Zr 40

Zirconium (Zr)

transition-metal

Period: 5 Group: 4 Block: s

Solid

Standard Atomic Weight

Electron configuration

[Kr] 5s² 4d²

Melting point

1854.85 °C (2128 K)

Boiling point

4408.85 °C (4682 K)

Density

6520 kg/m³

Oxidation states

+1, +2, +3, +4

Electronegativity (Pauling)

1.33

Ionization energy (1st)

Discovery year

1789

Atomic radius

155 pm

Details

Name origin From the mineral, zircon.

Discovery country Germany

Discoverers Martin Klaproth

Zirconium is a lustrous transition metal in group 4, chemically close to hafnium and titanium. It occurs mainly in zircon and related heavy minerals, almost always with hafnium as a companion. The metal is valued for its very low thermal-neutron absorption and its stable, adherent oxide film, which give it a central role in nuclear reactor materials and in corrosion-resistant alloys.

Reactor-grade zirconium is essentially free of hafnium. Zircaloy(R) is an important alloy developed specifically for nuclear applications. Zirconium is exceptionally resistant to corrosion by many common acids and alkalis, by sea water, and by other agents. Alloyed with zinc, zirconium becomes magnetic at temperatures below 35°K.

The name derives from the Arabic zargun for "gold-like". It was discovered in zirconia by the German chemist Martin-Heinrich Klaproth in 1789. Zirconium was first isolated by Swedish chemist Jöns Jacob Berzelius in 1824 in an impure state, and finally by the chemists D. Lely, Jr. and L. Hamburger in a pure state in 1914.

Zirconium was discovered by Martin Heinrich Klaproth, a German chemist, while analyzing the composition of the mineral jargon (ZrSiO4) in 1789. Zirconium was isolated by Jöns Jacob Berzelius, a Swedish chemist, in 1824 and finally prepared in a pure form in 1914. Obtaining pure zirconium is very difficult because it is chemically similar to hafnium, an element which is always found mixed with deposits of zirconium. Today, most zirconium is obtained from the minerals zircon (ZrSiO4) and baddeleyite (ZrO2) through a process known as the Kroll Process.

From the Persian zargun, gold like. Zircon, the primary gemstone of zirconium, is also known as jargon, hyacinth, jacinth, or ligure. This mineral, or its variations, is mentioned in biblical writings. The mineral was not known to contain a new element until Klaproth, in 1789, analyzed a jargon from Ceylon and identified the new element, which Werner named zircon (silex circonius), and which Klaproth called Zirkonertz (zirconia). The impure metal was first isolated by Berzelius in 1824 by heating a mixture of potassium and potassium zirconium fluoride in a small decomposition process they developed.

Read about Zirconium on Wikipedia

Images

Properties

Physical

Atomic radius (empirical) 155 pm

Covalent radius 175 pm

Van der Waals radius 186 pm

Metallic radius 145 pm

Density

Molar volume 0.0141 L/mol

Phase at STP solid

Melting point 1854.85 °C

Boiling point 4408.85 °C

Thermal conductivity 22.7 W/(m·K)

Specific heat capacity 0.278 J/(g·K)

Molar heat capacity 25.36 J/(mol·K)

Crystal structure hcp

Chemical

Electronegativity (Pauling) 1.33

Electronegativity (Allen) 1.32

Electron affinity

Ionization energy (1st)

Ionization energy (2nd)

Ionization energy (3rd)

Ionization energy (4th)

Ionization energy (5th)

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

Valence electrons 4

Electron configuration

Electron configuration (semantic)

Thermodynamic

Heat of fusion 0.17515676 eV

Heat of vaporization 5.938747 eV

Heat of sublimation 6.311862 eV

Heat of atomization 6.311862 eV

Atomization enthalpy

Nuclear

Stable isotopes 4

Discovery year 1789

Abundance

Abundance (Earth's crust) 165 mg/kg

Abundance (ocean)

Reactivity

N/A

Crystal Structure

Lattice constant a 323 pm

Electronic Structure

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

Identifiers

CAS number 7440-67-7

Term symbol

InChI InChI=1S/Zr

InChI Key QCWXUUIWCKQGHC-UHFFFAOYSA-N

Electron Configuration Measured

Ion charge

Protons 40

Electrons 40

Charge Neutral

Configuration Zr: 4d² 5s²

[Kr] 4d² 5s²

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

Orbital diagram

↑↓

2/2

↑↓

2/2

↑↓

6/6

↑↓

2/2

↑↓

6/6

↑↓

2/2

↑↓

10/10

↑↓

6/6

↑↓

2/2

↑

2/10 2↑

Total electrons: 40 Unpaired: 2

Atomic model

Protons 40

Neutrons 50

Electrons 40

Mass number 90

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
90 Stable	89.9046977 ± 0.000002	51.4500%	Stable
91 Stable	90.9056396 ± 0.000002	11.2200%	Stable
92 Stable	91.9050347 ± 0.000002	17.1500%	Stable

Measured

Phase / State

Solid 25 °C (298.15 K)

Reason: 1829.8 °C below melting point (1854.85 °C)

Melting point 1854.85 °C

Boiling point 4408.85 °C

Below melting by 1829.8 °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

1854.85 °C

Boiling point Literature

4408.85 °C

Current phase Calculated
Solid

Transition energies

Heat of fusion Literature

0.17515676 eV

Energy required to melt 1 mol at melting point

Heat of vaporization Literature

5.938747 eV

Energy required to vaporize 1 mol at boiling point

Heat of sublimation Literature

6.311862 eV

Energy required to sublime 1 mol at sublimation point

Density

Reference density Literature

6520 kg/m³

At standard conditions

Current density Calculated

6520 kg/m³

At standard conditions

Atomic Spectra

Showing 10 of 40 Atomic Spectra. Sorted by ion charge (ascending).

Lines Holdings ?

Ion	Charge	Total lines	Transition probabilities	Level designations
Zr I	0	459	0	0
Zr II	+1	207	0	0
Zr III	+2	490	490	490
Zr IV	+3	76	0	76
Zr V	+4	104	0	0
Zr VI	+5	427	427	427

NIST Lines Holdings →

Levels Holdings ?

Ion	Charge	Levels
Zr I	0	262
Zr II	+1	136
Zr III	+2	140
Zr IV	+3	35
Zr V	+4	102
Zr VI	+5	97
Zr VII	+6	2
Zr VIII	+7	2
Zr IX	+8	2
Zr X	+9	2

NIST Levels Holdings →

40 Zr 91.224

Zirconium — Atomic Orbital Visualizer

[Kr]5s24d2

Energy levels 2 8 18 10 2

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

HOMO 4d n=4 · l=2 · m=-2

Zirconium — Atomic Orbital Visualizer Preview

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40 Zr 91.224

Zirconium — Crystal Structure Visualizer

Primitive Hexagonal · Pearson hP2

Experimental

Pearson hP2

Coord. № 12

Packing 75.514%

Zirconium — Crystal Structure Visualizer Preview

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Ionic Radii

Charge	Coordination	Spin	Radius
+4	4	N/A	59 pm
+4	5	N/A	66 pm
+4	6	N/A	72 pm
+4	7	N/A	78 pm
+4	8	N/A	84 pm
+4	9	N/A	89 pm

Compounds

91.220 u

Zr+4

91.220 u

88.909 u

94.908 u

92.906 u

87.910 u

96.911 u

85.916 u

89.905 u

Zr+2

91.220 u

Zr+3

91.220 u

Zr+4

88.909 u

Zr+4

93.906 u

Zr+4

89.905 u

90.906 u

91.905 u

95.908 u

Isotopes (3)

Naturally occurring zirconium contains five isotopes. Fifteen other isotopes are known to exist. Zircon, ZrSiO4, the principal ore, is pure ZrO2 in crystalline form having a hafnium content of about 1%. Zirconium also occurs in some 30 other recognized mineral species. Zirconium is produced commercially by reduction of chloride with magnesium (the Kroll Process), and by other methods. It is a grayish-white lustrous metal. When finely divided, the metal may ignite spontaneously in air, especially at elevated temperatures. The solid metal is much more difficult to ignite. The inherent toxicity of zirconium compounds is low. Hafnium is invariably found in zirconium ores, and the separation is difficult.

Mass number	Atomic mass (u)	Natural abundance	Half-life	Decay mode
90 Stable	89.9046977 ± 0.000002	51.4500% ± 0.4000%	Stable	stable
91 Stable	90.9056396 ± 0.000002	11.2200% ± 0.0500%	Stable	stable
92 Stable	91.9050347 ± 0.000002	17.1500% ± 0.0800%	Stable	stable

90 Stable

Atomic mass (u) 89.9046977 ± 0.000002

Natural abundance 51.4500% ± 0.4000%

Half-life Stable

Decay mode

stable

91 Stable

Atomic mass (u) 90.9056396 ± 0.000002

Natural abundance 11.2200% ± 0.0500%

Half-life Stable

Decay mode

stable

92 Stable

Atomic mass (u) 91.9050347 ± 0.000002

Natural abundance 17.1500% ± 0.0800%

Half-life Stable

Decay mode

stable

Spectral Lines

Wavelength (nm)	Intensity	Ion stage	Type	Transition	Accuracy	Source
382.0196 nm	5	Zr III	emission	4d.4f 3G* → 4d.(2D<5/2>).5g 2[7/2]	Measured	NIST
382.4611 nm	250	Zr III	emission	4d.4f 3H* → 4d.(2D<3/2>).5g 2[9/2]	Measured	NIST
382.7722 nm	300	Zr III	emission	4d.4f 3F* → 4d.(2D<3/2>).5g 2[7/2]	Measured	NIST
382.923 nm	600	Zr III	emission	4d.4f 3H* → 4d.(2D<3/2>).5g 2[11/2]	Measured	NIST
383.0087 nm	250	Zr III	emission	4d.4f 1D* → 4d.(2D<5/2>).5g 2[7/2]	Measured	NIST
383.7038 nm	10	Zr III	emission	4d.4f 3G* → 4d.(2D<5/2>).5g 2[9/2]	Measured	NIST
384.2399 nm	270	Zr III	emission	4d.4f 3F* → 4d.(2D<3/2>).5g 2[9/2]	Measured	NIST
390.7626 nm	5	Zr III	emission	4d.4f 3G* → 4d.(2D<5/2>).5g 2[7/2]	Measured	NIST
391.0786 nm	3	Zr III	emission	4d.4f 3G* → 4d.(2D<5/2>).5g 2[13/2]	Measured	NIST
391.6928 nm	100	Zr III	emission	4d.4f 3F* → 4d.(2D<3/2>).5g 2[9/2]	Measured	NIST
392.0624 nm	400	Zr III	emission	4d.4f 3G* → 4d.(2D<5/2>).5g 2[11/2]	Measured	NIST
392.5804 nm	200	Zr III	emission	4d.4f 3G* → 4d.(2D<5/2>).5g 2[9/2]	Measured	NIST
392.694 nm	120	Zr III	emission	4d.4f 3G* → 4d.(2D<5/2>).5g 2[9/2]	Measured	NIST
393.1478 nm	100	Zr III	emission	5s.5p 3P* → 4d.5d 3S	Measured	NIST
396.3178 nm	500	Zr III	emission	4d.4f 3G* → 4d.(2D<5/2>).5g 2[11/2]	Measured	NIST
396.5231 nm	10	Zr III	emission	4d.4f 3G* → 4d.(2D<5/2>).5g 2[11/2]	Measured	NIST
397.1691 nm	200	Zr III	emission	4d.4f 3G* → 4d.(2D<5/2>).5g 2[9/2]	Measured	NIST
397.3984 nm	220	Zr III	emission	4d.4f 1D* → 4d.(2D<3/2>).5g 2[5/2]	Measured	NIST
398.854 nm	10	Zr III	emission	4d.4f 3D* → 4d.(2D<5/2>).5g 2[5/2]	Measured	NIST
401.632 nm	20	Zr III	emission	4d.4f 3G* → 4d.(2D<3/2>).5g 2[7/2]	Measured	NIST
401.6949 nm	35	Zr III	emission	4d.4f 3G* → 4d.(2D<3/2>).5g 2[7/2]	Measured	NIST
401.7561 nm	3	Zr III	emission	4d.4f 1F* → 4d.(2D<5/2>).5g 2[7/2]	Measured	NIST
401.8142 nm	140	Zr III	emission	4d.4f 1F* → 4d.(2D<5/2>).5g 2[7/2]	Measured	NIST
403.2482 nm	400	Zr III	emission	4d.4f 3G* → 4d.(2D<3/2>).5g 2[9/2]	Measured	NIST
403.3591 nm	180	Zr III	emission	4d.4f 3D* → 4d.(2D<5/2>).5g 2[7/2]	Measured	NIST
403.6779 nm	200	Zr III	emission	4d.4f 1F* → 4d.(2D<5/2>).5g 2[9/2]	Measured	NIST
408.0264 nm	5	Zr III	emission	4d.4f 3G* → 4d.(2D<3/2>).5g 2[11/2]	Measured	NIST
408.7114 nm	150	Zr III	emission	4d.4f 3D* → 4d.(2D<5/2>).5g 2[5/2]	Measured	NIST
412.5432 nm	200	Zr III	emission	4d.4f 3G* → 4d.(2D<3/2>).5g 2[11/2]	Measured	NIST
412.6379 nm	400	Zr III	emission	4d.4f 3D* → 4d.(2D<5/2>).5g 2[7/2]	Measured	NIST
413.2087 nm	200	Zr III	emission	4d.4f 3G* → 4d.(2D<3/2>).5g 2[9/2]	Measured	NIST
413.7442 nm	500	Zr IV	emission	4p6.5d 2D → 4p6.6p 2P*	Measured	NIST
414.6654 nm	20	Zr III	emission	4d.4f 3D* → 4d.(2D<5/2>).5g 2[9/2]	Measured	NIST
415.3368 nm	2	Zr III	emission	4d.4f 3P* → 4d.(2D<5/2>).5g 2[3/2]	Measured	NIST
416.0827 nm	250	Zr III	emission	4d.4f 3D* → 4d.(2D<3/2>).5g 2[5/2]	Measured	NIST
416.5293 nm	15	Zr III	emission	4d.4f 3P* → 4d.(2D<5/2>).5g 2[5/2]	Measured	NIST
417.1353 nm	20	Zr III	emission	4d.4f 3P* → 4d.(2D<5/2>).5g 2[3/2]	Measured	NIST
417.2872 nm	300	Zr III	emission	4d.4f 3P* → 4d.(2D<5/2>).5g 2[5/2]	Measured	NIST
419.3504 nm	275	Zr III	emission	4d.4f 3D* → 4d.(2D<3/2>).5g 2[5/2]	Measured	NIST
419.7309 nm	15	Zr III	emission	4d.4f 3P* → 4d.(2D<5/2>).5g 2[3/2]	Measured	NIST
419.8266 nm	3000	Zr IV	emission	4p6.5d 2D → 4p6.6p 2P*	Measured	NIST
420.3546 nm	200	Zr III	emission	4d.4f 3P* → 4d.(2D<5/2>).5g 2[5/2]	Measured	NIST
423.5695 nm	275	Zr III	emission	4d.4f 1F* → 4d.(2D<3/2>).5g 2[7/2]	Measured	NIST
431.7077 nm	2000	Zr IV	emission	4p6.5d 2D → 4p6.6p 2P*	Measured	NIST
434.2686 nm	400	Zr III	emission	4d.4f 1H* → 4d.(2D<5/2>).5g 2[13/2]	Measured	NIST
440.7385 nm	20	Zr III	emission	4d.4f 1H* → 4d.(2D<5/2>).5g 2[11/2]	Measured	NIST
456.1637 nm	50	Zr III	emission	4d.4f 1P* → 4d.(2D<5/2>).5g 2[3/2]	Measured	NIST
456.922 nm	1800	Zr IV	emission	4p6.5g 2G → 4p6.6h 2H*	Measured	NIST
456.927 nm	1800	Zr IV	emission	4p6.5g 2G → 4p6.6h 2H*	Measured	NIST
460.8973 nm	60	Zr III	emission	4d.4f 1H* → 4d.(2D<3/2>).5g 2[11/2]	Measured	NIST
500.71 nm	N/A	ID 803	emission	2p 2P* → 2s 2S	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

Supply Risk & Economics

Production concentration

Relative supply risk

Reserve distribution

Political stability (top producer)

Political stability (top reserve)

Phase Transitions & Allotropes

Melting point	2127.15 K
Boiling point	4679.15 K

Oxidation State Categories

+4 main

+2 extended

+3 extended

+1 extended

Advanced Reference Data

Screening Constants (10)

n	Orbital	σ
1	s	0.841
2	p	4.0072
2	s	10.6262
3	d	14.4331
3	p	16.1545
3	s	15.6385
4	d	26.9284
4	p	26.54
4	s	25.0984
5	s	33.5545

Crystal Radii Detail (6)

Charge	CN	r_crystal (pm)	Origin
4	IV	73	from r^3 vs V plots,
4	V	80	calculated,
4	VI	86	from r^3 vs V plots,
4	VII	92
4	VIII	98
4	IX	103

Isotope Decay Modes (56)

Isotope	Mode	Intensity
77	B+	—
77	B+p	—
77	p	—
78	B+	—
78	B+p	—
79	B+	100%
79	B+p	—
80	B+	100%
81	B+	100%
81	B+p	0.1%

X‑ray Scattering Factors (724)

Energy (eV)	f₁	f₂
1	—	0.18706
1.0149	—	0.19051
1.0299	—	0.19402
1.0452	—	0.1976
1.0608	—	0.20124
1.0765	—	0.20499
1.0925	—	0.20885
1.1087	—	0.21277
1.1252	—	0.21677
1.142	—	0.22085

Additional Data

Estimated Crustal Abundance

The estimated element abundance in the earth's crust.

1.65×102 milligrams per kilogram

References (1)

[5] Zirconium https://education.jlab.org/itselemental/ele040.html

Estimated Oceanic Abundance

The estimated element abundance in the earth's oceans.

3×10-5 milligrams per liter

References (1)

[5] Zirconium https://education.jlab.org/itselemental/ele040.html

Sources

Sources of this element.

Zirconium is produced from the mineral zircon (ZrSiO4). It is found in abundance in S-type stars, and has been identified in the sun and meteorites. Analysis of lunar rock samples obtained during the various Apollo missions to the moon show a surprisingly high zirconium oxide content, compared with terrestrial rocks.

References (1)

[6] Zirconium https://periodic.lanl.gov/40.shtml

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)

Zirconium

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.

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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

Zirconium

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

Zirconium

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

Zirconium

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

Zirconium

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

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9 PubChem Elements

Zirconium

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.