Transition metals
Osmium
The densest naturally occurring element, hard and bluish.
Atomic #76Mass190.23Blockd-blockPeriod6Group8
Os76 · 190.23
3D Atom Explorer
Inside the Osmium atom
Switch between Bohr and Quantum Cloud modes to compare a simple teaching model with a more realistic probability-based view, and follow the guided tour to explore the Osmium atom step by step.
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Electron configuration
[Xe] 4f14 5d6 6s2
A neutral Osmium atom has 76 electrons (equal to its proton count). Choosing a different isotope above changes only the neutron count.
Shell distribution
Shell 12 e⁻Shell 28 e⁻Shell 318 e⁻Shell 432 e⁻Shell 514 e⁻Shell 62 e⁻
Electrons fill inner shells before outer ones; the outermost (valence) shell drives the element's chemistry.
Properties
Physical & atomic properties
- State (room temp)
- Solid
- Melting point
- 3306 K (3033 °C)
- Boiling point
- 5285 K (5012 °C)
- Density
- 22.59 g/cm³
- Electronegativity
- 2.2 Pauling
- Atomic radius
- 130 pm
- 1st ionization energy
- 840 kJ/mol
- Category
- Transition metals
History
Discovery & naming
- Discovered
- 1803
- Discovered by
- Smithson Tennant
- Origin of name
- Greek 'osme', meaning smell.
Notable uses
Extremely hard alloys and fountain-pen tips (densest element).
Cosmic origin
Where Osmium comes from
Neutron star mergers
Dominated by rapid neutron capture in neutron-rich cosmic collisions.
Simplified origin map — many elements form through more than one astrophysical pathway.
Summary
- Atomic number
- 76
- Atomic mass
- 190.23
- Category
- Transition metals
- Group · Period
- 8 · 6
- Block
- d-block
- Shells
- 2 · 8 · 18 · 32 · 14 · 2