Osmium

Element 76 on the periodic table, symbol Os, group 8, period 6.

Osmium (from Greek osme (ὀσμή) meaning "smell") is a chemical element with symbol Os and atomic number 76. It is a hard, brittle, bluish-white transition metal in the platinum group that is found as a trace element in alloys, mostly in platinum ores. Osmium is the densest naturally occurring element, with a density of 22.59 g/cm3.

Appearance: silvery, blue cast

Properties

Atomic Number: 76
Atomic Mass: 190.2330 u
Group: 8
Period: 6
Block: d-block
Category: Transition Metal
State at 25 °C: Solid
Melting Point: 3,306 K · 3,032.9 °C
Boiling Point: 5,285 K · 5,011.9 °C
Density: 22.59 g/cm³
Atomic Radius: 130 pm
Electronegativity: 2.2
Oxidation States: +4, +8
Abundance in Crust: 0.002 mg/kg
Discovered: 1803
Discovered By: Smithson Tennant

Electron Configuration

[Xe] 4f14 5d6 6s2

1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d10 5p6 6s2 4f14 5d6

Ionisation Energies (kJ/mol)

1. 840
2. 1,600

Elements near Osmium

Elements in the same group share the number of outer electrons and behave in similar ways. Elements in the same period share a shell, so they change steadily from left to right.