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Ne
10
Na
11
Mg
12
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18
K
19
Ca
20
Kr
36
Rb
37
Sr
38

 

Periodic table

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Kalium

en  English

Potassium

fr  French

Potassium

hr  Croatian

Kalij

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Potassio

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Potasio

 

K
K
Kalium

PERIODIC TABLE OF THE ELEMENTS

POTASSIUM

ALKALI METAL

 

Atomic number:19

Group numbers:1

Period:4

Electronic configuration:[Ar] 4s1

Formal oxidation number:+1

Electronegativities:0.82

Atomic radius / pm:227.2

Relative atomic mass:39.0983 ± 0.0001

 

Potassium was discovered by Sir Humphry Davy (GB) in 1807. The origin of the name comes from the Arabic word qali meaning alkali (the origin of the symbol K comes from the Latin word kalium). It is a soft, waxy, silver-white metal. Fresh surfaces have a silvery sheen. Potassium quickly forms dull oxide coating on exposure to air. It reacts strongly with water and gives off a flammable gas. It also reacts violently with oxidants. Potasium occurs only in compounds. Potassium is found in minerals like carnallite [(KMgCl3).6H2O] and sylvite (KCl). Pure metal is produced by the reaction of hot potassium chloride and sodium vapours in a special retort. Pottasium is used as potash in making glass and soap and as saltpetre, potassium nitrate (KNO3) to make explosives and to colour fireworks in mauve. Potassium ions are vital to function of nerve and muscle tissues.

PHYSICAL PROPERTIES

Density / g dm-3:862 (293 K)

 828 (m.p.)

Molar volume / cm3mol-1:45.36 (293 K)

 47.22 (m.p.)

Electrical resistivity / μΩcm:6.15 (20 °C)

THERMAL PROPERTIES

Thermal conductivity / W m-1K-1:102

Melting point / °C:63.28

Boiling point / °C:759

Heat of fusion / kJ mol-1:2.4

Heat of vaporization / kJ mol-1:79.1

Heat of atomization / kJ mol-1:90.14

IONIZATION ENERGIES

First ionization energy / kJ mol-1:418.81

Second ionization energy / kJ mol-1:3051.85

Third ionization energy / kJ mol-1:4419.64

ABUNDANCE OF ELEMENTS

in the atmosphere / ppm:-

in the Earth's crust / ppm:9100

in the oceans / ppm:380

CRYSTALLOGRAPHIC DATA

body-centered cubic

Crystal structure:

body-centered cubic

Unit-cell dimensions / pm:

a=533.4

Space group:

Im3m

ISOTOPES

IsotopeRelative atomic massMass percent (%)
39K38.9637068(3)93.2581(44)
40K39.9639987(3)0.0117(1)
41K40.9618260(3)6.7302(44)

REDUCTION POTENTIALS

Balanced half-reaction Eo / V
K+ + e- = K(s)- 2.925

 

18 Argon <=
19 Potassium
=> 20 Calcium