Periodic Table/Cobalt
← FeNi →
27Co58.9332 Da

Cobalt

Transition Metal·Period 4, Group 9·s-block

Light grey transition element. Some meteorites contain small amounts of metallic cobalt. Generally alloyed for use. Mammals require small amounts of cobalt salts. Cobalt-60, an artificially produced radioactive isotope of Cobalt is an important radioactive tracer and cancer-treatment agent. Discovered by G. Brandt in 1737.

Gallery

Fractions from a cobalt, 7 and 4 grams. Original size in cm: 2 x 2

Hi-Res Images ofChemical Elements, CC BY 3.0 <https://creativecommons.org/licenses/by/3.0>, via Wikimedia Commons, source: https://images-of-elements.com/cobalt.php

Bohr model of Cobalt

Physical Propertiesmass · density · phase · crystal

Atomic Mass

58.9332Da

Density

8.8600g/cm³

Phase (STP)

Solid

Melting Point

1768.2K

Boiling Point

3200.2K

Molar Heat

0.4210J/(mol·K)

Crystal Structure

HEX

Lattice Constant

2.510Å

Atomic Radiiatomic · covalent · van der Waals

Atomic (Empirical)

135.00pm

Covalent

111.00pm

Van der Waals

200.00pm

Electronic Propertieselectronegativity · ionization · affinity

Electron Configuration

[Ar] 3d7 4s2

Electron Shells

2, 8, 15, 2

Electronegativity

1.88Pauling

Electron Affinity

0.7kJ/mol

1st Ionization Energy

7.9kJ/mol

Oxidation States

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

Orbital DiagramAufbau · Hund's rule · Pauli exclusion

↑↓
1s2
↑↓
2s2
↑↓
↑↓
↑↓
2p6
↑↓
3s2
↑↓
↑↓
↑↓
3p6
↑↓
↑↓
↑
↑
↑
3d7
↑↓
4s2

Full: 1s2 2s2 2p6 3s2 3p6 3d7 4s2Short: [Ar] 3d7 4s2

Ionization Energies (27 known)

1st7.9 kJ/mol2nd17.1 kJ/mol3rd33.5 kJ/mol4th51.3 kJ/mol5th79.5 kJ/mol6th102.0 kJ/mol7th128.9 kJ/mol8th157.8 kJ/mol9th186.1 kJ/mol10th275.4 kJ/mol11th305.3 kJ/mol12th336.1 kJ/mol13th378.5 kJ/mol14th410.0 kJ/mol15th441.1 kJ/mol16th512.0 kJ/mol17th546.6 kJ/mol18th1397.2 kJ/mol19th1504.5 kJ/mol20th1606.0 kJ/mol21th1724.0 kJ/mol22th1844.0 kJ/mol23th1960.8 kJ/mol24th2119.4 kJ/mol25th2218.9 kJ/mol26th9544.2 kJ/mol27th10012.1 kJ/molSuccessive Ionization Energies

Emission Spectrumvisible range · characteristic spectral lines

412
400
387
482
535
Co emission
380nm750nm
387.3 nm(100%)412.1 nm(60%)399.5 nm(50%)481.5 nm(20%)535.2 nm(15%)

Abundanceby mass

🌍Earth's Crust
25.0 ppm
🌊Ocean
20.0 ppt
✨Universe
3.0 ppm
🧬Human Body
20.0 ppb

Log scale · ppm = parts per million by mass

Biological Role

Essential (trace)

Core of vitamin B₁₂ (cobalamin). Essential for DNA synthesis and red blood cell formation.

Discovery

Discovered By

George Brandt

Named By

—

Year

1739

Nuclear Data

Known Isotopes

32

Stable Isotopes

4

Stable Mass Numbers

47, 48, 49, 59

Natural isotopic abundance (IUPAC recommended values)

Isotopes of Co32 known

NuclideZNMass (AMU)Half-lifeDecayJπAbundance
47Costable272047.011401Stablep7/2-—
48Costable272148.001857Stablep6+—
49Costable272248.989501Stablep7/2-—
59Costable273258.933194Stablestable (1%)7/2-10000.0000%
76Co274975.97245323.0 msβ⁻ (1%), β⁻n, 2n8-—
77Co275076.97647915.0 msβ⁻ (1%), β⁻n, 2n, 3n7/2-—
78Co275177.983553Unknownβ⁻——

Click any isotope for its full page with decay chain:

47Co48Co49Co50Co51Co52Co53Co54Co55Co56Co57Co58Co59Co60Co61Co62Co63Co64Co65Co66Co67Co68Co69Co70Co71Co72Co73Co74Co75Co76Co77Co78Co
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