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


Name Calcium Symbol Ca
atomic number 20 Atomic weight 40.08
Density @ 293 K 1.55 g/cm3 Atomic volume 29.9 cm3/mol
Group Alkali Earth discovered 1808


state (s, l, g) s
melting point 1112.2 K boiling point 1767 K
Heat of fusion 8.540 kJ/mol Heat of vaporization 153.60 kJ/mol
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1st ionization energy 589.8 kJ/mole electronegativity 1
2nd ionization energy 1145.4 kJ/mole electron affinity kJ/mole
3rd ionization energy 4911.8 kJ/mole Specific heat 0.63 J/gK
heat atomization 178 kJ/mole atoms

Oxidation & Electrons

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

structure hcp: hexagonal close pkd color silvery-white
uses lime, cement toxicity
hardness 1.5 mohs characteristics burns brightly


reaction with air vigorous, = CaO, Ca3N2 reaction with 6M HCl vigorous, = H2, CaCl2
reaction with 6M HCl vigorous, = H2, CaCl2 reaction with 15M HNO3 vigorous, = H2, Ca(NO3)2
reaction with 6M NaOH none
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Other Forms

number of isotopes 6 hydride(s) CaH2
oxide(s) CaO chloride(s) CaCl2


ionic radius (2- ion) pm ionic radius (1- ion) pm
atomic radius 197 pm ionic radius (1+ ion) pm
ionic radius (2+ ion) 114 pm ionic radius (3+ ion) pm
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thermal conductivity 201 J/m-sec-deg electrical conductivity 255.754 1/mohm-cm
polarizability 22.8 A^3


source Calcite (oxide) rel. abund. solar system 4.786 log
abundance earth's crust 4.65 log cost, pure 11 $/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.