (outer shell (n = 5)).
What is the atomic mass of indium?
The standard atomic weight of indium is 114.818 u, so one mole weighs 114.818 g.
Is indium a metal?
Yes. Indium is a post-transition metal.
What is the charge of a indium ion?
Indium most commonly forms In3+.