In
Indium
Element 49 · Post-transition metal
Indium (In)
Indium is a very soft, silvery metal that squeaks when bent. Indium tin oxide makes touchscreens possible.
- Post-transition metal
- Period 5
- Group 13
- p-block
- solid at room temperature
Key properties
- Atomic mass
- 114.818
- u
- Electron configuration
- [Kr] 4d10 5s2 5p1
- Melting point
- 156.6 °C
- 429.75 K
- Boiling point
- 2,071.9 °C
- 2,345 K
- Density
- 7.31 g/cm³
- Electronegativity
- 1.78
- Pauling
- Atomic radius
- 193 pm
- van der Waals
- 1st ionisation energy
- 5.786 eV
Compare with every element:Electronegativity chartAtomic radius chartIonisation energy chartDensity chart of the elementsMelting point chartElectron configuration chart
Did you know?
Notable facts about indium
- 01
Bending a bar of indium makes a high-pitched “cry”, like tin.
- 02
Indium tin oxide is both transparent and electrically conductive.
- 03
Indium wets glass and is used to make airtight seals.
Applications
What is indium used for?
- Touchscreens and LCDs (ITO)
- Low-melting solders
- Semiconductors
- Cryogenic seals
History
Discovery & name origin
Discovered by
Year
Where
Germany
Name origin
After the bright indigo line seen in its spectrum.
Atomic structure
Atomic properties
Atomic structure
Atomic properties
- Atomic number
- 49
- Atomic mass
- 114.818 u
- Group
- 13
- Period
- 5
- Block
- p-block
- Electron configuration
- [Kr] 4d10 5s2 5p1
- Full configuration
- 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d10 5p1
- Electrons per shell
- 2, 8, 18, 18, 3
- Electronegativity (Pauling)
- 1.78
- Electron affinity
- 0.3 eV
- Atomic radius (van der Waals)
- 193 pm
- Stable isotopes
- 1
Oxidation states
Highlighted: common oxidation states (+3).
Successive ionisation energies
Energy to remove each electron in turn (kJ/mol). Big jumps show where a new, inner shell begins.
- 1st558.3
- 2nd1,820.7
- 3rd2,704
- 4th5,210
Physical
Physical properties & colour
Physical
Physical properties & colour
- State at 20 °C
- Solid
- Melting point
- 429.75 K · 156.6 °C · 313.9 °F
- Boiling point
- 2,345 K · 2,071.9 °C · 3,761.3 °F
- Density
- 7.31 g/cm³
- Molar heat capacity
- 26.74 J/(mol·K)
- Appearance
- Silvery lustrous grey
- CPK model colour
- Copied
The CPK colour is the convention used for this element’s atoms in molecular models.
FAQ
Indium questions
What is In on the periodic table?
In is the symbol for indium, element 49 on the periodic table. It sits in group 13, period 5, in the post-transition metal category, and has an atomic mass of 114.818.
What is the atomic number of indium?
Indium has atomic number 49, so every indium atom has 49 protons in its nucleus. Its symbol is In and its atomic mass is 114.818.
Who discovered indium?
Indium was discovered by Ferdinand Reich and Hieronymous Theodor Richter in 1863 (Germany). The name comes from after the bright indigo line seen in its spectrum.
What is indium used for?
Indium is used for: touchscreens and LCDs (ITO); low-melting solders; semiconductors; cryogenic seals.
Is indium a metal?
Yes. Indium is a post-transition metal, one of the metallic elements.
What is the electron configuration of indium?
The electron configuration of indium is [Kr] 4d10 5s2 5p1. Its 49 electrons are arranged in shells as 2, 8, 18, 18, 3.