Technical data for Hydrogen

Overview Name Hydrogen Symbol H Atomic Number 1 Atomic Weight 1.008 Density 0.0899 g/l[note] Melting Point -259.14 °C Boiling Point -252.87 °C Thermal properties Phase Gas Melting Point -259.14 °C Boiling Point -252.87 °C Absolute Melting Point 14.01 K Absolute Boiling Point 20.28 K Critical Pressure 1.293 MPa (12.76 Atm) Critical Temperature 32.97 K Heat of Fusion 0.558 kJ/mol Heat of Vaporization 0.452 kJ/mol Specific Heat 14300 J/(kg K)[note] Adiabatic Index 7/5 Neel Point N/A Thermal Conductivity 0.1805 W/(m K) Thermal Expansion N/A Bulk physical properties Density 0.0899 g/l[note] Density (Liquid) N/A Molar Volume 0.01121 Brinell Hardness N/A Mohs Hardness N/A Vickers Hardness N/A Bulk Modulus N/A Shear Modulus N/A Young Modulus N/A Poisson Ratio N/A Refractive Index 1.000132 Speed of Sound 1270 m/s Thermal Conductivity 0.1805 W/(m K) Thermal Expansion N/A Reactivity Valence 1 Electronegativity 2.2 ElectronAffinity 72.8 kJ/mol Ionization Energies 1312 kJ/mol Health and Safety DOT Hazard Class 2.1 DOT Numbers 1966 RTECS Number RTECSMW8900000 NFPA Label

Classifications Alternate Names None Names of Allotropes Dihydrogen Block s Group 1 Period 1 Series Nonmetal Electron Configuration 1s1 Color Colorless Discovery 1766 in The United Kingdom Gas phase Diatomic CAS Number CAS1333-74-0 CID Number CID783 RTECS Number RTECSMW8900000 Electrical properties Electrical Type N/A Electrical Conductivity N/A Resistivity N/A Superconducting Point N/A Magnetic properties Magnetic Type Diamagnetic Curie Point N/A Mass Magnetic Susceptibility -2.48×10-8 m3/Kg Molar Magnetic Susceptibility -4.999×10-11 m3/mol Volume Magnetic Susceptibility -2.23×10-9 Abundances % in Universe 75% % in Sun 75% % in Meteorites 2.4% % in Earth's Crust 0.15% % in Oceans 11% % in Humans 10% Atomic dimensions and structure Atomic Radius 53 pm Covalent Radius 31 pm Van der Waals Radius 120 pm Crystal Structure Simple Hexagonal Lattice Angles π/2, π/2, 2 π/3 Lattice Constants 470, 470, 340 pm Space Group Name P63/mmc Space Group Number 194 Nuclear Properties Half-Life Stable Lifetime Stable Decay Mode N/A Quantum Numbers 2S1/2 Neutron Cross Section 0.332 Neutron Mass Absorption 0.011 Known Isotopes 1H, 2H, 3H, 4H, 5H, 6H, 7H Stable Isotopes 1H, 2H Isotopic Abundances 1H 99.9885% 2H 0.0115%