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CALCIUM


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
face-centered cubic

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
Ca2+ + 2e- = Ca(s)- 2.866
CaO + 2H+ + 2e- = Ca(s) + H2O- 1.90
Ca(OH)2(s)+2e- =Ca(s) + 2OH--3.03

 

19Potassium <= 20Calcium =>21Scandium 
 

Posted by Periodni






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