1H1.008
Hydrogen
Other nonmetals · gas at STP · Block S
About
Hydrogen is the simplest and most abundant element in the universe, making up about 75% of its mass. It's a key component of water, all organic matter, and stars, where it fuels nuclear fusion through the proton-proton chain. Under standard conditions, it's a colorless, odorless, and highly flammable diatomic gas. Its unique properties and potential as a clean energy source make it a subject of intense research.
Atomic Properties
Atomic Number1
Atomic Weight1.008 u
Neutrons (common)0
Electron Configuration1s¹
Full Configuration1s¹
Electrons per Shell1
Electronegativity2.2
Electron Affinity72.8 kJ/mol
Oxidation States-1, +1
Covalent Radius37 pm
Van der Waals Radius120 pm
Periodic Table Position
Group1
Period1
BlockS
Chemical SeriesOther nonmetals
Physical Properties
State at STPgas
AppearanceColorless gas
Density at STP0 g/cm³
Crystal Structurehcp
Magnetic Orderingdiamagnetic
Speed of Sound1,310 m/s
Thermal Properties
Melting Point13.99 K
Boiling Point20.271 K
Triple Point13.803 K
Thermal Conductivity0.181 W/(m·K)
Specific Heat14.304 J/(g·K)
Molar Heat28.836 J/(mol·K)
Heat of Fusion0.117 kJ/mol
Heat of Vaporization0.904 kJ/mol
Abundance
In Earth's Crust1,400 ppm
In Ocean110,000 ppm
In Solar System750,000 ppm
In Human Body100,000 ppm
In Universe750,000 ppm
Discovery
Discovered byHenry Cavendish
Discovery Year1,766
Occurrenceprimordial
CAS Number1333-74-0
Electron Configuration
Energy
↿
2s
2p
3s
3p
4s
3d
4p
5s
4d
5p
6s
4f
5d
6p
7s
5f
6d
7p
Isotopes of Hydrogen
| Symbol ▲ | Mass (u) ▲ | Abundance ▲ | Half-life ▲ | Decay Mode ▲ |
|---|---|---|---|---|
| 1H | 1.007825 | 99.9885% | Stable | Stable |
| 2H | 2.014101 | 0.0115% | Stable | Stable |
| 3H | 3.016049 | Trace | 12.32 y | Beta Minus Decay |
| 4H | 4.027810 | — | 91 ys | Neutron Emission |
Interactive Visualization
Explore the 3D Bohr model of Hydrogen in our interactive viewer.
View 3D Model of Hydrogen