Technical data for Cesium

Overview Name Cesium Symbol Cs Atomic Number 55 Atomic Weight 132.90545 Density 1.879 g/cc Melting Point 28.44°C Boiling Point 671.°C Thermal properties Phase Solid Melting Point 28.44°C Boiling Point 671.°C Absolute Melting Point 301.59K Absolute Boiling Point 944.K Critical Pressure 9.4MPa (92.77Atm) Critical Temperature 1938.K Heat of Fusion 2.09KJ/mol Heat of Vaporization 65.KJ/mol Heat of Combustion N/A Specific Heat 242.J/(Kg K)[note] Adiabatic Index N/A Neel Point N/A Thermal Conductivity 36.W/(m K) Thermal Expansion N/A Bulk physical properties Density 1.879 g/cc Density (Liquid) 1.843 g/cc Molar Volume 0.000070732 Brinell Hardness 0.14MPa Mohs Hardness 0.2MPa Vickers Hardness N/A Bulk Modulus 1.6GPa Shear Modulus N/A Young Modulus 1.7GPa Poisson Ratio N/A Refractive Index N/A Speed of Sound N/A Thermal Conductivity 36.W/(m K) Thermal Expansion N/A Reactivity Valence 1 Electronegativity 0.79 ElectronAffinity 45.5KJ/mol Ionization Energies 375.7, 2234.3, 3.4×103 KJ/mol Health and Safety Autoignition Point N/A Flashpoint N/A Heat of Combustion N/A DOT Hazard Class 4.3 DOT Numbers 1407 EU Number EU231-155-4 NFPA Fire Rating N/A NFPA Hazards Water Reactive NFPA Health Rating N/A NFPA Reactivity Rating N/A RTECS Classes Other RTECS Number RTECSFK9225000 NFPA Label

Classifications Alternate Names Caesium Names of Allotropes None Block s Group 1 Period 6 Electron Configuration [Xe]6s1 Color Silver Discovery 1860 in Germany Gas phase N/A CAS Number CAS7440-46-2 CID Number CID5354618 Gmelin Number Gmelin15188 NSC Number N/A RTECS Number RTECSFK9225000 Electrical properties Electrical Type Conductor Electrical Conductivity 5.×106S/m Resistivity 2.×10-7m Ω Superconducting Point N/A Magnetic properties Magnetic Type N/A Curie Point N/A Mass Magnetic Susceptibility -2.8×10-9 Molar Magnetic Susceptibility -3.72×10-10 Volume Magnetic Susceptibility -5.26×10-6 Abundances % in Universe 8.×10-8% % in Sun 8.×10-7% % in Meteorites 0.000014% % in Earth's Crust 0.00019% % in Oceans 5.×10-8% % in Humans 2.×10-6% Atomic dimensions and structure Atomic Radius 298.pm Covalent Radius 225.pm Van der Waals Radius N/A Crystal Structure Body Centered Cubic Lattice Angles π/2, π/2, π/2 Lattice Constants 614.1, 614.1, 614.1 pm Space Group Name Im_ 3m Space Group Number 229 Nuclear Properties Half-Life Stable Lifetime Stable Decay Mode N/A Quantum Numbers 2S1/2 Neutron Cross Section 29. Neutron Mass Absorption 0.0077 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 133Cs 100.%