Co 27

Cobalt (Co)

transition-metal

Period: 4 Group: 9 Block: s

Solid

Standard Atomic Weight

Electron configuration

[Ar] 4s² 3d⁷

Melting point

1494.85 °C (1768 K)

Boiling point

2926.85 °C (3200 K)

Density

8860 kg/m³

Oxidation states

−3, −1, 0, +1, +2, +3, +4, +5

Electronegativity (Pauling)

1.88

Ionization energy (1st)

Discovery year

1735

Atomic radius

135 pm

Details

Name origin German: kobold (goblin).

Discovery country Sweden

Discoverers George Brandt

Cobalt is a hard transition metal of group 9, best known for stable high-temperature alloys, magnetic materials, rechargeable battery cathodes, and intensely colored blue pigments. It occurs in nature chiefly as a minor constituent of sulfide and arsenide minerals and is commonly recovered with copper or nickel. Chemically it is dominated by the +2 and +3 oxidation states, with coordination chemistry that includes biologically important corrinoids.

Cobalt is a brittle, hard metal, resembling iron and nickel in appearance. It has a metallic permeability of about two thirds that of iron. Cobalt tends to exist as a mixture of two allotropes over a wide temperature range. The transformation is sluggish and accounts in part for the wide variation in reported data on physical properties of cobalt.

The name derives from the German Kobold for "evil spirits" or "goblins", who were superstitiously thought to cause trouble for miners because the mineral contained arsenic that injured their health and the metallic ores did not yield metals when treated with the normal methods. Cobalt was discovered in 1735 by the Swedish chemist Georg Brandt.

Cobalt was discovered by Georg Brandt, a Swedish chemist, in 1739. Brandt was attempting to prove that the ability of certain minerals to color glass blue was due to an unknown element and not to bismuth, as was commonly believed at the time. Cobalt's primary ores are cobaltite (CoAsS) and erythrite (Co3(AsO4)2). Cobalt is usually recovered as a byproduct of mining and refining nickel, silver, lead, copper and iron.

From the German word Kobald, goblin or evil spirit; also from the Greek cobalos, mine. George Brandt discovered cobalt in 1735.

Read about Cobalt on Wikipedia

Images

Properties

Physical

Atomic radius (empirical) 135 pm

Covalent radius 126 pm

Van der Waals radius 192 pm

Metallic radius 116 pm

Density

Molar volume 0.0067 L/mol

Phase at STP solid

Melting point 1494.85 °C

Boiling point 2926.85 °C

Thermal conductivity 100 W/(m·K)

Specific heat capacity 0.421 J/(g·K)

Molar heat capacity 24.81 J/(mol·K)

Crystal structure hcp

Chemical

Electronegativity (Pauling) 1.88

Electronegativity (Allen) 1.84

Electron affinity

Ionization energy (1st)

Ionization energy (2nd)

Ionization energy (3rd)

Ionization energy (4th)

Ionization energy (5th)

Oxidation states −3, −1, 0, +1, +2, +3, +4, +5

Valence electrons 9

Electron configuration

Electron configuration (semantic)

Thermodynamic

Heat of fusion 0.1677981 eV

Heat of vaporization 3.886614 eV

Heat of sublimation 4.40172 eV

Heat of atomization 4.40172 eV

Atomization enthalpy

Nuclear

Stable isotopes 1

Discovery year 1735

Abundance

Abundance (Earth's crust) 25 mg/kg

Abundance (ocean)

Reactivity

N/A

Crystal Structure

Lattice constant a 251 pm

Electronic Structure

Electrons per shell 2, 8, 15, 2

Identifiers

CAS number 7440-48-4

Term symbol

InChI InChI=1S/Co

InChI Key GUTLYIVDDKVIGB-UHFFFAOYSA-N

Electron Configuration Measured

Ion charge

Protons 27

Electrons 27

Charge Neutral

Configuration Co: 3d⁷ 4s²

[Ar] 3d⁷ 4s²

1s² 2s² 2p⁶ 3s² 3p⁶ 3d⁷ 4s²

Orbital diagram

↑↓

2/2

↑↓

2/2

↑↓

6/6

↑↓

2/2

↑↓

6/6

↑↓

2/2

↑↓

↑

7/10 3↑

Total electrons: 27 Unpaired: 3

Atomic model

Protons 27

Neutrons 32

Electrons 27

Mass number 59

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
59 Stable	58.93319429 ± 0.00000056	100.0000%	Stable

Measured

Phase / State

Solid 25 °C (298.15 K)

Reason: 1469.8 °C below melting point (1494.85 °C)

Melting point 1494.85 °C

Boiling point 2926.85 °C

Below melting by 1469.8 °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

1494.85 °C

Boiling point Literature

2926.85 °C

Current phase Calculated
Solid

Transition energies

Heat of fusion Literature

0.1677981 eV

Energy required to melt 1 mol at melting point

Heat of vaporization Literature

3.886614 eV

Energy required to vaporize 1 mol at boiling point

Heat of sublimation Literature

4.40172 eV

Energy required to sublime 1 mol at sublimation point

Density

Reference density Literature

8860 kg/m³

At standard conditions

Current density Calculated

8860 kg/m³

At standard conditions

Atomic Spectra

Showing 10 of 27 Atomic Spectra. Sorted by ion charge (ascending).

Lines Holdings ?

Ion	Charge	Total lines	Transition probabilities	Level designations
Co I	0	420	338	338
Co II	+1	3168	2761	3168
Co III	+2	2064	1957	2064
Co IV	+3	9	0	0
Co V	+4	55	0	0
Co VIII	+7	165	150	165
Co IX	+8	48	19	48
Co X	+9	22	5	22

NIST Lines Holdings →

Levels Holdings ?

Ion	Charge	Levels
Co I	0	330
Co II	+1	482
Co III	+2	288
Co IV	+3	297
Co V	+4	268
Co VI	+5	180
Co VII	+6	65
Co VIII	+7	73
Co IX	+8	40
Co X	+9	31

NIST Levels Holdings →

27 Co 58.933194

Cobalt — Atomic Orbital Visualizer

[Ar]4s23d7

Energy levels 2 8 15 2

Oxidation states -3, -1, 0, +1, +2, +3, +4, +5

HOMO 3d n=3 · l=2 · m=-2

Cobalt — Atomic Orbital Visualizer Preview

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27 Co 58.933194

Cobalt — Crystal Structure Visualizer

Primitive Hexagonal · Pearson hP2

Experimental

Pearson hP2

Coord. № 12

Packing 74.048%

Cobalt — Crystal Structure Visualizer Preview

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Ionic Radii

Charge	Coordination	Spin	Radius
+2	4	high	57.99999999999999 pm
+2	5	N/A	67 pm
+2	6	low	65 pm
+2	6	high	74.5 pm
+2	8	N/A	90 pm
+3	6	low	54.50000000000001 pm
+3	6	high	61 pm
+4	4	N/A	40 pm
+4	6	high	53 pm

Compounds

58.933 u

Co+2

58.933 u

59.934 u

Co+3

58.933 u

57.936 u

56.936 u

54.942 u

55.940 u

Co+2

56.936 u

Co+2

59.934 u

Co+2

57.936 u

61.934 u

60.932 u

58.933 u

Co+3

58.933 u

Isotopes (1)

Cobalt-60, an artificial isotope, is an important gamma ray source, and is extensively used as a tracer and a radiotherapeutic agent.

	Mass number	Atomic mass (u)	Natural abundance	Half-life	Decay mode
	59 Stable	58.93319429 ± 0.00000056	100.0000%	Stable	stable

59 Stable

Atomic mass (u) 58.93319429 ± 0.00000056

Natural abundance 100.0000%

Half-life Stable

Decay mode

stable

Spectral Lines

Showing 50 of 738 Spectral Lines. Only spectral lines with measured intensity are shown by default.

Wavelength (nm)	Intensity	Ion stage	Type	Transition	Accuracy	Source
389.4073 nm	7900	Co I	emission	3p6.3d8.(3F).4s a 2F → 3p6.3d8.(3F).4p y 2G*	Measured	NIST
384.5461 nm	6900	Co I	emission	3p6.3d8.(3F).4s a 2F → 3p6.3d8.(3F).4p y 2G*	Measured	NIST
399.5302 nm	6000	Co I	emission	3p6.3d8.(3F).4s a 2F → 3p6.3d8.(3F).4p y 4G*	Measured	NIST
512.92021 nm	5800	Co II	emission	3d7.(4F).4d e 5H → 3d7.(4F<9/2>).4f 2[15/2]*	Measured	NIST
387.3114 nm	5500	Co I	emission	3p6.3d8.(3F).4s b 4F → 3p6.3d7.(4F).4s.4p.(3P) z 4D	Measured	NIST
412.1311 nm	4400	Co I	emission	3p6.3d8.(3F).4s a 2F → 3p6.3d7.(4F).4s.4p.(3P) z 2G	Measured	NIST
516.315 nm	4100	Co II	emission	3d7.(4F).4d e 3H → 3d7.(4F<7/2>).4f 2[13/2]*	Measured	NIST
521.43464 nm	3900	Co II	emission	3d7.(4F).4d e 5H → 3d7.(4F<9/2>).4f 2[15/2]*	Measured	NIST
505.07089 nm	3800	Co II	emission	3d7.(4F).4d e 5G → 3d7.(4F<9/2>).4f 2[13/2]*	Measured	NIST
517.06829 nm	3200	Co II	emission	3d7.(4F).4d e 5H → 3d7.(4F<7/2>).4f 2[13/2]*	Measured	NIST
387.3955 nm	2800	Co I	emission	3p6.3d8.(3F).4s b 4F → 3p6.3d7.(4F).4s.4p.(3P) z 4D	Measured	NIST
411.8767 nm	2800	Co I	emission	3p6.3d8.(3F).4s a 2F → 3p6.3d7.(4F).4s.4p.(3P) z 2G	Measured	NIST
519.95128 nm	2800	Co II	emission	3d7.(4F).4d e 3H → 3d7.(4F<5/2>).4f 2[11/2]*	Measured	NIST
513.56812 nm	2700	Co II	emission	3d7.(4F).4d e 5H → 3d7.(4F<5/2>).4f 2[11/2]*	Measured	NIST
509.92115 nm	2500	Co II	emission	3d7.(4F).4d e 3G → 3d7.(4F<7/2>).4f 2[11/2]*	Measured	NIST
523.11044 nm	2300	Co II	emission	3d7.(4F).4d e 3H → 3d7.(4F<3/2>).4f 2[9/2]*	Measured	NIST
496.41682 nm	2200	Co II	emission	3d7.(4F).4d f 5F → 3d7.(4F<9/2>).4f 2[11/2]*	Measured	NIST
505.7416 nm	1700	Co II	emission	3d7.(4F).4d e 5G → 3d7.(4F<9/2>).4f 2[11/2]*	Measured	NIST
393.5959 nm	1500	Co I	emission	3p6.3d8.(3F).4s a 2F → 3p6.3d8.(3F).4p y 4F*	Measured	NIST
384.2046 nm	1400	Co I	emission	3p6.3d8.(3F).4s a 2F → 3p6.3d7.(4F).4s.4p.(3P) z 2D	Measured	NIST
509.52694 nm	1400	Co II	emission	3d7.(4F).4d e 3G → 3d7.(4F<5/2>).4f 2[9/2]*	Measured	NIST
510.75362 nm	1400	Co II	emission	3d7.(4F).4d e 5G → 3d7.(4F<7/2>).4f 2[9/2]*	Measured	NIST
506.70997 nm	1200	Co II	emission	3d7.(4F).4d e 5P → 3d7.(4F<9/2>).4f 2[3/2]*	Measured	NIST
396.31 nm	1100	Co II	emission	3d7.(4F).5p 5F* → 3d7.(4F).6d 5G	Measured	NIST
496.23566 nm	1100	Co II	emission	3d7.(4F).4d f 5F → 3d7.(4F<9/2>).4f 2[9/2]*	Measured	NIST
517.6949 nm	1100	Co II	emission	3d7.(4F).4d e 5G → 3d7.(4F<9/2>).4f 2[13/2]*	Measured	NIST
657.13038 nm	1100	Co II	emission	3d7.(4F).5p 5G* → 3d7.(4F).5d 5H	Measured	NIST
657.62238 nm	1100	Co II	emission	3d7.(4F).5p 3G* → 3d7.(4F).5d 3H	Measured	NIST
502.59107 nm	990	Co II	emission	3d7.(4F).4d e 5D → 3d7.(4F<7/2>).4f 2[11/2]*	Measured	NIST
399.79 nm	970	Co I	emission	3p6.3d8.(3F).4s a 2F → 3p6.3d8.(3F).4p *	Measured	NIST
512.9972 nm	960	Co II	emission	3d7.(4F).4d e 3G → 3d7.(4F<3/2>).4f 2[9/2]*	Measured	NIST
743.9418 nm	960	Co II	emission	3d7.(4F).5p 5D* → 3d7.(4F).6s 5F	Measured	NIST
637.37856 nm	920	Co II	emission	3d7.(4F).5p 5F* → 3d7.(4F).5d 5G	Measured	NIST
495.82966 nm	900	Co II	emission	3d7.(4F).4d f 5F → 3d7.(4F<9/2>).4f 2[11/2]*	Measured	NIST
502.25161 nm	900	Co II	emission	3d7.(4F).4d e 3D → 3d7.(4F<3/2>).4f 2[7/2]*	Measured	NIST
642.58717 nm	900	Co II	emission	3d7.(4F).5p 5F* → 3d7.(4F).5d 5F	Measured	NIST
510.45696 nm	890	Co II	emission	3d7.(4F).4d e 5D → 3d7.(4F<5/2>).4f 2[9/2]*	Measured	NIST
502.36685 nm	860	Co II	emission	3d7.(4F).4d f 5F → 3d7.(4F<9/2>).4f 2[9/2]*	Measured	NIST
620.5716 nm	860	Co II	emission	3d7.(4F).5p 5D* → 3d7.(4F).5d 5F	Measured	NIST
409.2384 nm	830	Co I	emission	3p6.3d8.(3F).4s a 2F → 3p6.3d7.(4F).4s.4p.(3P) z 2F	Measured	NIST
508.31892 nm	780	Co II	emission	3d7.(4F).4d e 5D → 3d7.(4F<3/2>).4f 2[5/2]*	Measured	NIST
502.6664 nm	680	Co II	emission	3d7.(4F).4d e 5G → 3d7.(4F<5/2>).4f 2[7/2]*	Measured	NIST
517.75201 nm	680	Co II	emission	3d7.(4F).4d e 3H → 3d7.(4F<7/2>).4f 2[11/2]*	Measured	NIST
662.16287 nm	680	Co II	emission	3d7.(4F).5p 3G* → 3d7.(4F).5d 3H	Measured	NIST
495.25711 nm	670	Co II	emission	3d7.(4F).4d e 5G → 3d7.(4F<5/2>).4f 2[9/2]*	Measured	NIST
500.77152 nm	640	Co II	emission	3d7.(4F).4d f 5F → 3d7.(4F<9/2>).4f 2[5/2]*	Measured	NIST
510.63945 nm	640	Co II	emission	3d7.(4F).4d e 5D → 3d7.(4F<3/2>).4f 2[5/2]*	Measured	NIST
499.59719 nm	600	Co II	emission	3d7.(4F).4d e 5H → 3d7.(4F<7/2>).4f 2[13/2]*	Measured	NIST
509.2051 nm	600	Co II	emission	3d7.(4F).4d e 5D → 3d7.(4F<3/2>).4f 2[3/2]*	Measured	NIST
510.07741 nm	600	Co II	emission	3d7.(4F).4d e 3G → 3d7.(4F<7/2>).4f 2[9/2]*	Measured	NIST

Extended Properties

Covalent Radii (Extended)

Covalent radius (Pyykkö)

Covalent radius (Pyykkö, double)

Covalent radius (Pyykkö, triple)

Covalent radius (Bragg)

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

C₆ (Gould–Bučko)

Chemical Affinity

Proton affinity

Gas basicity

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	1768.15 K
Boiling point	3200.15 K

Oxidation State Categories

+4 extended

+5 extended

+1 extended

−3 extended

+3 main

0 extended

+2 main

−1 extended

Advanced Reference Data

Screening Constants (7)

n	Orbital	σ
1	s	0.6332
2	p	3.9076
2	s	7.595
3	d	15.1446
3	p	13.5654
3	s	12.6777
4	s	21.4236

Crystal Radii Detail (9)

Charge	CN	Spin	r_crystal (pm)	Origin
2	IV	HS	72
2	V		81	calculated,
2	VI	LS	79	from r^3 vs V plots,
2	VI	HS	88.5	from r^3 vs V plots,
2	VIII		104
3	VI	LS	68.5	from r^3 vs V plots,
3	VI	HS	75
4	IV		54
4	VI	HS	67	from r^3 vs V plots,

Isotope Decay Modes (57)

Isotope	Mode	Intensity
47	p	—
48	p	—
49	p	—
50	B+	100%
50	B+p	70.5%
50	2p	—
51	B+	100%
51	B+p	3.8%
52	B+	100%
52	B+p	—

X‑ray Scattering Factors (504)

Energy (eV)	f₁	f₂
10	—	1.42071
10.1617	—	1.45925
10.3261	—	1.49884
10.4931	—	1.53949
10.6628	—	1.58125
10.8353	—	1.62415
11.0106	—	1.6682
11.1886	—	1.71345
11.3696	—	1.75993
11.5535	—	1.80767

Additional Data

Estimated Crustal Abundance

The estimated element abundance in the earth's crust.

2.5×101 milligrams per kilogram

References (1)

[5] Cobalt https://education.jlab.org/itselemental/ele027.html

Estimated Oceanic Abundance

The estimated element abundance in the earth's oceans.

2×10-5 milligrams per liter

References (1)

[5] Cobalt https://education.jlab.org/itselemental/ele027.html

Sources

Sources of this element.

Cobalt occurs in the minerals cobaltite, smaltite, and erythrite, and is often associated with nickel, silver, lead, copper, and iron ores, from which it is most frequently obtained as a by-product. It is also present in meteorites.

Important ore deposits are found in Zaire, Morocco, and Canada. The U.S. Geological Survey has announced that the bottom of the north central Pacific Ocean may have cobalt-rich deposits at relatively shallow depths in water close to the the Hawaiian Islands and other U.S. Pacific territories.

References (1)

[6] Cobalt https://periodic.lanl.gov/27.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)

Cobalt

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

Cobalt

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

Cobalt

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

Cobalt

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

Cobalt

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

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9 PubChem Elements

Cobalt

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.