What is the electron configuration of platinum?

The ground-state electron configuration of platinum (Pt, Z=78) is [Xe] 4f¹⁴ 5d⁹ 6s¹. Written in full: 1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁶ 4d¹⁰ 4f¹⁴ 5s² 5p⁶ 5d⁹ 6s¹.

Why is platinum's configuration anomalous?

A strict Aufbau fill predicts [Xe] 4f¹⁴ 5d⁸ 6s², but relativistic effects contract the 6s orbital, lowering its energy and making it nearly degenerate with 5d. The resulting d⁹s¹ arrangement is slightly more stable, so platinum adopts the anomalous configuration.

How many valence electrons does platinum have?

Platinum has 10 valence electrons (the 5d⁹ and 6s¹ electrons), although its chemistry is dominated by the 5d and 6s shells. It most commonly forms +2 and +4 oxidation states.

What noble gas is used in platinum's shorthand notation?

Xenon (Xe, Z=54) is used. [Xe] represents the 54-electron core: 1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁶ 4d¹⁰ 4f¹⁴ 5s² 5p⁶ — wait, Xe does not include 4f. The [Xe] core is 1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁶ 4d¹⁰ 5s² 5p⁶, giving 54 electrons; the remaining 24 electrons (4f¹⁴ 5d⁹ 6s¹) are written explicitly.

What block and period is platinum in?

Platinum is in Period 6, Group 10, and belongs to the d-block (transition metals) of the periodic table.

What are platinum's common oxidation states?

Platinum most commonly exhibits +2 (Pt²⁺, square-planar complexes) and +4 (Pt⁴⁺, octahedral complexes) oxidation states. The 0 oxidation state appears in some organometallic and catalytic complexes.

How does platinum's configuration relate to its catalytic properties?

The partially filled 5d⁹ subshell and the single 6s electron leave accessible d-orbital vacancies that can bind adsorbates. This makes platinum an outstanding heterogeneous catalyst — including in automotive catalytic converters and fuel cells.

Platinum Electron Configuration

Name: Platinum Electron Configuration
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Full electron configuration of platinum (Pt, Z=78): [Xe] 4f¹⁴ 5d⁹ 6s¹, anomalous due to near-degenerate 5d/6s orbitals, with an interactive orbital diagram and quantum-number breakdown.

Z = 78 Pt Platinum

Platinum — Electron Configuration

Atomic number 78 · Transition metal · Period 6, Group 10 · d-block

[Xe] 4f¹⁴ 5d⁹ 6s¹ Anomalous 78 electrons d⁹s¹ (not d⁸s²)

Anomalous Configuration

Aufbau predicts [Xe] 4f¹⁴ 5d⁸ 6s², but platinum's actual ground state is 5d⁹ 6s¹. Relativistic contraction of the 6s orbital lowers its energy until it is nearly degenerate with 5d, making the d⁹s¹ arrangement marginally more stable.

Subshell Breakdown

Subshell	Type	Electrons	Max	Notation
1s	s orbital, shell n=1	2	2	1s²
2s	s orbital, shell n=2	2	2	2s²
2p	p orbitals, shell n=2	6	6	2p⁶
3s	s orbital, shell n=3	2	2	3s²
3p	p orbitals, shell n=3	6	6	3p⁶
3d	d orbitals, shell n=3	10	10	3d¹⁰
4s	s orbital, shell n=4	2	2	4s²
4p	p orbitals, shell n=4	6	6	4p⁶
4d	d orbitals, shell n=4	10	10	4d¹⁰
4f	f orbitals, shell n=4	14	14	4f¹⁴
5s	s orbital, shell n=5	2	2	5s²
5p	p orbitals, shell n=5	6	6	5p⁶
5d	d orbitals, shell n=5	9	10	5d⁹
6s	s orbital, shell n=6	1	2	6s¹
Total		78

Noble-Gas Shorthand

[Xe] 4f¹⁴ 5d⁹ 6s¹

[Xe] = 54-electron xenon core (1s²…5p⁶).

Aufbau Prediction (incorrect)

[Xe] 4f¹⁴ 5d⁸ 6s²

Relativistic effects make 5d⁹ 6s¹ the actual ground state.

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 5d⁹ 17 / 50 electrons (34%)

Shell 6 (n=6) — 6s¹ 1 / 72 electrons (1%)

Shell 5 can hold up to 50 electrons (5s + 5p + 5d + 5f + 5g). Platinum uses 17 of those slots. Shell 6 holds only the anomalous single 6s¹ electron.

Orbital Box Diagram — Valence Region

Only the outermost (valence-relevant) subshells are shown in box form. The [Xe] 4f¹⁴ core is represented compactly below.

[Xe] 54 electrons in filled core (1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁶ 4d¹⁰ 5s² 5p⁶)

4f¹⁴ 7 fully paired f orbitals (14 electrons) — part of the inner core for valence chemistry

9 electrons: 4 orbitals fully paired + 1 singly occupied

1 electron (anomalous — relativistic stabilization moves one electron from 5d to 6s)

Each box is one orbital. Opposing arrows = paired electrons (+½ and −½ spin). Single arrow = unpaired electron. The five 5d orbitals are: 5d_xy, 5d_xz, 5d_yz, 5d_x²−y², 5d_z². The open orbital in 5d and the singly occupied 6s make platinum highly reactive in catalysis.

Quantum Numbers — Outer Electrons (4f, 5d, 6s)

Electron #	n	l	mₗ	mₛ	Subshell
55	4	3	-3	+½	4f
56	4	3	-3	−½	4f
57	4	3	-2	+½	4f
58	4	3	-2	−½	4f
59	4	3	-1	+½	4f
60	4	3	-1	−½	4f
61	4	3	0	+½	4f
62	4	3	0	−½	4f
63	4	3	1	+½	4f
64	4	3	1	−½	4f
65	4	3	2	+½	4f
66	4	3	2	−½	4f
67	4	3	3	+½	4f
68	4	3	3	−½	4f
69	5	2	-2	+½	5d
70	5	2	-2	−½	5d
71	5	2	-1	+½	5d
72	5	2	-1	−½	5d
73	5	2	0	+½	5d
74	5	2	0	−½	5d
75	5	2	1	+½	5d
76	5	2	1	−½	5d
77	5	2	2	+½	5d
78	6	0	0	+½	6s

Electrons 1–54 occupy the [Xe] core. n = principal; l = azimuthal (l=2 → d, l=3 → f); mₗ = magnetic; mₛ = spin. 5d and 6s rows are highlighted.

Summary

Full electron configuration of platinum (Pt, Z=78): [Xe] 4f¹⁴ 5d⁹ 6s¹, anomalous due to near-degenerate 5d/6s orbitals, with an interactive orbital diagram and quantum-number breakdown.

How it works

The Aufbau principle normally fills subshells in order of increasing energy.
Platinum has 78 electrons; the xenon core ([Xe]) accounts for the first 54.
Beyond [Xe], electrons fill the 4f (14 electrons) and then 5d subshells.
Relativistic contraction of the 6s orbital lowers its energy relative to 5d, making the d⁹s¹ arrangement slightly more stable than d⁸s².
The result is an anomalous configuration: [Xe] 4f¹⁴ 5d⁹ 6s¹ instead of the predicted [Xe] 4f¹⁴ 5d⁸ 6s².
The three tabs let you explore the configuration table, orbital box diagram, and element properties.

Use cases

Look up platinum's exact ground-state electron configuration for chemistry coursework.
Understand why platinum is anomalous (d⁹s¹) compared to the naive Aufbau prediction (d⁸s²).
Visualize the 5d and 6s orbital filling for a Period 6 transition metal.
Compare platinum to neighboring elements like palladium (d¹⁰) and osmium (d⁶s²).
Identify platinum's valence electrons and common oxidation states (+2 and +4).
Teaching aid for relativistic effects in heavy-element electron configurations.
Reference for catalysis courses: platinum's open d shell drives its catalytic activity.

Frequently Asked Questions

Last updated: 2026-07-24 · Reviewed by Nham Vu