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.
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.
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 for any formula containing In.
Position in the periodic table
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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 (CC BY-SA 3.0); standard atomic weights from IUPAC (abridged). Values in brackets are the mass number of the longest-lived isotope.