Element 72 · Hafnium (Hf)

Hafnium Bohr model: diagram and electrons per shell

The hafnium Bohr model shows a hafnium atom (Hf) as a small nucleus with its electrons circling it in 6 shells: 2 in shell K, 8 in shell L, 18 in shell M, 32 in shell N, 10 in shell O and 2 in shell P. This page has a rotating 3D hafnium Bohr model, a flat diagram, a table of the electrons in each shell and the steps to draw it yourself.

Rotate the hafnium Bohr model in 3D

Drag to orbit, scroll to zoom.

This is a Bohr model of hafnium (Hf), a simplified picture of a single hafnium atom. Its nucleus holds 72 protons, and a neutral hafnium atom has 72 electrons, arranged around it in 6 shells (2 in shell K, 8 in shell L, 18 in shell M, 32 in shell N, 10 in shell O and 2 in shell P).

Hf K · 21s² L · 82s² 2p⁶ M · 183s² 3p⁶ 3d¹⁰ N · 324s² 4p⁶ 4d¹⁰ 4f¹⁴ O · 105s² 5p⁶ 5d² P · 26s²

Hafnium Bohr model diagram

Bohr model diagram of hafnium: a nucleus of 72 protons with 72 electrons on 6 shells, 2 in shell K, 8 in shell L, 18 in shell M, 32 in shell N, 10 in shell O and 2 in shell P, each ring labelled with its shell letter. — The hafnium Bohr model drawn flat: each ring is a shell, labelled with its letter, and every dot is an electron (2 in shell K, 8 in shell L, 18 in shell M, 32 in shell N, 10 in shell O and 2 in shell P).

Hafnium electrons per shell

A neutral hafnium atom has 72 electrons, one for each of its 72 protons. They fill the shells from the nucleus outwards: 2 in shell K, 8 in shell L, 18 in shell M, 32 in shell N, 10 in shell O and 2 in shell P.

Electrons in each shell of the hafnium Bohr model
Shell	Shell number (n)	Electrons	Most it can hold (2n²)	Subshells
K	1	2	2	1s²
L	2	8	8	2s² 2p⁶
M	3	18	18	3s² 3p⁶ 3d¹⁰
N	4	32	32	4s² 4p⁶ 4d¹⁰ 4f¹⁴
O	5	10	50	5s² 5p⁶ 5d²
P	6	2	72	6s²

How the hafnium Bohr model builds up, shell by shell

Watch the hafnium Bohr model come together: the nucleus first, then each shell in turn, from the innermost outwards, with its electrons joining the ring. The legend names every shell and counts its electrons, so you can read off the arrangement (2 in shell K, 8 in shell L, 18 in shell M, 32 in shell N, 10 in shell O and 2 in shell P) as it forms.

Animation of the hafnium Bohr model being built: a nucleus of 72 protons appears first, then each shell grows in around it and takes its electrons, giving 72 electrons on 6 shells (2 in shell K, 8 in shell L, 18 in shell M, 32 in shell N, 10 in shell O and 2 in shell P). — The hafnium Bohr model built up in six seconds: the nucleus first, then each shell with its electrons, ending with 2 in shell K, 8 in shell L, 18 in shell M, 32 in shell N, 10 in shell O and 2 in shell P. Protons are red, neutrons yellow and electrons blue.

How to draw the hafnium Bohr model

Find the atomic number. Hafnium has atomic number 72, so a neutral atom has 72 protons and 72 electrons.
Draw the nucleus. Put a circle in the centre and write Hf in it. The 72 protons sit there with the neutrons.
Draw the shells. Sketch 6 shells as rings around the nucleus. A shell holds at most 2n² electrons: 2 in the first, 8 in the second, 18 in the third and 32 in the fourth.
Place the electrons. Fill from the inside out: 2 in shell K, 8 in shell L, 18 in shell M, 32 in shell N, 10 in shell O and 2 in shell P.
Check the total. 2 + 8 + 18 + 32 + 10 + 2 = 72, the atomic number, so every electron is accounted for.

Atomic data for the hafnium Bohr model

The numbers behind the hafnium Bohr model, grouped by topic. Radii are in picometres (pm) and energies in kilojoules per mole (kJ/mol).

Identity

Symbol: Hf
Atomic number: 72
Atomic mass: 178.492 u
Family: Transition Metals
Position: group 4, period 6
Block: d-block

Electron configuration

Full: 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁶ 5s² 4d¹⁰ 5p⁶ 6s² 4f¹⁴ 5d²
Shorthand: [Xe] 4f¹⁴ 5d² 6s²
Electrons per shell: 2, 8, 18, 32, 10, 2
Outer-shell electrons: 2 in shell P

Ionisation energies

I₁: 658.5
I₂: 1440
I₃: 2250
I₄: 3216

Energy to remove each electron in turn (kJ/mol). A sharp jump means the next electron comes from an inner shell.

Atomic radii

Calculated (pm): 208
Empirical (pm): 155
Covalent (pm): 152

Electronegativity and electron affinity

Electronegativity (Pauling): 1.3
Electron affinity (kJ/mol): 17.18

Oxidation states

Charges the element commonly takes in compounds.

Physical properties, abundance and history of hafnium

Bulk properties of hafnium, how common it is, who discovered it and some of its compounds.

Physical properties

Phase at room conditions: Solid
Appearance: Steel gray
Melting point: 2232.85°C (2506 K)
Boiling point: 4602.85°C (4876 K)
Density: 13.31 g/cm³
Thermal conductivity (W/m·K): 23
Specific heat (J/g·K): 0.144
Molar heat capacity (J/mol·K): 25.73
Heat of fusion (kJ/mol): 25.1
Heat of vaporisation (kJ/mol): 575

Abundance

Earth's crust (mg/kg): 3
Oceans (mg/L): 0

Discovery

Discovered by: Dirk Coster
Year: 1923

Common compounds

Hafnium Hf
Hafnium oxide HfO2
Hafnium tetrachloride Cl4Hf
Hafnium tetrafluoride F4Hf
Hafnium chloride oxide (HfCl2O) Cl2H2HfO-2
Hafnium selenide (HfSe2) HfSe2
Sulfuric acid, hafnium(4+) salt (2:1) HfO8S2
Hafnium dihydride H2Hf-2

Compounds listed in the PubChem database.

Main isotopes of hafnium

Isotopes of hafnium share the same 72 protons but differ in neutrons. Natural isotopes come first, then the longest-lived others.

Main isotopes of hafnium: mass number, abundance, half-life and decay
Mass number	Natural abundance	Half-life	Decay
174	0.16 %	2 Py	α, 2β⁺
176	5.26 %	stable	–
177	18.6 %	stable	–
178	27.28 %	stable	–
179	13.62 %	stable	–
180	35.08 %	stable	–

α = alpha decay, β⁻ = beta-minus, β⁺ = beta-plus, EC = electron capture, SF = spontaneous fission, p / n = proton / neutron emission.

More about hafnium

Hafnium on the periodic table – properties, isotopes, uses and the full hafnium page.
Transition Metals – all transition metal elements and their trends.
Bohr model of every element – the Bohr model of all 118 elements.