Indium is named after indigo, which is the color of the light released by its atoms when electrified. Its ores are rare, and most of the metal is obtained from lead and zinc ores, such as esphalerite. Pure indium is very soft, and is mainly used in compound form. For example, a compound called indium tin oxide is used in touch screens. Also, indium is used in microchips and to produce heat- and glare-resistant soldering goggles and masks.

Summary of properties (In)

Atomic weight114.818(1)
Discoverer (year)Reich, Ferdinand & Richter, Hieronymus (1863)
Natural formmetallic solid (tetragonal)
Electron configuration[Kr] 4d10 5s2 5p1
Melting point (ºC)157
Boiling point (ºC)2000
Abundance in earth's crust (ppm)0.25
Isotope (abundance)113In (4.281), 115In (95.719)
Density g/cm37.31
Van der Waals radius (pm)193
Covalent radius (pm)142
Electronegativity (Pauling)1.78
Vaporization enthalpy (kJ/mol)226.40
Enthalpy of fusion (kJ/mol)3.28
Specific heat capacity (J/g·K) at 25ºC and 1 atm0.23
Thermal conductivity (W/cm·K) at 25ºC and 1 atm0.820
Oxidation state+3
Electron affinity (eV)0.30
1st Ionization potential (eV)5.7864

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