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Technical data for Potassium

Click any property name to see plots of that property for all the elements.

Overview
NamePotassium
SymbolK
Atomic Number19
Atomic Weight39.0983
Density0.856 g/cm3
Melting Point63.38 °C
Boiling Point759 °C

Thermal properties
PhaseSolid
Melting Point63.38 °C
Boiling Point759 °C
Absolute Melting Point336.53 K
Absolute Boiling Point1032 K
Critical Pressure16 MPa (157.9 Atm)[note]
Critical Temperature2223 K[note]
Heat of Fusion2.33 kJ/mol
Heat of Vaporization76.9 kJ/mol
Heat of Combustion-182 J/(kg K)
Specific Heat757 J/(kg K)[note]
Adiabatic IndexN/A
Neel PointN/A
Thermal Conductivity100 W/(m K)
Thermal ExpansionN/A

Bulk physical properties
Density0.856 g/cm3
Density (Liquid)0.828 g/cm3
Molar Volume0.00004568
Brinell Hardness0.363 MPa
Mohs Hardness0.4 MPa
Vickers HardnessN/A
Bulk Modulus3.1 GPa
Shear Modulus1.3 GPa
Young ModulusN/A
Poisson RatioN/A
Refractive IndexN/A
Speed of Sound2×103 m/s
Thermal Conductivity100 W/(m K)
Thermal ExpansionN/A

Reactivity
Valence1
Electronegativity0.82
ElectronAffinity48.4 kJ/mol
Ionization Energies
418.8, 3052, 4420, 5877, 7975, 9590, 11343, 14944, 16963.7, 48610 kJ/mol

Health and Safety
Autoignition Point440 °C
FlashpointN/A
Heat of Combustion-182 J/(kg K)
DOT Hazard Class4.3
DOT Numbers2257
EU NumberN/A
NFPA Fire Rating3
NFPA Hazards
Water Reactive
NFPA Health Rating3
NFPA Reactivity Rating2
RTECS NumberRTECSTS6460000
NFPA LabelNFPA Label

Classifications
Alternate NamesKalium
Names of AllotropesNone
Blocks
Group1
Period4
Electron Configuration[Ar]4s1
ColorSilver
Discovery
1807 in United Kingdom
Gas phaseN/A
CAS NumberCAS7440-09-7
CID NumberCID5462222
Gmelin NumberN/A
NSC NumberN/A
RTECS NumberRTECSTS6460000

Electrical properties
Electrical TypeConductor
Electrical Conductivity1.4×107 S/m
Resistivity7×10-8 m Ω
Superconducting PointN/A

Magnetic properties
Magnetic TypeParamagnetic
Curie PointN/A
Mass Magnetic Susceptibility6.7×10-9
Molar Magnetic Susceptibility2.62×10-10
Volume Magnetic Susceptibility5.74×10-6

Abundances
% in Universe0.0003%
% in Sun0.0004%
% in Meteorites0.07%
% in Earth's Crust1.5%
% in Oceans0.042%
% in Humans0.2%

Atomic dimensions and structure
Atomic Radius243 pm
Covalent Radius196 pm
Van der Waals Radius275 pm
Crystal StructureBody Centered Cubic
Lattice Angles
π/2, π/2, π/2
Lattice Constants
532.8, 532.8, 532.8 pm
Space Group NameIm_ 3m
Space Group Number229

Nuclear Properties
Half-LifeStable
LifetimeStable
Decay ModeN/A
Quantum Numbers2S1/2
Neutron Cross Section2.1
Neutron Mass Absorption0.0018
Known Isotopes
32K, 33K, 34K, 35K, 36K, 37K, 38K, 39K, 40K, 41K, 42K, 43K, 44K, 45K, 46K, 47K, 48K, 49K, 50K, 51K, 52K, 53K, 54K, 55K
Stable Isotopes
39K, 41K
Isotopic Abundances
39K93.2581%
40K0.0117%
41K6.7302%


Notes on the properties of Potassium:

Critical Pressure: Value estimated based on extrapolation.

Critical Temperature: Value estimated based on extrapolation.

Specific Heat: Value given for solid phase.

Up to date, curated data provided by
Mathematica's ElementData function from Wolfram Research, Inc.

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