49114.82InIndium
Indium (In) — element 49post-transition metal · group 13, period 5
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 (the p-block), with a standard atomic mass of 114.82 u. At room temperature (25 °C) indium is a solid.
💡 Known for: Indium tin oxide (ITO) forms the transparent conductive layer in touchscreens and LCD displays.
# Indium properties
| Symbol | In |
|---|---|
| Atomic number | 49 |
| Atomic mass | 114.82 u |
| Category | post-transition metal |
| Group | 13 |
| Period | 5 |
| Block | p-block |
| Electron configuration | [Kr] 4d¹⁰ 5s² 5p¹ |
| Full configuration | 1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁶ 4d¹⁰ 5s² 5p¹ |
| Electrons per shell | 2, 8, 18, 18, 3 |
| Protons / electrons | 49 / 49 |
| State at 25 °C | solid |
| Melting point | 429.75 K (156.6 °C, 313.9 °F) |
| Boiling point | 2345 K (2071.8 °C, 3761.3 °F) |
| Density | 7.31 g/cm³ |
| Electronegativity (Pauling) | 1.78 |
| First ionization energy | 5.786 eV |
| Atomic radius | 156 pm |
| Discovered | 1863 |
# Electron configuration of indium
The electron configuration of indium is [Kr] 4d¹⁰ 5s² 5p¹, written out in full as 1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁶ 4d¹⁰ 5s² 5p¹. Its 49 electrons fill 5 shells as 2, 8, 18, 18, 3, so the outermost shell holds 3 electrons. As a group 13 element, indium has 3 valence electrons.
# Related elements
CdCadmiumprevious elementSnTinnext elementBBorongroup 13AlAluminiumgroup 13GaGalliumgroup 13TlThalliumgroup 13NhNihoniumgroup 13PbLeadpost-transition metalBiBismuthpost-transition metalPoPoloniumpost-transition metalFlFleroviumpost-transition metalMcMoscoviumpost-transition metalLvLivermoriumpost-transition metal
# Indium FAQ
What is the atomic number of indium?
The atomic number of indium is 49: every indium atom has 49 protons in its nucleus. Its symbol is In.
What is the atomic mass of indium?
The standard atomic mass of indium is 114.82 u.
What is the electron configuration of indium?
Indium's electron configuration is [Kr] 4d¹⁰ 5s² 5p¹ (1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁶ 4d¹⁰ 5s² 5p¹), with 2, 8, 18, 18, 3 electrons per shell.
Is indium a metal?
Yes. Indium is a post-transition metal, one of the metals.
What is the melting point of indium?
Indium melts at 429.75 K (156.6 °C, 313.9 °F) and boils at 2345 K (2071.8 °C, 3761.3 °F).
What is indium used for / known for?
Indium tin oxide (ITO) forms the transparent conductive layer in touchscreens and LCD displays.