General | States | Energies | Oxidation & Electrons |Appearance & Characteristics
Reactions | Other Forms |Radius | Conductivity | Abundance
Encyclopedia Britannica articles


Name Cobalt Symbol Co
atomic number 27 Atomic weight 58.9332
Density @ 293 K 8.90 g/cm3 Atomic volume 6.7 cm3/mol
Group Trans. Met. discovered 1737


state (s, l, g) s
melting point 1768.2 K boiling point 3373 K
Heat of fusion 16.190 kJ/mol Heat of vaporization 376.50 kJ/mol
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1st ionization energy 758.4 kJ/mole electronegativity 1.88
2nd ionization energy 1646 kJ/mole electron affinity 63.8 kJ/mole
3rd ionization energy 3232.2 kJ/mole Specific heat 0.42 J/gK
heat atomization 425 kJ/mole atoms

Oxidation & Electrons

Shells 2,8,15,2 electron configuration [Ar] 3d7 4s2
minimum oxidation number -1 maximum oxidation number 5
min. common oxidation no. 0 max. common oxidation no. 3
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Appearance & Characteristics

structure hcp: hexagonal close pkd color bluish-white
uses magnets, Co glass (blue) toxicity
hardness mohs characteristics hard


reaction with air mild, w/ht = Co3O4 reaction with 6M HCl mild, = H2, CoCl2
reaction with 6M HCl mild, = H2, CoCl2 reaction with 15M HNO3 vigorous, = Co(NO3)2, NOx
reaction with 6M NaOH
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Other Forms

number of isotopes 1 hydride(s) none
oxide(s) CoO Co3O4 chloride(s) CoCl2


ionic radius (2- ion) pm ionic radius (1- ion) pm
atomic radius 125 pm ionic radius (1+ ion) pm
ionic radius (2+ ion) 83.8 pm ionic radius (3+ ion) 71.8 pm
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thermal conductivity 100 J/m-sec-deg electrical conductivity 160.256 1/mohm-cm
polarizability 7.5 A^3


source Co sulfides & arsenides rel. abund. solar system 3.352 log
abundance earth's crust 1.4 log cost, pure 21 $/100g
cost, bulk $/100g
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World Wide Web presentation of Chemicool Periodic Table is © Copyright 1996-99 by David D. Hsu. Some data were provided by and used with the permission of JCE Software and is owned and copyright by the Division of Chemical Education, Inc. Additional data were provided by Perkin-Elmer through Peter Lykos of IIT. The information may not be redistributed without the permission of David Hsu or JCE Software.