Element 1
Hydrogen (H)
Hydrogen (H) is element 1 of the periodic table, a reactive nonmetal in period 1, group 1 (s-block) with an atomic mass of 1.008 and is a gas at standard conditions.
At a glance
- Atomic number
- 1
- Symbol
- H
- Atomic mass
- 1.008 u
- Category
- Reactive nonmetals
- Period
- 1
- Group
- 1
- Block
- s-block
- Phase at STP
- gas
Electron structure
- Electron configuration
- 1s1
- Shorthand configuration
- 1s1
- Electrons per shell
- 1
- Oxidation states
- -1, +1
Physical properties
- Melting point
- 14.01 K
- Boiling point
- 20.28 K
- Density
- 0.00008988 g/cm3
- Phase
- gas
Atomic properties
- Electronegativity (Pauling)
- 2.2
- Atomic radius
- 53 pm
- Covalent radius
- 31 pm
- Van der Waals radius
- 120 pm
- First ionization energy
- 1312 kJ/mol
- Electron affinity
- 73 kJ/mol
Notable isotopes
| Isotope | Mass | Abundance | Stability |
|---|---|---|---|
| H-1 | 1.00783 | 99.98% | Stable |
| H-2 | 2.0141 | 0.02% | Stable |
Common uses
- Rocket fuel
- Ammonia production
- Fuel cells
- Petroleum refining
Discovery
- Year
- 1766
- Discovered by
- Henry Cavendish
- Country
- England