Periodic Table of Elements




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.

Name: Indium
Symbol: In
Atomic number: 49
Atomic weight: 114.82
State: solid
Group, period, block: 13, 5, p
Color: silvery lustrous gray
Classification: post-transition metal
Electron configuration: 4d10 5s2 5p1

Physical properties

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

Atomic properties

Oxidation states: 3, 2, 1
Electronegativity: 1.78 (Pauling scale)
Ionization energies: 1st: 558.3 kJmol-1
Covalent radius: 1425 pm
Van der Waals radius: 193 pm
  • In
  • Electron Configuration


There are two naturally occurring isotopes of gallium exist, 113In, and 115In.