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Technical data for Cesium

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

Overview
NameCesium
SymbolCs
Atomic Number55
Atomic Weight132.90545
Density1.879 g/cm3
Melting Point28.44 °C
Boiling Point671 °C

Thermal properties
PhaseSolid
Melting Point28.44 °C
Boiling Point671 °C
Absolute Melting Point301.59 K
Absolute Boiling Point944 K
Critical Pressure9.4 MPa (92.77 Atm)
Critical Temperature1938 K
Heat of Fusion2.09 kJ/mol
Heat of Vaporization65 kJ/mol
Heat of CombustionN/A
Specific Heat242 J/(kg K)[note]
Adiabatic IndexN/A
Neel PointN/A
Thermal Conductivity36 W/(m K)
Thermal ExpansionN/A

Bulk physical properties
Density1.879 g/cm3
Density (Liquid)1.843 g/cm3
Molar Volume0.000070732
Brinell Hardness0.14 MPa
Mohs Hardness0.2 MPa
Vickers HardnessN/A
Bulk Modulus1.6 GPa
Shear ModulusN/A
Young Modulus1.7 GPa
Poisson RatioN/A
Refractive IndexN/A
Speed of SoundN/A
Thermal Conductivity36 W/(m K)
Thermal ExpansionN/A

Reactivity
Valence1
Electronegativity0.79
ElectronAffinity45.5 kJ/mol
Ionization Energies
375.7, 2234.3, 3.4×103 kJ/mol

Health and Safety
Autoignition PointN/A
FlashpointN/A
Heat of CombustionN/A
DOT Hazard Class4.3
DOT Numbers1407
EU NumberN/A
NFPA Fire RatingN/A
NFPA Hazards
Water Reactive
NFPA Health RatingN/A
NFPA Reactivity RatingN/A
RTECS NumberRTECSFK9225000
NFPA LabelNFPA Label

Classifications
Alternate NamesCaesium
Names of AllotropesNone
Blocks
Group1
Period6
Electron Configuration[Xe]6s1
ColorSilver
Discovery
1860 in Germany
Gas phaseN/A
CAS NumberCAS7440-46-2
CID NumberCID5354618
Gmelin NumberN/A
NSC NumberN/A
RTECS NumberRTECSFK9225000

Electrical properties
Electrical TypeConductor
Electrical Conductivity5×106 S/m
Resistivity2×10-7 m Ω
Superconducting PointN/A

Magnetic properties
Magnetic TypeParamagnetic
Curie PointN/A
Mass Magnetic Susceptibility2.8×10-9
Molar Magnetic Susceptibility3.72×10-10
Volume Magnetic Susceptibility5.26×10-6

Abundances
% in Universe8×10-8%
% in Sun8×10-7%
% in Meteorites0.000014%
% in Earth's Crust0.00019%
% in Oceans5×10-8%
% in Humans2×10-6%

Atomic dimensions and structure
Atomic Radius298 pm
Covalent Radius225 pm
Van der Waals RadiusN/A
Crystal StructureBody Centered Cubic
Lattice Angles
π/2, π/2, π/2
Lattice Constants
614.1, 614.1, 614.1 pm
Space Group NameIm_ 3m
Space Group Number229

Nuclear Properties
Half-LifeStable
LifetimeStable
Decay ModeN/A
Quantum Numbers2S1/2
Neutron Cross Section29
Neutron Mass Absorption0.0077
Known Isotopes
112Cs, 113Cs, 114Cs, 115Cs, 116Cs, 117Cs, 118Cs, 119Cs, 120Cs, 121Cs, 122Cs, 123Cs, 124Cs, 125Cs, 126Cs, 127Cs, 128Cs, 129Cs, 130Cs, 131Cs, 132Cs, 133Cs, 134Cs, 135Cs, 136Cs, 137Cs, 138Cs, 139Cs, 140Cs, 141Cs, 142Cs, 143Cs, 144Cs, 145Cs, 146Cs, 147Cs, 148Cs, 149Cs, 150Cs, 151Cs
Stable Isotopes
133Cs
Isotopic Abundances
133Cs100%


Notes on the properties of Cesium:

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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