Chemicool

Cr

24

51.996
Chromium
General | States | Energies | Oxidation & Electrons |Appearance & Characteristics
Reactions | Other Forms |Radius | Conductivity | Abundance
Encyclopedia Britannica articles

General
Name Chromium Symbol Cr
atomic number 24 Atomic weight 51.996
Density @ 293 K 7.19 g/cm3 Atomic volume 7.23 cm3/mol
Group Trans. Met. discovered 1798

States
state (s, l, g) s
melting point 2130.2 K boiling point 2963 K
Heat of fusion 16.90 kJ/mol Heat of vaporization 344.30 kJ/mol
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Energies
1st ionization energy 652.8 kJ/mole electronegativity 1.66
2nd ionization energy 1592 kJ/mole electron affinity 64.3 kJ/mole
3rd ionization energy 2987.2 kJ/mole Specific heat 0.45 J/gK
heat atomization 397 kJ/mole atoms

Oxidation & Electrons
Shells 2,8,13,1 electron configuration [Ar] 3d5 4s1
minimum oxidation number -2 maximum oxidation number 6
min. common oxidation no. 0 max. common oxidation no. 6
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Appearance & Characteristics
structure bcc: body-centered cubic color silvery-white
uses CrO2 tape, paint, steel toxicity
hardness 9 mohs characteristics hard

Reactions
reaction with air none reaction with 6M HCl mild, = H2, CrCl3
reaction with 6M HCl mild, = H2, CrCl3 reaction with 15M HNO3 passivated
reaction with 6M NaOH
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Other Forms
number of isotopes 4 hydride(s) CrH
oxide(s) Cr2O3 CrO2 CrO3+non-stoich chloride(s) CrCl2 CrCl3

Radius
ionic radius (2- ion) pm ionic radius (1- ion) pm
atomic radius 128 pm ionic radius (1+ ion) pm
ionic radius (2+ ion) 90.5 pm ionic radius (3+ ion) 75.5 pm
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Conductivity
thermal conductivity 93.9 J/m-sec-deg electrical conductivity 77.519 1/mohm-cm
polarizability 11.6 A^3

Abundance
source Chromite (oxide) rel. abund. solar system 4.130 log
abundance earth's crust 2 log cost, pure 10 $/100g
cost, bulk $/100g
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