Osmium

Koushik 26/06/2026 19:58:08 Updated 26/06/2026 19:58:08

Property	Value
Atomic Number	76
Element	Osmium
Symbol	Os
Atomic Mass	190.23 u
Number of Neutrons	114 (most common isotope, Osmium-192)
Number of Protons	76
Number of Electrons	76
Period	6
Group	8
Phase	Solid
Radioactive	No
Natural	Yes
Metal	Yes
Nonmetal	No
Metalloid	No
Type	Transition Metal
Atomic Radius	185 pm
Electronegativity	2.20 (Pauling scale)
First Ionization Energy	8.438 eV
Density	22.59 g/cm³ (densest naturally occurring element)
Melting Point	3033 °C
Boiling Point	5012 °C
Number of Isotopes	7 stable (Os-184, Os-186, Os-187, Os-188, Os-189, Os-190, Os-192)
Discoverer	Smithson Tennant
Year	1803
Specific Heat	0.130 J/g·K
Number of Shells	6
Number of Valence Electrons	8