Atomic number: 49

Symbol: In

Category: post transition metal

Density at 25°C: solid:  7.31 g·cm−3

Indium was initially used for high performance bearings in aircraft during WWII but today compounds with indium are primarily used as part of LEDs and even in transparent conductive surfaces. The name comes from indigo blue, from the spectral line that was observed when it was first discovered.

Indium wire. image: adapted from wikipedia

Indium's current primary application is to form transparent electrodes from indium tin oxide (ITO) in liquid crystal displays and touch screens.

Use, natural applications or common combinations: 

  • Semi conductors
  • For special sealants for cryogenics

Basic characteristics:

  • Standard atomic weight: 114.818(3)
  • Melting point: 156.5985 °C
  • Boiling point: 2072 °C
  • Radioactivity: most is slightly radioactive (a bit unusual for a stable element)
  • 115In ( 95.7%) decays via beta- ( emitting an electron)