Potassium

Potassium (K)

Soft silvery metallic element belonging to group 1 of the periodic table (alkali metals). Occurs naturally in seawater and a many minerals. Highly reactive, chemically, it resembles sodium in its behavior and compounds. Discovered by Sir Humphry Davy in 1807.
Atomic Number19
Atomic Weight39.0983
Mass Number39
Group1
Period4
Blocks
Protons19 p+
Neutrons20 n0
Electrons19 e-
Kalium.jpg Animated Bohr Model of K (Potassium) Enhanced Bohr Model of K (Potassium) Bohr Model: K (Potassium) Orbital Diagram of K (Potassium)

Properties

Atomic Radius
220 pm
Molar Volume
Covalent Radius
196 pm
Metallic Radius
203 pm
Ionic Radius
137 pm
Crystal Radius
151 pm
Van der Waals Radius
275 pm
Density
0.89 g/cm³
Energy
Proton Affinity
Electron Affinity
0.50147 eV/particle
Ionization Energy
4.34066354 eV/particle
Heat of Vaporization
2.33 kJ/mol
Heat of Fusion
102.5 kJ/mol
Heat of Formation
Electrons
Electron Shells2, 8, 8, 1
Valence Electrons1
Electron Configuration[Ar] 4s1
Oxidation States-1, 1
Electronegativity
0.82
Electrophilicity
0.7633848415985606 eV/particle
Phases
PhaseSolid
Gas Phase
Boiling Point
1,032.15 K
Melting Point
336.65 K
Critical Pressure
16 MPa
Critical Temperature
2,223.15 K
Triple Point
Visual
Color
Silver
Appearancesilvery gray
Refractive Index
Thermodynamic Properties
Thermal Conductivity
Thermal Expansion
Molar Heat Capacity
Specific Heat Capacity
0.757 J/(g⋅K)
Heat Capacity Ratio (Adiabatic Index)
Electrical Properties
TypeConductor
Electrical Conductivity
14 MS/m
Electrical Resistivity
0.00000007000000000002 m Ω
Superconducting Point
Magnetism
Typeparamagnetic
Magnetic Susceptibility (Mass)
0.0000000067 m³/Kg
Magnetic Susceptibility (Molar)
0.000000000262 m³/mol
Magnetic Susceptibility (Volume)
0.00000574
Magnetic Ordering
Curie Point
Neel Point
Structure
Crystal StructureBody Centered Cubic (BCC)
Lattice Constant
5.23 Å
Lattice Anglesπ/2, π/2, π/2
Mechanical Properties
Hardness
0.4 MPa
Bulk Modulus
3.1 GPa
Shear Modulus
1.3 GPa
Young Modulus
Poisson Ratio
Speed of Sound
2,000 m/s
Classification
CategoryAlkali metals, Alkali metals
CAS GroupIA
IUPAC GroupIA
Glawe Number10
Mendeleev Number3
Pettifor Number10
Geochemical Classalkali metal
Goldschmidt Classlitophile
Other
Gas Basicity
Dipole Polarizability
289.7 ± 0.3 a₀
C6 Dispersion Coefficient
3,923 a₀
Allotropes
Neutron Cross Section
2.1
Neutron Mass Absorption
0.0018
Quantum Numbers2S1/2
Space Group229 (Im_3m)

Isotopes of Potassium

Stable Isotopes3
Unstable Isotopes26
Radioactive Isotopes24

31K

AbundanceRadioactive ☢️
Relative Atomic Mass
31.03678 ± 0.000322 Da
Mass Number31
G-Factor
Half Life
Spin3/2
Quadrupole Moment
Discovery Year2019
Parity+

31K Decay Modes
Decay ModeIntensity
3p100%

32K

Abundance
Relative Atomic Mass
32.023607 ± 0.000429 Da
Mass Number32
G-Factor
Half Life
Spin1
Quadrupole Moment
Discovery Year
Parity+

32K Decay Modes
Decay ModeIntensity
p (proton emission)%

33K

Abundance
Relative Atomic Mass
33.008095 ± 0.000215 Da
Mass Number33
G-Factor
Half Life
Spin3/2
Quadrupole Moment
Discovery Year
Parity+

33K Decay Modes
Decay ModeIntensity
p (proton emission)%

34K

Abundance
Relative Atomic Mass
33.99869 ± 0.00021 Da
Mass Number34
G-Factor
Half Life
Spin1
Quadrupole Moment
Discovery Year
Parity+

34K Decay Modes
Decay ModeIntensity
p (proton emission)%

35K

AbundanceRadioactive ☢️
Relative Atomic Mass
34.988005406 ± 0.00000055 Da
Mass Number35
G-Factor
0.26133333333333 ± 0.0046666666666667
Half Life
175.2 ± 1.9 ms
Spin3/2
Quadrupole Moment
Discovery Year1976
Parity+

35K Decay Modes
Decay ModeIntensity
β+ (β+ decay; β+ = ϵ + e+)100%
β+ p (β+-delayed proton emission)0.37%

36K

AbundanceRadioactive ☢️
Relative Atomic Mass
35.981301887 ± 0.000000349 Da
Mass Number36
G-Factor
0.274 ± 0.0005
Half Life
341 ± 3 ms
Spin2
Quadrupole Moment
Discovery Year1967
Parity+

36K Decay Modes
Decay ModeIntensity
β+ (β+ decay; β+ = ϵ + e+)100%
β+ p (β+-delayed proton emission)0.048%
β+α (β+-delayed α emission)0.0034%

37K

AbundanceRadioactive ☢️
Relative Atomic Mass
36.97337589 ± 0.0000001 Da
Mass Number37
G-Factor
0.13547333333333 ± 0.00004
Half Life
1.23651 ± 0.00094 s
Spin3/2
Quadrupole Moment
0.109 ± 0.004
Discovery Year1958
Parity+

37K Decay Modes
Decay ModeIntensity
β+ (β+ decay; β+ = ϵ + e+)100%

38K

AbundanceRadioactive ☢️
Relative Atomic Mass
37.969081114 ± 0.000000209 Da
Mass Number38
G-Factor
0.457 ± 0.002
Half Life
7.651 ± 0.019 m
Spin3
Quadrupole Moment
Discovery Year1937
Parity+

38K Decay Modes
Decay ModeIntensity
β+ (β+ decay; β+ = ϵ + e+)100%

39K

Abundance
93.2581 ± 0.0044
Relative Atomic Mass
38.96370648482 ± 0.00000000489 Da
Mass Number39
G-Factor
0.26098 ± 0.0000053333333333333
Half Life
Spin3/2
Quadrupole Moment
0.0603 ± 0.0006
Discovery Year1921
Parity+

40K

AbundanceRadioactive ☢️
0.0117 ± 0.0001
Relative Atomic Mass
39.963998165 ± 0.00000006 Da
Mass Number40
G-Factor
Half Life
1.248 ± 0.003 Gy
Spin4
Quadrupole Moment
-0.075 ± 0.0008
Discovery Year1935
Parity-

40K Decay Modes
Decay ModeIntensity
β (β decay)89.28%
β+ (β+ decay; β+ = ϵ + e+)10.72%

41K

Abundance
6.7302 ± 0.0044
Relative Atomic Mass
40.96182525611 ± 0.00000000403 Da
Mass Number41
G-Factor
0.143248 ± 0.0000033333333333333
Half Life
Spin3/2
Quadrupole Moment
0.0734 ± 0.0007
Discovery Year1921
Parity+

42K

AbundanceRadioactive ☢️
Relative Atomic Mass
41.962402305 ± 0.000000113 Da
Mass Number42
G-Factor
-0.57125 ± 0.0003
Half Life
12.355 ± 0.007 h
Spin2
Quadrupole Moment
Discovery Year1935
Parity-

42K Decay Modes
Decay ModeIntensity
β (β decay)100%

43K

AbundanceRadioactive ☢️
Relative Atomic Mass
42.960734701 ± 0.00000044 Da
Mass Number43
G-Factor
0.10886666666667 ± 0.00053333333333333
Half Life
22.3 ± 0.1 h
Spin3/2
Quadrupole Moment
Discovery Year1949
Parity+

43K Decay Modes
Decay ModeIntensity
β (β decay)100%

44K

AbundanceRadioactive ☢️
Relative Atomic Mass
43.961586984 ± 0.00000045 Da
Mass Number44
G-Factor
-0.428 ± 0.002
Half Life
22.13 ± 0.19 m
Spin2
Quadrupole Moment
Discovery Year1954
Parity-

44K Decay Modes
Decay ModeIntensity
β (β decay)100%

45K

AbundanceRadioactive ☢️
Relative Atomic Mass
44.960691491 ± 0.00000056 Da
Mass Number45
G-Factor
0.1156 ± 0.00053333333333333
Half Life
17.8 ± 0.6 m
Spin3/2
Quadrupole Moment
Discovery Year1964
Parity+

45K Decay Modes
Decay ModeIntensity
β (β decay)100%

46K

AbundanceRadioactive ☢️
Relative Atomic Mass
45.961981584 ± 0.00000078 Da
Mass Number46
G-Factor
-0.5255 ± 0.003
Half Life
96.3 ± 0.08 s
Spin2
Quadrupole Moment
Discovery Year1965
Parity-

46K Decay Modes
Decay ModeIntensity
β (β decay)100%

47K

AbundanceRadioactive ☢️
Relative Atomic Mass
46.961661612 ± 0.0000015 Da
Mass Number47
G-Factor
3.866 ± 0.018
Half Life
17.38 ± 0.03 s
Spin1/2
Quadrupole Moment
0
Discovery Year1964
Parity+

47K Decay Modes
Decay ModeIntensity
β (β decay)100%

48K

AbundanceRadioactive ☢️
Relative Atomic Mass
47.965341184 ± 0.00000083 Da
Mass Number48
G-Factor
Half Life
6.83 ± 0.14 s
Spin1
Quadrupole Moment
Discovery Year1972
Parity-

48K Decay Modes
Decay ModeIntensity
β (β decay)100%
β n (β-delayed neutron emission)1.14%

49K

AbundanceRadioactive ☢️
Relative Atomic Mass
48.968210753 ± 0.00000086 Da
Mass Number49
G-Factor
2.6772 ± 0.0016
Half Life
1.26 ± 0.05 s
Spin1/2
Quadrupole Moment
0
Discovery Year1972
Parity+

49K Decay Modes
Decay ModeIntensity
β (β decay)100%
β n (β-delayed neutron emission)86%

50K

AbundanceRadioactive ☢️
Relative Atomic Mass
49.972380015 ± 0.0000083 Da
Mass Number50
G-Factor
0
Half Life
472 ± 4 ms
Spin0
Quadrupole Moment
0
Discovery Year1972
Parity-

50K Decay Modes
Decay ModeIntensity
β (β decay)100%
β n (β-delayed neutron emission)28.6%
2n (2-neutron emission)%

51K

AbundanceRadioactive ☢️
Relative Atomic Mass
50.975828664 ± 0.000014 Da
Mass Number51
G-Factor
0.342 ± 0.0013333333333333
Half Life
365 ± 5 ms
Spin3/2
Quadrupole Moment
Discovery Year1983
Parity+

51K Decay Modes
Decay ModeIntensity
β (β decay)100%
β n (β-delayed neutron emission)65%
2n (2-neutron emission)%

52K

AbundanceRadioactive ☢️
Relative Atomic Mass
51.981602 ± 0.000036 Da
Mass Number52
G-Factor
Half Life
110 ± 4 ms
Spin2
Quadrupole Moment
Discovery Year1983
Parity-

52K Decay Modes
Decay ModeIntensity
β (β decay)100%
β n (β-delayed neutron emission)72.2%
2n (2-neutron emission)2.3%

53K

AbundanceRadioactive ☢️
Relative Atomic Mass
52.9868 ± 0.00012 Da
Mass Number53
G-Factor
Half Life
30 ± 5 ms
Spin3/2
Quadrupole Moment
Discovery Year1983
Parity+

53K Decay Modes
Decay ModeIntensity
β (β decay)100%
β n (β-delayed neutron emission)64%
2n (2-neutron emission)10%

54K

AbundanceRadioactive ☢️
Relative Atomic Mass
53.994471 ± 0.000429 Da
Mass Number54
G-Factor
Half Life
10 ± 5 ms
Spin2
Quadrupole Moment
Discovery Year1983
Parity-

54K Decay Modes
Decay ModeIntensity
β (β decay)100%
β n (β-delayed neutron emission)%
2n (2-neutron emission)%

55K

AbundanceRadioactive ☢️
Relative Atomic Mass
55.000505 ± 0.000537 Da
Mass Number55
G-Factor
Half Life
Spin3/2
Quadrupole Moment
Discovery Year2009
Parity+

55K Decay Modes
Decay ModeIntensity
β (β decay)%
β n (β-delayed neutron emission)%
2n (2-neutron emission)%

56K

AbundanceRadioactive ☢️
Relative Atomic Mass
56.008567 ± 0.000644 Da
Mass Number56
G-Factor
Half Life
Spin2
Quadrupole Moment
Discovery Year2009
Parity-

56K Decay Modes
Decay ModeIntensity
β (β decay)%
β n (β-delayed neutron emission)%
2n (2-neutron emission)%

57K

AbundanceRadioactive ☢️
Relative Atomic Mass
57.015169 ± 0.000644 Da
Mass Number57
G-Factor
Half Life
Spin3/2
Quadrupole Moment
Discovery Year2018
Parity+

57K Decay Modes
Decay ModeIntensity
β (β decay)%
β n (β-delayed neutron emission)%
2n (2-neutron emission)%

58K

AbundanceRadioactive ☢️
Relative Atomic Mass
58.023543 ± 0.000751 Da
Mass Number58
G-Factor
Half Life
Spin2
Quadrupole Moment
Discovery Year2019
Parity-

58K Decay Modes
Decay ModeIntensity
β (β decay)%
β n (β-delayed neutron emission)%
2n (2-neutron emission)%

59K

AbundanceRadioactive ☢️
Relative Atomic Mass
59.030864 ± 0.000859 Da
Mass Number59
G-Factor
Half Life
Spin3/2
Quadrupole Moment
Discovery Year2018
Parity+

59K Decay Modes
Decay ModeIntensity
β (β decay)%
β n (β-delayed neutron emission)%
2n (2-neutron emission)%

History

Potassium's symbol K comes from 'kalium' the name of the element in Germany and Scandinavia. Potassium metal was first isolated in 1807 by Sir Humphry Davy, who derived it from caustic potash by the use of electrolysis of the molten salt with the newly discovered voltaic pile. Potassium was the first metal that was isolated by electrolysis. From the English word, potash - pot ashes; Latin kalium, Arab qali, alkali

DiscoverersSir Humphrey Davy
Discovery LocationEngland
Discovery Year1807
Etymology (Name Origin)English: pot ash; symbol from Latin: kalium, (alkali).
Pronunciationpe-TASS-i-em (English)
Potassium must be handled with great care with full skin and eye protection
People whose diets are low in potassium can suffer from hypokalemia

Uses

The greatest demand for potash has been in its use for fertilizers. Potassium is an essential constituent for plant growth and is found in most soils. Potassium nitrate is the main explosive ingredient in gunpowder. Potassium hydroxide is used in the manufacture of soft soaps and as an electrolyte in alkaline batteries. Used as potash in making glass & soap. Also as saltpeter, potassium nitrate (KNO3) to make explosives and to color fireworks in mauve. Formerly called kalium (K). Vital to function of nerve and muscle tissures.

Sources

Found in minerals like carnallite [(KMgCl3).6H2O] & sylvite (potassium chloride, KCL). Pure metal is produced by the reaction of hot potassium chloride and sodium vapors in a special retort.

Abundance
Abundance in Earth's crust
20,900 mg/kg
Abundance in Oceans
399 mg/L
Abundance in Human Body
0.2 %
Abundance in Meteor
0.07 %
Abundance in Sun
0.0004 %
Abundance in Universe
0.0003 %

Nuclear Screening Constants

1s0.5105
2p3.9728
2s5.9938
3p11.2744
3s10.3201
4s15.5048