Indium was discovered by the German chemists Ferdinand Reich and Hieronymus Theodor Richter in Germany in 1863. Indium was named for the indigo blue line in its spectrum that was the first indication of its existence in zinc ores. Zinc ores are the primary source of indium, where it is found in compound form.
Atomic number: 49
Atomic weight: 114.82
Group, period, block: 13, 5, p
Color: silvery lustrous gray
Classification: post-transition metal
Electron configuration: 4d10 5s2 5p1
Density: 7.31 g/cm-3
Melting point: 429.7485 K, 156.5985 °C, 313.8773 °F
Boiling point: 2345 K, 2072 °C, 3762 °F
Oxidation states: 3, 2, 1
Electronegativity: 1.78 (Pauling scale)
Ionization energies: 1st: 558.3 kJ·mol-1
Covalent radius: 142±5 pm
Van der Waals radius: 193 pm
There are two naturally occurring isotopes of gallium exist, 113In, and 115In.