What is the noble-gas shorthand for osmium?

[Xe] 4f¹⁴ 5d⁶ 6s². The [Xe] core represents the filled 1s² through 5p⁶ subshells (54 electrons), leaving eight valence electrons: six in 5d and two in 6s.

How many valence electrons does osmium have?

Osmium has 8 valence electrons: 6 in the 5d subshell and 2 in the 6s subshell. This gives osmium access to oxidation states from +2 to +8, with +4 most common.

What is osmium's highest oxidation state?

Osmium reaches +8 in OsO₄ (osmium tetroxide), one of the highest oxidation states of any element. At +8 it has used all eight valence electrons. The +4 state (OsCl₄) is also stable.

Why is osmium the densest element?

Osmium's high nuclear charge (Z=76) combined with the lanthanide contraction — which compresses the atomic radius — results in an exceptionally dense packing of atoms in the hexagonal close-packed crystal lattice, giving osmium a density of 22.59 g/cm³.

What block and period is osmium in?

Osmium is in Period 6, Group 8 (VIII B), and belongs to the d-block of the periodic table. It is a platinum-group metal and one of the six platinum-group elements.

What are the quantum numbers for osmium's last electron?

The last (76th) electron of osmium occupies the 6s subshell with quantum numbers n=6, l=0, mₗ=0, mₛ=−½. It is the spin-down partner of the first 6s electron.

Osmium Electron Configuration

Name: Osmium Electron Configuration
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Interactive reference for osmium's electron configuration ([Xe] 4f¹⁴ 5d⁶ 6s²), orbital diagram, quantum numbers, and key atomic properties.

Z = 76 Os Osmium

Osmium — Electron Configuration

Atomic number 76 · Transition metal · Period 6, Group 8 · d-block · Platinum group

[Xe] 4f¹⁴ 5d⁶ 6s² 76 electrons 8 valence e⁻ +4 / +8 oxidation

Subshell Breakdown

Subshell	Type	Electrons	Max	Notation	In [Xe]?
1s	s, n=1	2	2	1s²	core
2s	s, n=2	2	2	2s²	core
2p	p, n=2	6	6	2p⁶	core
3s	s, n=3	2	2	3s²	core
3p	p, n=3	6	6	3p⁶	core
3d	d, n=3	10	10	3d¹⁰	core
4s	s, n=4	2	2	4s²	core
4p	p, n=4	6	6	4p⁶	core
4d	d, n=4	10	10	4d¹⁰	core
5s	s, n=5	2	2	5s²	core
5p	p, n=5	6	6	5p⁶	core
4f	f, n=4	14	14	4f¹⁴	valence
5d	d, n=5	6	10	5d⁶	valence
6s	s, n=6	2	2	6s²	valence
Total		76

Full Configuration

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

All 14 subshells written explicitly.

Noble-Gas Shorthand

[Xe] 4f¹⁴ 5d⁶ 6s²

[Xe] = 1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁶ 4d¹⁰ 5s² 5p⁶ (54 electrons).

Subshell Explorer

Click a subshell button to inspect its electrons and orbital details.

Shell Fill Summary

Shell 1 (n=1) — 1s² 2 / 2 electrons (100%)

Shell 2 (n=2) — 2s² 2p⁶ 8 / 8 electrons (100%)

Shell 3 (n=3) — 3s² 3p⁶ 3d¹⁰ 18 / 18 electrons (100%)

Shell 4 (n=4) — 4s² 4p⁶ 4d¹⁰ 4f¹⁴ 32 / 32 electrons (100%)

Shell 5 (n=5) — 5s² 5p⁶ 8 / 50 electrons (16%)

Shell 6 (n=6) — 6s² 2 / 72 electrons (3%)

The 5d⁶ and 6s² electrons are the valence electrons. The 4f¹⁴ subshell filled during the lanthanide series (Z=57–71) and sits inside the [Xe] core for osmium.

Quantum Numbers — Valence Electrons (last 8, electrons 69–76)

Electron #	n	l	mₗ	mₛ	Subshell	Notes
69	5	2	-2	+½	5d	Orbital mₗ=−2, first electron (spin up)
70	5	2	-2	−½	5d	Orbital mₗ=−2, second electron (paired)
71	5	2	-1	+½	5d	Orbital mₗ=−1, first electron (spin up)
72	5	2	-1	−½	5d	Orbital mₗ=−1, second electron (paired)
73	5	2	0	+½	5d	Orbital mₗ=0, first electron (spin up)
74	5	2	0	−½	5d	Orbital mₗ=0, second electron (paired)
75	6	0	0	+½	6s	First 6s electron (spin up)
76	6	0	0	−½	6s	Last electron of osmium (spin down)

n = principal quantum number; l = azimuthal (l=2 → d orbital, l=0 → s orbital); mₗ = magnetic quantum number (orientation); mₛ = spin (+½ up, −½ down). Electrons 1–68 fill the [Xe] core + 4f¹⁴.

Last Electron (Electron 76)

n (principal)

l (s-type)

mₗ (magnetic)

−½

mₛ (spin down)

The 76th electron completes the 6s subshell as a spin-down partner to electron 75. Together they form the paired 6s² ground state.

Summary

Interactive reference for osmium's electron configuration ([Xe] 4f¹⁴ 5d⁶ 6s²), orbital diagram, quantum numbers, and key atomic properties.

How it works

The Aufbau principle fills orbitals from lowest to highest energy.
Osmium's 76 electrons fill all subshells from 1s through 6s, including the complete 4f¹⁴ shell.
The condensed (noble-gas) notation replaces the [Xe] core (54 electrons) with the symbol [Xe] in brackets.
The valence region beyond [Xe] is 4f¹⁴ 5d⁶ 6s²: six d electrons and two s electrons.
Six electrons in 5d fill three orbitals doubly and leave two with single electrons, consistent with Hund's rule being overridden by pairing energy.
Use the tabs to explore the subshell table, orbital box diagram, and element facts.

Use cases

Quick reference for chemistry homework on Period 6 transition metals.
Understand why osmium has the highest density of all elements (22.59 g/cm³).
Study the 5d-block orbital filling sequence from hafnium through mercury.
Compare osmium to its neighbor ruthenium (Z=44), which has the same d⁶ s¹ or d⁷ configuration subtlety.
Prepare for exams covering electronic structure of heavy transition metals.
Verify quantum numbers for osmium's outermost electrons.
Teaching aid for atomic structure, oxidation states, and 5d-metal bonding.

Frequently Asked Questions

Last updated: 2026-07-23 · Reviewed by Nham Vu