What is the noble-gas shorthand for hafnium?

[Xe] 4f¹⁴ 5d² 6s². The [Xe] core represents the filled 1s² through 5p⁶ subshells (54 electrons), leaving four valence electrons: two in 5d and two in 6s.

Why does hafnium have a +4 oxidation state?

Hafnium loses all four of its valence electrons — two from 6s and two from 5d — to reach the stable [Xe] 4f¹⁴ noble-gas-like core, forming Hf⁴⁺.

How many valence electrons does hafnium have?

Hafnium has 4 valence electrons: 2 in the 5d subshell and 2 in the 6s subshell.

What block and period is hafnium in?

Hafnium is in Period 6, Group 4 (IVB), and belongs to the d-block of the periodic table. It is the first Group 4 element in Period 6.

Why is hafnium so similar to zirconium?

The lanthanide contraction — caused by the poor shielding of the 4f electrons — compresses hafnium's atomic radius to nearly the same size as zirconium (Z=40). Both elements have the same d² s² valence configuration and very similar ionic radii, making them the most chemically alike pair in the periodic table.

What is the 4f subshell in hafnium?

The 4f subshell in hafnium is completely filled with 14 electrons (4f¹⁴), part of the xenon-like inner core. It does not participate directly in bonding but its presence causes the lanthanide contraction that shapes hafnium's chemistry.

Hafnium Electron Configuration

Name: Hafnium Electron Configuration
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Author: Nham Vu

Interactive reference for hafnium's electron configuration ([Xe] 4f¹⁴ 5d² 6s²), orbital diagram, quantum numbers, and key atomic properties.

Z = 72 Hf Hafnium

Hafnium — Electron Configuration

Atomic number 72 · Transition metal · Period 6, Group 4 · d-block

[Xe] 4f¹⁴ 5d² 6s² 72 electrons 4 valence e⁻ +4 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	2	10	5d²	valence
6s	s, n=6	2	2	6s²	valence
Total		72

Full Configuration

1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁶ 4d¹⁰ 4f¹⁴ 5s² 5p⁶ 5d² 6s²

All 14 subshells written explicitly.

Noble-Gas Shorthand

[Xe] 4f¹⁴ 5d² 6s²

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

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 5d² and 6s² electrons are the valence electrons that participate in bonding. The 4f¹⁴ subshell fills as part of the lanthanide series (Z=57–71) before hafnium.

Orbital Box Diagram — Valence Region

Showing the 4f, 5d, and 6s subshells. The [Xe] core (1s through 5p) contains 54 paired electrons in fully filled orbitals and is omitted for clarity.

[Xe]

54 electrons in fully filled subshells (1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁶ 4d¹⁰ 5s² 5p⁶) — all paired

14 electrons across 7 orbitals — filled (lanthanide series)

empty

2 electrons (unpaired, per Hund's rule) — 3 orbitals empty

2 electrons (paired) — filled

Each box represents one orbital. Opposing arrows indicate paired electrons with spins +½ and −½. The two 5d electrons follow Hund's rule and occupy separate orbitals before pairing.

Quantum Numbers — Valence Electrons (last 4)

Electron #	n	l	mₗ	mₛ	Subshell
69	5	2	-2	+½	5d
70	5	2	-1	+½	5d
71	6	0	0	+½	6s
72	6	0	0	−½	6s

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

Summary

Interactive reference for hafnium's electron configuration ([Xe] 4f¹⁴ 5d² 6s²), orbital diagram, quantum numbers, and key atomic properties.

How it works

The Aufbau principle fills orbitals from lowest to highest energy.
Hafnium's 72 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 5d² 6s²: two d electrons and two s electrons.
Hafnium shows a +4 oxidation state by losing its two 5d and two 6s electrons.
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 the role of the 4f¹⁴ lanthanide contraction in hafnium's properties.
Compare hafnium to its neighbor zirconium (Z=40), which has nearly identical chemistry.
Study d-block orbital filling patterns in the sixth period.
Prepare for exams covering electronic structure of heavy transition metals.
Teaching aid for atomic structure, periodic trends, and lanthanide contraction lessons.
Verify quantum numbers for hafnium's outermost electrons.

Frequently Asked Questions

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