Hf 72

Hafnium (Hf)

transition-metal

Period: 6 Group: 4 Block: s

Solid

Standard Atomic Weight

Electron configuration

[Xe] 6s² 4f¹⁴ 5d²

Melting point

2232.85 °C (2506 K)

Boiling point

4602.85 °C (4876 K)

Density

1.330000e+4 kg/m³

Oxidation states

−2, 0, +1, +2, +3, +4

Electronegativity (Pauling)

1.3

Ionization energy (1st)

Discovery year

1911

Atomic radius

155 pm

Details

Name origin From Hafnia, the Latin name of Copenhagen.

Discovery country Denmark

Discoverers Dirk Coster, Georg von Hevesy

Hafnium is a dense, corrosion-resistant transition metal in group 4, chemically close to zirconium. It occurs almost entirely with zirconium minerals and is difficult to separate because the two elements have similar ionic sizes and chemistry. A defining technological feature is its very large thermal-neutron absorption cross section, which contrasts with zirconium's low absorption and makes high-purity separation important for nuclear applications.

Hafnium is a ductile metal with a brilliant silver luster. Its properties are considerably influenced by presence of zirconium impurities. Of all the elements, zirconium and hafnium are two of the most difficult to separate. Although their chemistry is almost identical, the density of zirconium is about half of hafnium. Very pure hafnium has been produced, with zirconium being the major impurity.

Hafnium has been successfully alloyed with iron, titanium, niobium, tantalum, and other metals. Hafnium carbide is the most refractory binary composition known, and the nitride is the most refractory of all known metal nitrides (m.p. 3310C). At 700 degrees C hafnium rapidly absorbs hydrogen to form the composition HfH1.86.

Hafnium is resistant to concentrated alkalis, but at elevated temperatures reacts with oxygen, nitrogen, carbon, boron, sulfur, and silicon. Halogens react directly to form tetrahalides.

The name derives from the Latin hafnia for Copenhagen. An element named celtium was erroneously claimed to have been discovered in 1911 by the French chemist Georges Urbain in rare earth samples, until the Danish physicist Niels Bohr, predicted hafnium's properties using his theory of electronic configuration of the elements. Bohr argued that hafnium would not be a rare earth element, but would be found in zirconium ore. Hafnium was discovered by the Dutch physicist Dirk Coster and the Hungarian physicist George von Hevesy in 1923, while working at Bohr's Institute in Copenhagen.

Hafnium was discovered by Dirk Coster, a Danish chemist, and George Charles de Hevesy, a Hungarian chemist, in 1923. They used a method known as X-ray spectroscopy to study the arrangement of the outer electrons of atoms in samples of zirconium ore. The electron structure of hafnium had been predicted by Niels Bohr and Coster and Hevesy found a pattern that matched. Hafnium is difficult to separate from zirconium and is present in all of its ores. It is obtained with the same methods used to extract zirconium.

From Hafinia, the Latin name for Copenhagen. Many years before its discovery in 1923 (credited to D. Coster and G. von Hevesey), Hafnium was thought to be present in various minerals and concentrations. On the basis of the Bohr theory, the new element was expected to be associated with zirconium.

It was finally identified in zircon from Norway, by means of X-ray spectroscope analysis. It was named in honor of the city in which the discovery was made. Most zirconium minerals contain 1 to 5 percent hafnium.

It was originally separated from zirconium by repeated recrystallization of the double ammonium or potassium fluorides by von Hevesey and Jantzen. Metallic hafnium was first prepared by van Arkel and deBoer by passing the vapor of the tetraiodide over a heated tungsten filament. Almost all hafnium metal now produced is made by reducing the tetrachloride with magnesium or with sodium (Kroll Process).

Read about Hafnium on Wikipedia

Images

Properties

Physical

Atomic radius (empirical) 155 pm

Covalent radius 175 pm

Van der Waals radius 212 pm

Metallic radius 144 pm

Density

Molar volume 0.0136 L/mol

Phase at STP solid

Melting point 2232.85 °C

Boiling point 4602.85 °C

Thermal conductivity 23 W/(m·K)

Specific heat capacity 0.144 J/(g·K)

Molar heat capacity 25.73 J/(mol·K)

Crystal structure hcp

Chemical

Electronegativity (Pauling) 1.3

Electronegativity (Allen) 1.16

Electron affinity

Ionization energy (1st)

Ionization energy (2nd)

Ionization energy (3rd)

Ionization energy (4th)

Ionization energy (5th)

Oxidation states −2, 0, +1, +2, +3, +4

Valence electrons 4

Electron configuration

Electron configuration (semantic)

Thermodynamic

Heat of fusion 0.26667358 eV

Heat of vaporization 5.959476 eV

Heat of sublimation 6.436234 eV

Heat of atomization 6.436234 eV

Atomization enthalpy

Nuclear

Stable isotopes 5

Discovery year 1911

Abundance

Abundance (Earth's crust) 3 mg/kg

Abundance (ocean)

Reactivity

N/A

Crystal Structure

Lattice constant a 320 pm

Electronic Structure

Electrons per shell 2, 8, 18, 32, 10, 2

Identifiers

CAS number 7440-58-6

Term symbol

InChI InChI=1S/Hf

InChI Key VBJZVLUMGGDVMO-UHFFFAOYSA-N

Electron Configuration Measured

Ion charge

Protons 72

Electrons 72

Charge Neutral

Configuration Hf: 4f¹⁴ 5d² 6s²

[Xe] 4f¹⁴ 5d² 6s²

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

Orbital diagram

↑↓

2/2

↑↓

2/2

↑↓

6/6

↑↓

2/2

↑↓

6/6

↑↓

2/2

↑↓

10/10

↑↓

6/6

↑↓

2/2

↑↓

10/10

↑↓

6/6

↑↓

2/2

↑↓

14/14

↑

2/10 2↑

Total electrons: 72 Unpaired: 2

Atomic model

Protons 72

Neutrons 108

Electrons 72

Mass number 180

Stability Stable

Isotopes change neutron count, mass, and stability — not the electron configuration of a neutral atom.

Schematic atomic model, not to scale.

Atomic Fingerprint

Emission / Absorption Spectrum

Emission Visible: 380–750 nm

Isotope Distribution

Mass number	Atomic mass (u)	Natural abundance	Half-life
176 Stable	175.9414076 ± 0.0000022	5.2600%	Stable
178 Stable	177.9437058 ± 0.000002	27.2800%	Stable
179 Stable	178.9458232 ± 0.000002	13.6200%	Stable
180 Stable	179.946557 ± 0.000002	35.0800%	Stable

Measured

Phase / State

Solid 25 °C (298.15 K)

Reason: 2207.8 °C below melting point (2232.85 °C)

Melting point 2232.85 °C

Boiling point 4602.85 °C

Below melting by 2207.8 °C

0 K Current temperature: 25 °C 6000 K

Phase timeline

Schematic, not to scale

Solid

Liquid

Gas

Melting

Boiling

25°C

Solid

Liquid

Gas

Current

Phase transition points

Melting point Literature

2232.85 °C

Boiling point Literature

4602.85 °C

Current phase Calculated
Solid

Transition energies

Heat of fusion Literature

0.26667358 eV

Energy required to melt 1 mol at melting point

Heat of vaporization Literature

5.959476 eV

Energy required to vaporize 1 mol at boiling point

Heat of sublimation Literature

6.436234 eV

Energy required to sublime 1 mol at sublimation point

Density

Reference density Literature

1.330000e+4 kg/m³

At standard conditions

Current density Calculated

1.330000e+4 kg/m³

At standard conditions

Atomic Spectra

Showing 10 of 72 Atomic Spectra. Sorted by ion charge (ascending).

Lines Holdings ?

Ion	Charge	Total lines	Transition probabilities	Level designations
Hf I	0	5341	187	3821
Hf II	+1	218	2	10
Hf III	+2	37	0	0
Hf IV	+3	27	0	0
Hf V	+4	82	0	0

NIST Lines Holdings →

Levels Holdings ?

Ion	Charge	Levels
Hf I	0	333
Hf II	+1	125
Hf III	+2	2
Hf IV	+3	2
Hf V	+4	2
Hf VI	+5	2
Hf VII	+6	2
Hf VIII	+7	2
Hf IX	+8	2
Hf X	+9	2

NIST Levels Holdings →

72 Hf 178.49

Hafnium — Atomic Orbital Visualizer

[Xe]6s24f145d2

Energy levels 2 8 18 32 10 2

Oxidation states -2, 0, +1, +2, +3, +4

HOMO 5d n=5 · l=2 · m=-2

Hafnium — Atomic Orbital Visualizer Preview

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72 Hf 178.49

Hafnium — Crystal Structure Visualizer

Primitive Hexagonal · Pearson hP2

Experimental

Pearson hP2

Coord. № 12

Packing 76.698%

Hafnium — Crystal Structure Visualizer Preview

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Ionic Radii

Charge	Coordination	Spin	Radius
+4	4	N/A	57.99999999999999 pm
+4	6	N/A	71 pm
+4	7	N/A	76 pm
+4	8	N/A	83 pm

Compounds

178.490 u

180.949 u

181.951 u

176.943 u

178.946 u

177.944 u

174.942 u

172.940 u

169.940 u

171.939 u

179.947 u

182.953 u

183.955 u

Hf+4

178.490 u

Hf+4

173.940 u

175.941 u

Isotopes (4)

Mass number	Atomic mass (u)	Natural abundance	Half-life	Decay mode
176 Stable	175.9414076 ± 0.0000022	5.2600% ± 0.0700%	Stable	stable
178 Stable	177.9437058 ± 0.000002	27.2800% ± 0.0700%	Stable	stable
179 Stable	178.9458232 ± 0.000002	13.6200% ± 0.0200%	Stable	stable
180 Stable	179.946557 ± 0.000002	35.0800% ± 0.1600%	Stable	stable

176 Stable

Atomic mass (u) 175.9414076 ± 0.0000022

Natural abundance 5.2600% ± 0.0700%

Half-life Stable

Decay mode

stable

178 Stable

Atomic mass (u) 177.9437058 ± 0.000002

Natural abundance 27.2800% ± 0.0700%

Half-life Stable

Decay mode

stable

179 Stable

Atomic mass (u) 178.9458232 ± 0.000002

Natural abundance 13.6200% ± 0.0200%

Half-life Stable

Decay mode

stable

180 Stable

Atomic mass (u) 179.946557 ± 0.000002

Natural abundance 35.0800% ± 0.1600%

Half-life Stable

Decay mode

stable

Spectral Lines

Showing 50 of 1890 Spectral Lines. Only spectral lines with measured intensity are shown by default.

Wavelength (nm)	Intensity	Ion stage	Type	Transition	Accuracy	Source
417.433998 nm	48000	Hf I	emission	5d2.6s2 a 3F → 5d2.(a 3F).6s.(a 4F).6p z 5D*	Measured	NIST
380.03629 nm	36000	Hf I	emission	5d2.6s2 a 3F → 5d2.(a 3F).6s.(a 4F).6p z 5D*	Measured	NIST
382.072307 nm	34000	Hf I	emission	5d2.6s2 a 3F → 5d2.(a 3F).6s.(a 4F).6p y 3F*	Measured	NIST
723.71003 nm	34000	Hf I	emission	5d2.6s2 a 3F → 5d.6s2.(a 2D).6p z 3D*	Measured	NIST
384.917811 nm	32000	Hf I	emission	5d2.6s2 a 1D → 5d2.(a 3F).6s.(a 2F).6p y 1D*	Measured	NIST
713.1807 nm	32000	Hf I	emission	5d2.6s2 a 3F → 5d.6s2.(a 2D).6p z 3D*	Measured	NIST
389.993003 nm	29000	Hf I	emission	5d2.6s2 a 3F → 5d2.(a 3F).6s.(a 4F).6p z 5D*	Measured	NIST
395.181289 nm	26000	Hf I	emission	5d2.6s2 a 3F → 5d2.(a 3F).6s.(a 4F).6p y 3F*	Measured	NIST
385.830632 nm	25000	Hf I	emission	5d2.6s2 a 3F → 5d2.(a 3F).6s.(a 4F).6p y 3D*	Measured	NIST
724.0873 nm	21000	Hf I	emission	5d2.6s2 a 3F → 5d.6s2.(a 2D).6p z 3D*	Measured	NIST
393.137246 nm	19000	Hf I	emission	5d2.6s2 a 3F → 5d2.(a 3F).6s.(a 4F).6p y 3D*	Measured	NIST
480.049829 nm	17000	Hf I	emission	5d2.6s2 a 1D → 5d.6s2.(a 2D).6p z 1P*	Measured	NIST
397.347912 nm	15000	Hf I	emission	5d2.6s2 a 3F → 5d2.(a 3F).6s.(a 4F).6p z 5D*	Measured	NIST
706.38474 nm	15000	Hf I	emission	5d2.6s2 a 1D → 5d.6s2.(a 2D).6p z 3P*	Measured	NIST
381.177553 nm	14000	Hf I	emission	5d2.6s2 a 3F → 5d2.(a 3F).6s.(a 4F).6p z 3G*	Measured	NIST
555.06011 nm	14000	Hf I	emission	5d2.6s2 a 3F → 5d2.(a 3F).6s.(a 4F).6p z 5G*	Measured	NIST
555.211884 nm	14000	Hf I	emission	5d2.6s2 a 1D → 5d.6s2.(a 2D).6p z 1F*	Measured	NIST
456.593715 nm	13000	Hf I	emission	5d2.6s2 a 1D → 5d2.(a 3P).6s.(a 4P).6p y 5D*	Measured	NIST
435.630591 nm	12000	Hf I	emission	5d2.6s2 a 3F → 5d2.(a 3F).6s.(a 4F).6p z 5D*	Measured	NIST
445.734411 nm	12000	Hf I	emission	5d2.6s2 a 3F → 5d2.(a 3F).6s.(a 4F).6p z 5F*	Measured	NIST
459.87979 nm	12000	Hf I	emission	5d2.6s2 a 3F → 5d2.(a 3F).6s.(a 4F).6p z 5F*	Measured	NIST
462.086529 nm	12000	Hf I	emission	5d2.6s2 a 3F → 5d2.(a 3F).6s.(a 4F).6p z 5F*	Measured	NIST
465.518924 nm	12000	Hf I	emission	5d2.6s2 a 3P → 5d2.(a 3P).6s.(a 4P).6p z 3S*	Measured	NIST
380.044548 nm	11000	Hf I	emission	5d2.6s2 a 1D → 5d2.(a 3P).6s.(a 4P).6p z 5S*	Measured	NIST
429.477692 nm	11000	Hf I	emission	5d2.6s2 a 3F → 5d2.(a 3F).6s.(a 4F).6p z 5D*	Measured	NIST
681.89395 nm	11000	Hf I	emission	5d2.6s2 a 3P → 5d.6s2.(a 2D).6p z 1F*	Measured	NIST
396.799621 nm	10000	Hf I	emission	5d2.6s2 a 3F → 5d2.(a 3F).6s.(a 4F).6p z 5D*	Measured	NIST
406.28356 nm	10000	Hf I	emission	5d.6s2.(a 2D).6p z 1D* → 3512	Measured	NIST
497.525232 nm	10000	Hf I	emission	5d2.6s2 a 3F → 5d2.(a 3F).6s.(a 4F).6p z 5F*	Measured	NIST
454.093108 nm	8400	Hf I	emission	5d2.6s2 a 1D → 5d2.(a 3F).6s.(a 4F).6p y 3F*	Measured	NIST
443.80364 nm	8300	Hf I	emission	5d2.6s2 a 3P → 5d2.(a 3P).6s.(a 4P).6p z 3S*	Measured	NIST
446.117576 nm	8300	Hf I	emission	5d2.6s2 a 1D → 5d2.(a 3P).6s.(a 4P).6p z 3S*	Measured	NIST
459.891547 nm	8300	Hf I	emission	5d2.6s2 a 3F → 5d2.(a 3F).6s.(a 4F).6p z 5D*	Measured	NIST
408.33549 nm	8000	Hf I	emission	5d.6s2.(a 2D).6p z 1D* → 3499	Measured	NIST
571.91718 nm	7300	Hf I	emission	5d2.6s2 a 3P → 5d.6s2.(a 2D).6p z 1P*	Measured	NIST
403.225898 nm	7200	Hf I	emission	5d2.6s2 a 3F → 5d2.(a 3F).6s.(a 4F).6p y 3F*	Measured	NIST
478.27405 nm	7100	Hf I	emission	5d.6s2.(a 2D).6p z 3F* → 6p2.(3P).5d.(2D).6s c 3D	Measured	NIST
383.001314 nm	6700	Hf I	emission	5d3.(b 4F).6s a 5F → 5d2.(b 1D).6s.(b 2D).6p v 3F*	Measured	NIST
504.743848 nm	6500	Hf I	emission	5d2.6s2 a 3P → 5d2.(a 3F).6s.(a 4F).6p y 3D*	Measured	NIST
485.92338 nm	6400	Hf I	emission	5d.6s2.(a 2D).6p z 3F* → 3512	Measured	NIST
386.09058 nm	6300	Hf I	emission	5d2.6s2 a 3P → 5d2.(a 3F).6s.(a 2F).6p y 1F*	Measured	NIST
441.790242 nm	6200	Hf I	emission	5d2.6s2 a 1D → 5d2.(a 3F).6s.(a 4F).6p y 3D*	Measured	NIST
388.935622 nm	5900	Hf I	emission	5d2.6s2 a 1D → 5d2.(a 3P).6s.(a 4P).6p y 5D*	Measured	NIST
469.90048 nm	5900	Hf I	emission	5d2.(a 3F).6s.(a 4F).6p z 5G* → 5d2.(3F).6s.(a 4F).7s b 5F	Measured	NIST
678.92714 nm	5900	Hf I	emission	5d2.6s2 a 3F → 5d2.(a 3F).6s.(a 4F).6p z 5G*	Measured	NIST
433.027751 nm	5800	Hf I	emission	5d2.6s2 a 3F → 5d2.(a 3F).6s.(a 4F).6p y 3F*	Measured	NIST
410.65431 nm	5600	Hf I	emission	5d2.6s2 a 1G → 5d2.(a 3F).6s.(a 2F).6p y 1F*	Measured	NIST
426.34428 nm	5400	Hf I	emission	5d2.6s2 a 3F → 5d2.(a 3F).6s.(a 4F).6p z 5F*	Measured	NIST
477.37157 nm	5400	Hf I	emission	5d2.6s2 a 3P → 5d.6s2.(a 2D).6p z 1P*	Measured	NIST
590.29382 nm	5400	Hf I	emission	5d2.6s2 a 3F → 5d2.(a 3F).6s.(a 4F).6p z 5G*	Measured	NIST

Extended Properties

Covalent Radii (Extended)

Covalent radius (Pyykkö)

Covalent radius (Pyykkö, double)

Covalent radius (Pyykkö, triple)

Van der Waals Radii

Batsanov

Alvarez

UFF

MM3

Atomic & Metallic Radii

Atomic radius (Rahm)

Metallic radius (C12)

Numbering Scales

Mendeleev

Pettifor

Glawe

Electronegativity Scales

Ghosh

Miedema

Gunnarsson–Lundqvist

Robles–Bartolotti

Polarizability & Dispersion

Dipole polarizability

Dipole polarizability (unc.)

C₆ (Gould–Bučko)

Miedema Parameters

Miedema molar volume

Miedema electron density

Phase Transitions & Allotropes

Melting point	2506.15 K
Boiling point	4873.15 K

Oxidation State Categories

+2 extended

−2 extended

0 extended

+1 extended

+4 main

+3 extended

Advanced Reference Data

Screening Constants (14)

n	Orbital	σ
1	s	1.3984
2	p	4.4012
2	s	18.8102
3	d	13.5702
3	p	21.0168
3	s	21.6885
4	d	36.476
4	f	39.7904
4	p	34.0704
4	s	33.0228

Crystal Radii Detail (4)

Charge	CN	r_crystal (pm)	Origin
4	IV	72	from r^3 vs V plots,
4	VI	85	from r^3 vs V plots,
4	VII	90
4	VIII	97

Isotope Decay Modes (46)

Isotope	Mode	Intensity
153	B+	—
154	B+	100%
154	A	0%
155	B+	100%
155	A	—
156	A	100%
156	B+	—
157	A	94%
157	B+	14%
158	B+	55.7%

X‑ray Scattering Factors (514)

Energy (eV)	f₁	f₂
10	—	2.62338
10.1617	—	2.71485
10.3261	—	2.80951
10.4931	—	2.90326
10.6628	—	2.98247
10.8353	—	3.06384
11.0106	—	3.14744
11.1886	—	3.21346
11.3696	—	3.27509
11.5535	—	3.33789

Additional Data

Estimated Crustal Abundance

The estimated element abundance in the earth's crust.

3.0 milligrams per kilogram

References (1)

[5] Hafnium https://education.jlab.org/itselemental/ele072.html

Estimated Oceanic Abundance

The estimated element abundance in the earth's oceans.

7×10-6 milligrams per liter

References (1)

[5] Hafnium https://education.jlab.org/itselemental/ele072.html

References

(9)

1 PubChem

Data deposited in or computed by PubChem

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2 Atomic Mass Data Center (AMDC), International Atomic Energy Agency (IAEA)

The half-life and atomic mass data was provided by the Atomic Mass Data Center at the International Atomic Energy Agency.

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3 IUPAC Commission on Isotopic Abundances and Atomic Weights (CIAAW)

Hafnium

Element data are cited from the Atomic weights of the elements (an IUPAC Technical Report). The IUPAC periodic table of elements can be found at https://iupac.org/what-we-do/periodic-table-of-elements/. Additional information can be found within IUPAC publication doi:10.1515/pac-2015-0703 Copyright © 2020 International Union of Pure and Applied Chemistry.

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4 IUPAC Periodic Table of the Elements and Isotopes (IPTEI)

The information are cited from Pure Appl. Chem. 2018; 90(12): 1833-2092, https://doi.org/10.1515/pac-2015-0703.

Visit source License

License note: Copyright (c) 2020 International Union of Pure and Applied Chemistry. The International Union of Pure and Applied Chemistry (IUPAC) contribution within Pubchem is provided under a CC-BY-NC-ND 4.0 license, unless otherwise stated.

5 Jefferson Lab, U.S. Department of Energy

Hafnium

Thomas Jefferson National Accelerator Facility (Jefferson Lab) is one of 17 national laboratories funded by the U.S. Department of Energy. The lab's primary mission is to conduct basic research of the atom's nucleus using the lab's unique particle accelerator, known as the Continuous Electron Beam Accelerator Facility (CEBAF). For more information visit https://www.jlab.org/

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License note: Please see citation and linking information: https://education.jlab.org/faq/index.html

6 Los Alamos National Laboratory, U.S. Department of Energy

Hafnium

The periodic table at the LANL (Los Alamos National Laboratory) contains basic element information together with the history, source, properties, use, handling and more. The provenance data may be found from the link under the source name.

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7 NIST Physical Measurement Laboratory

Hafnium

The periodic table contains NIST's critically-evaluated data on atomic properties of the elements. The provenance data that include data for atomic spectroscopy, X-ray and gamma ray, radiation dosimetry, nuclear physics, and condensed matter physics may be found from the link under the source name. Ref: https://www.nist.gov/pml/atomic-spectra-database

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8 PubChem Elements

Hafnium

This section provides all form of data related to element Hafnium.

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9 PubChem Elements

Hafnium

The element property data was retrieved from publications.

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Last updated: May 1, 2026

Data verified: May 12, 2026

Content is reviewed against latest scientific data.