49
In
Indium
114.818
Indium (In)
Post-Transition MetalGroup 13Period 5p-block-block
Indium is a chemical element with symbol In and atomic number 49. It is a post-transition metallic element that is rare in Earth's crust. The metal is very soft, malleable and easily fusible, with a melting point higher than sodium, but lower than lithium or tin.
Latin name: Indium
Atomic Number
49
Atomic Mass
114.818 g/mol
Phase (STP)
Solid
Electron Config.
[Kr] 4d¹⁰ 5s² 5p¹
General
SymbolIn
Atomic Number49
Atomic Mass114.818 g/mol
CategoryPost-Transition Metal
Group13
Period5
Blockp-block
Electron Configuration[Kr] 4d¹⁰ 5s² 5p¹
Valence Electrons13
Coloursilvery lustrous metallic
Appearancesilvery lustrous gray
CAS NumberCAS7440-74-6
Physical Properties
Phase (STP)Solid
Density7.31 g/cm³
Melting Point156.60°C · 313.88°F · 429.75 K
Boiling Point2071.85°C · 3761.33°F · 2345.00 K
Atomic Properties
Atomic Radius156 pm
Electronegativity1.78 Pauling
Ionization Energy558 kJ/mol
Oxidation States+3, +1
Ion ChargeIn3+/In+
Thermodynamic
Molar Heat26.74 J/(mol·K)
Crystal Structure
Crystal Structuretetragonal
Mechanical Properties
Mohs Hardness1.2
Abundance
In Universe0.00002%
In Sun0.00002%
In Earth's Crust0.000016%
Discovery & History
Discovery Year1863
Discovered ByFerdinand Reich, Hieronymous Richter
Country of DiscoveryGermany
Isotopes of Indium
| Isotope | Abundance | Half-life | Decay |
|---|---|---|---|
| In-113 | 4.281% | Stable | — |
| In-115 | 95.719% | 4.41 × 10¹⁴ years | β⁻ |