Science Education Home Home Teachers Students Games Videos VA SOL Programs

It's Elemental

The Element Osmium

[Click for Isotope Data]


76 Os Osmium 190.23

Atomic Number: 76

Atomic Weight: 190.23

Melting Point: 3306 K (3033°C or 5491°F)

Boiling Point: 5285 K (5012°C or 9054°F)

Density: 22.57 grams per cubic centimeter

Phase at Room Temperature: Solid

Element Classification: Metal

Period Number: 6

Group Number: 8

Group Name: none

What's in a name? From the Greek word for a smell, osme.

Say what? Osmium is pronounced as OZ-mee-em.

History and Uses:

Osmium and iridium were discovered at the same time by the British chemist Smithson Tennant in 1803. Osmium and iridium were identified in the black residue remaining after dissolving platinum ore with aqua regia, a mixture of 25% nitric acid (HNO3) and 75% hydrochloric acid (HCl). Today, osmium is primarily recovered during the processing of platinum and nickel ores.

Metallic osmium is hard, brittle and very difficult to make. Powdered osmium is easier to make but emits osmium tetroxide (OsO4) when it is exposed to the air. Unfortunately, osmium tetroxide smells bad and is very poisonous. Because of these problems, osmium is primarily used to make very hard alloys. Osmium alloys can be found in ball point pen tips, fountain pen tips, record player needles, electrical contacts and other devices where frictional wear must be minimized.

Estimated Crustal Abundance: 1.5×10-3 milligrams per kilogram

Estimated Oceanic Abundance: Not Applicable

Number of Stable Isotopes: 5 (View all isotope data)

Ionization Energy: 8.7 eV

Oxidation States: +4, +3

Electron Shell Configuration:


2s2   2p6

3s2   3p6   3d10

4s2   4p6   4d10   4f14

5s2   5p6   5d6


Citation and linking information

For questions about this page, please contact Steve Gagnon.