76

Os

Osmium
190.23 (3)
Historical Information

Osmium was discovered in 1803 by Smithson Tennant in the dark coloured residue left when crude platinum is dissolved by aqua regia (a mixture of hydrochloric and nitric acid). This dark residue contains both osmium (named after osme meaning odour) and iridium.
Basic Information Shells
  • Name: Osmium
  • Symbol: Os
  • Atomic number: 76
  • Atomic weight: 190.23 (3)
  • Standard state: solid at 298 K
  • Group in periodic table: 8
  • Group name:Precious metal or Platinum group metal
  • Period in periodic table: 6
  • Block in periodic table: d-block
  • Classification: Metallic
 osmium
Uses Trivia
  • platinum/osmium 90/10 alloy is used in implants such as pacemakers and replacement valves

Osmium metal is lustrous, bluish white, extremely hard, and brittle even at high temperatures. It has the highest melting point and lowest vapour pressure of the platinum group.