Chemicool

Co

27

58.9332
Cobalt
General | States | Energies | Oxidation & Electrons |Appearance & Characteristics
Reactions | Other Forms |Radius | Conductivity | Abundance
Encyclopedia Britannica articles

General
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

States
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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Energies
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

Reactions
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

Radius
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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Conductivity
thermal conductivity 100 J/m-sec-deg electrical conductivity 160.256 1/mohm-cm
polarizability 7.5 A^3

Abundance
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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