Element 27 of Periodic table is Cobalt with atomic number 27, atomic weight 58.9332. Cobalt, symbol Co, has a Simple Hexagonal structure and Gray color. Cobalt is a transition metal element. Know everything about Cobalt Facts, Physical Properties, Chemical Properties, Electronic configuration, Atomic and Crystal Structure.


Cobalt is a chemical element with symbol Co and atomic number 27. Like nickel, cobalt in the Earth"s crust is found only in chemically combined form, save for small deposits found in alloys of natural meteoric iron. The free element, produced by reductive smelting, is a hard, lustrous, silver-gray metal.

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Cobalt Facts

Read key information and facts about element Cobalt

Name Cobalt
Atomic Number 27
Atomic Symbol Co
Atomic Weight 58.9332
Phase Solid
Color Gray
Classification transition metal
Group in Periodic Table 9
Group Name cobalt family
Period in Periodic Table 4
Block in Periodic Table d-block
Electronic Configuration 3d7 4s2
Melting Point 1495 °C
Boiling Point 2927 °C
Electronic Shell Structure <2, 8, 15, 2>
CAS Number CAS7440-48-4

How to Locate Cobalt on Periodic Table

Periodic table is arranged by atomic number, number of protons in the nucleus which is same as number of electrons. The atomic number increases from left to right. Periodic table starts at top left ( Atomic number 1) and ends at bottom right (atomic number 118). Therefore you can directly look for atomic number 27 to find Cobalt on periodic table.

Another way to read periodic table and locate an element is by using group number (column) and period number (row). To locate Cobalt on periodic table look for cross section of group 9 and period 4 in the modern periodic table.

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Table of Contents

Physical Properties
Thermal Properties
Crystal Structure
Atomic & Orbital Properties
Chemical Properties
Health and Safety Parameters and Guidelines
Compare Cobalt with other elements

Cobalt History

The element Cobalt was discovered by Georg Brandt in year 1735 in Sweden . Cobalt derived its name from the German word Kobold, meaning "goblin"

Cobalt Presence: Abundance in Nature and Around Us

The table below shows the abundance of Cobalt in Universe, Sun, Meteorites, Earth"s Crust, Oceans and Human Body.

Ppb by weight (1ppb =10^-7 %)
Abundance in Universe 3e-06
Abundance in Sun 4e-06
Abundance in Meteorites 0.00059
Abundance in Earth"s Crust 3e-05
Abundance in Oceans 8×10-9%
Abundance in Humans 2×10-6%

Crystal Structure of Cobalt

The solid state structure of Cobalt is Simple Hexagonal.

The Crystal structure can be described in terms of its unit Cell. The unit Cells repeats itself in three dimensional space to form the structure.

Unit Cell Parameters

The unit cell is represented in terms of its lattice parameters, which are the lengths of the cell edges Lattice Constants (a, b and c)

a b c
250.71 250.71 406.95 pm

and the angles between them Lattice Angles (alpha, beta and gamma).

alpha beta gamma
π/2 π/2 2 π/3

The positions of the atoms inside the unit cell are described by the set of atomic positions ( xi, yi, zi) measured from a reference lattice point.

The symmetry properties of the crystal are described by the concept of space groups. All possible symmetric arrangements of particles in three-dimensional space are described by the 230 space groups (219 distinct types, or 230 if chiral copies are considered distinct.

Space Group Name P63/mmc
Space Group Number 194
Crystal Structure Simple Hexagonal

Cobalt Atomic and Orbital Properties

Cobalt atoms have 27 electrons and the electronic shell structure is <2, 8, 15, 2> with Atomic Term Symbol (Quantum Numbers) 4F9/2.

Atomic Number 27
Number of Electrons (with no charge) 27
Number of Protons 27
Mass Number 59
Number of Neutrons 32
Shell structure (Electrons per energy level) <2, 8, 15, 2>
Electron Configuration 3d7 4s2
Valence Electrons 3d7 4s2
Oxidation State -3;-1 1;2;3;4;5
Atomic Term Symbol (Quantum Numbers) 4F9/2

Shell Structure of Cobalt - Electrons per energy level


Ground State Electronic Configuration of Cobalt - neutral Cobalt atom

The ground state electronic configuration of Neutral Cobalt atom is 3d7 4s2. The portion of Cobalt configuration that is equivalent to the noble gas of the preceding period, is abbreviated as . For atoms with many electrons, this notation can become lengthy and so an abbreviated notation is used.This is important as it is the Valence electrons 3d7 4s2, electrons in the outermost shell that determine the chemical properties of the element.

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Unabbreviated electronic configuration of neutral Cobalt

Complete ground state electronic configuration for the Cobalt atom, Unabbreviated electronic configuration

1s2 2s2 2p6 3s2 3p6 3d7 4s2

Atomic Structure of Cobalt

Cobalt atomic radius is 152 pm, while it"s covalent radius is 126 pm.

Atomic Radius

152 pm (1.52 Å)

Atomic Volume 6.62170786517 cm3
Covalent Radius 126 pm (1.26 Å)
Van der Waals Radius N/A
Neutron Cross Section 37.2 σa/barns

Atomic Spectrum of Cobalt


Cobalt Chemical Properties: Cobalt Ionization Energies and electron affinity

The electron affinity of Cobalt is 63.7 kJ/mol

Valence 4
Electronegativity 1.88
ElectronAffinity 63.7 kJ/mol

Ionization Energy of Cobalt

Refer to table below for Ionization energies of Cobalt

Ionization energy number Enthalpy - kJ/mol
1 760.4
2 1648
3 3232
4 4950
5 7670
6 9840
7 12440
8 15230
9 17959
10 26570
11 2.94×104
12 3.24×104
13 3.66×104
14 3.97×104
15 4.28×104
16 49396
17 52737
18 134810
19 145170
20 1.547×105
21 1.674×105

Cobalt Physical Properties

Refer to below table for Cobalt Physical Properties

Density 8.9 g/cm3
Molar Volume 6.62170786517 cm3

Elastic Properties

Young Modulus 209 GPa
Shear Modulus 75 GPa
Bulk Modulus 180 GPa
Poisson Ratio 0.31

Hardness of Cobalt - Tests to Measure of Hardness of Element

Mohs Hardness 5 MPa
Vickers Hardness 1043 MPa
Brinell Hardness 700 MPa

Cobalt Electrical Properties

Cobalt is Conductor of electricity. Refer to table below for the Electrical properties of Cobalt

Electrical Conductivity 1.7×107 S/m
Resistivity 6×10-8 m Ω
Superconducting Point N/A

Cobalt Heat and Conduction Properties

Thermal Conductivity 100 W/(m K)
Thermal Expansion 0.000013 K-1

Cobalt Magnetic Properties

Magnetic Type Ferromagnetic
Curie Point 1394 K
Mass Magnetic Susceptibility N/A
Molar Magnetic Susceptibility N/A
Volume Magnetic Susceptibility N/A

Optical Properties of Cobalt

Refractive Index N/A

Acoustic Properties of Cobalt

Speed of Sound 4720 m/s

Cobalt Thermal Properties - Enthalpies and thermodynamics

Refer to table below for Thermal properties of Cobalt

Melting Point 1768 K (1495 °C)
Boiling Point 3.2×103 K (2927 °C)
Critical Temperature N/A
Superconducting Point N/A

Enthalpies of Cobalt

Heat of Fusion 16.2 kJ/mol
Heat of Vaporization 375 kJ/mol
Heat of Combustion N/A

Cobalt Isotopes - Nuclear Properties of Cobalt

Isotopes of rhodium. Naturally occurring Cobalt has 1 stable isotope - 59Co.

Isotope Isotope Mass % Abundance T half Decay Mode
59Co 100% Stable N/A

Regulatory and Health - Health and Safety Parameters and Guidelines

CAS Number CAS7440-48-4
RTECS Number RTECSGF8750000
DOT Hazard Class 4.1
DOT Numbers 3089
EU Number N/A
NFPA Fire Rating N/A
NFPA Hazards N/A
NFPA Health Rating N/A
NFPA Reactivity Rating N/A
Autoignition Point N/A
Flashpoint N/A

Database Search

List of unique identifiers to search the element in various chemical registry databases

Database Identifier number
CAS Number - Chemical Abstracts Service (CAS) CAS7440-48-4
CID Number CID104730
Gmelin Number N/A
NSC Number N/A
RTECS Number RTECSGF8750000

Compare Cobalt with all Group 9 elements

Cobalt vs Rhodium Cobalt vs Iridium Cobalt vs Meitnerium

Compare Cobalt with all transition metal elements

Cobalt vs Scandium Cobalt vs Titanium Cobalt vs Vanadium Cobalt vs Chromium Cobalt vs Manganese Cobalt vs Iron Cobalt vs Nickel Cobalt vs Copper Cobalt vs Zinc Cobalt vs Yttrium Cobalt vs Zirconium Cobalt vs Niobium Cobalt vs Molybdenum Cobalt vs Technetium Cobalt vs Ruthenium Cobalt vs Rhodium Cobalt vs Palladium Cobalt vs Silver Cobalt vs Cadmium Cobalt vs Hafnium Cobalt vs Tantalum Cobalt vs Tungsten Cobalt vs Rhenium Cobalt vs Osmium Cobalt vs Iridium Cobalt vs Platinum Cobalt vs Gold Cobalt vs Mercury Cobalt vs Rutherfordium Cobalt vs Dubnium Cobalt vs Seaborgium Cobalt vs Bohrium Cobalt vs Hassium Cobalt vs Meitnerium Cobalt vs Darmstadtium Cobalt vs Roentgenium Cobalt vs Copernicium