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 (-259.14 °C)
- Boiling point
- 20.28 K (-252.87 °C)
- 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
Frequently asked questions
- Is hydrogen a metal?
- No. Hydrogen is a nonmetal, classified as a reactive nonmetal on the periodic table.
- How many protons does hydrogen have?
- Hydrogen has 1 protons. Its atomic number is 1, which is also the number of electrons in a neutral atom of hydrogen.
- What group and period is hydrogen in?
- Hydrogen is in group 1 and period 1 of the periodic table, in the s-block.
- What is the atomic mass of hydrogen?
- The atomic mass of hydrogen is 1.008 u (unified atomic mass units).
Keep exploring
Hydrogen's row is on the printable element property sheet, and its tile is on the periodic table wall chart - the same numbers as above, laid out for A4 or A3 paper.