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Technical data for Hydrogen

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

Overview
NameHydrogen
SymbolH
Atomic Number1
Atomic Weight1.00794
Density0.0899 g/l[note]
Melting Point-259.14 °C
Boiling Point-252.87 °C

Thermal properties
PhaseGas
Melting Point-259.14 °C
Boiling Point-252.87 °C
Absolute Melting Point14.01 K
Absolute Boiling Point20.28 K
Critical Pressure1.293 MPa (12.76 Atm)
Critical Temperature32.97 K
Heat of Fusion0.558 kJ/mol
Heat of Vaporization0.452 kJ/mol
Heat of CombustionN/A
Specific Heat14300 J/(kg K)[note]
Adiabatic Index7/5
Neel PointN/A
Thermal Conductivity0.1805 W/(m K)
Thermal ExpansionN/A

Bulk physical properties
Density0.0899 g/l[note]
Density (Liquid)N/A
Molar Volume0.01121
Brinell HardnessN/A
Mohs HardnessN/A
Vickers HardnessN/A
Bulk ModulusN/A
Shear ModulusN/A
Young ModulusN/A
Poisson RatioN/A
Refractive Index1.000132
Speed of Sound1270 m/s
Thermal Conductivity0.1805 W/(m K)
Thermal ExpansionN/A

Reactivity
Valence1
Electronegativity2.2
ElectronAffinity72.8 kJ/mol
Ionization Energies
1312 kJ/mol

Health and Safety
Autoignition Point535.5 °C
Flashpoint-18 °C
Heat of CombustionN/A
DOT Hazard Class2.1
DOT Numbers1966
EU NumberN/A
NFPA Fire Rating4
NFPA HazardsN/A
NFPA Health Rating3
NFPA Reactivity Rating0
RTECS NumberRTECSMW8900000
NFPA LabelNFPA Label

Classifications
Alternate NamesNone
Names of AllotropesDihydrogen
Blocks
Group1
Period1
Electron Configuration1s1
ColorColorless
Discovery
1766 in United Kingdom
Gas phaseDiatomic
CAS NumberCAS1333-74-0
CID NumberCID783
Gmelin NumberN/A
NSC NumberN/A
RTECS NumberRTECSMW8900000

Electrical properties
Electrical TypeN/A
Electrical ConductivityN/A
ResistivityN/A
Superconducting PointN/A

Magnetic properties
Magnetic TypeDiamagnetic
Curie PointN/A
Mass Magnetic Susceptibility-2.48×10-8
Molar Magnetic Susceptibility-4.999×10-11
Volume Magnetic Susceptibility-2.23×10-9

Abundances
% in Universe75%
% in Sun75%
% in Meteorites2.4%
% in Earth's Crust0.15%
% in Oceans11%
% in Humans10%

Atomic dimensions and structure
Atomic Radius53 pm
Covalent Radius37 pm
Van der Waals Radius120 pm
Crystal StructureSimple Hexagonal
Lattice Angles
π/2, π/2, 2 π/3
Lattice Constants
470, 470, 340 pm
Space Group NameP63/mmc
Space Group Number194

Nuclear Properties
Half-LifeStable
LifetimeStable
Decay ModeN/A
Quantum Numbers2S1/2
Neutron Cross Section0.332
Neutron Mass Absorption0.011
Known Isotopes
1H, 2H, 3H, 4H, 5H, 6H, 7H
Stable Isotopes
1H, 2H
Isotopic Abundances
1H99.9885%
2H0.0115%


Notes on the properties of Hydrogen:

Density: Density given for H at 0° Celsius. 2

Specific Heat: Value given for gas phase of H . 2

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

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