CALCIUM
ALKALINE EARTH METAL
Atomic number:20
Group numbers:2
Period:4
Electronic configuration:[Ar]4s2
Formal oxidation number:+2
Electronegativities:1
Atomic radius / pm:197.4
Relative atomic mass:40.078 ± 0.004
Calcium was discovered by Sir HumphryDavy(GB)in1808. The origin of the name comes from theLatinwordcalxmeaning lime. It is a fairlyhard,silvery-whitemetal.Exposed surfaces form oxides andnitrides.Calcium reactswithwater and oxygen. It only occurs incompounds.Calcium isobtainedfrom minerals like chalk, limestone andmarble.Pure metalisproduced by replacing the calcium in lime(CaCO3) withaluminiuminhot, low pressure retorts. Calcium is usedby many formsof lifetomake shells and bones, as a pure metal it haslittleuse,howevertwo of its compounds, lime (CaO) and gypsum(CaSO4), areingreatdemand by a number of industries.
CRYSTALLOGRAPHIC DATA
Crystal structure:
face-centered cubic
Unit-cell dimensions / pm:
a=558.84
Space group:
Fm3m
PHYSICAL PROPERTIES
Density / g dm-3:1550(293 K)
1365 (m.p.)
Molar volume / cm3mol-1:25.86 (293 K)
29.36 (m.p.)
Electrical resistivity / μΩcm:3.91(20 °C)
THERMAL PROPERTIES
Thermal conductivity / Wm-1K-1:190
Melting point / °C:842
Boiling point / °C:1484
Heat of fusion / kJ mol-1:9.33
Heat of vaporization / kJ mol-1:150.6
Heat of atomization / kJ mol-1:177.74
IONIZATION ENERGIES
1st ionization energy / kJ mol-1:589.83
2nd ionization energy / kJ mol-1:1145.46
3rd ionization energy / kJ mol-1:4912.40
ABUNDANCE OF ELEMENTS
in the atmosphere / ppm:-
in the Earth's crust / ppm:52900
in the oceans / ppm:400
ISOTOPES
IsotopeRelativeatomicmassMasspercent(%)
40Ca39.9625911(3)96.941(18)
42Ca41.9586183(4)0.647(9)
43Ca42.9587668(5)0.135(6)
44Ca43.9554811(9)2.086(12)
46Ca45.953693(3)0.004(3)
48Ca47.952534(4)0.187(4)
REDUCTION POTENTIALS
Balanced half-reaction Eo / V
Ca
2+ + 2e
- Ca
(s)- 2.866CaO + 2H
+ + 2e
- Ca
(s) + H
2O
- 1.90Ca(OH)
2(s)+2e
- Ca
(s) + 2OH
--3.03
19Potassium <= 20Calcium =>21Scandium
Posted by Periodni
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