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19
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20
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21
Rb
37
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38
Y
39

 

Periodic table

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Calcium

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Calcium

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Calcium

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Kalcij

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Calcio

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Calcio

 

Ca
Ca
Calcium

PERIODIC TABLE OF THE ELEMENTS

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 Humphry Davy (GB) in 1808. The origin of the name comes from the Latin word calx meaning lime. It is a fairly hard, silvery-white metal. Exposed surfaces form oxides and nitrides. Calcium reacts with water and oxygen. It only occurs in compounds. Calcium is obtained from minerals like chalk, limestone and marble. Pure metal is produced by replacing the calcium in lime (CaCO3) with aluminium in hot, low pressure retorts. Calcium is used by many forms of life to make shells and bones, as a pure metal it has little use, however two of its compounds, lime (CaO) and gypsum (CaSO4), are in great demand by a number of industries.

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 / W m-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

First ionization energy / kJ mol-1:589.83

Second ionization energy / kJ mol-1:1145.46

Third 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

CRYSTALLOGRAPHIC DATA

face-centered cubic

Crystal structure:

face-centered cubic

Unit-cell dimensions / pm:

a=558.84

Space group:

Fm3m

ISOTOPES

IsotopeRelative atomic massMass percent (%)
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

 

19 Potassium <=
20 Calcium
=> 21 Scandium