Hydrogen (H)
Hydrogenium
Hydrogen (H) is a non-metal in period 1, group 1. Its relative atomic mass is 1.008 and the molar mass of the atom is 1.008 g/mol; the molar mass of H₂ is 2.016 g/mol.
Atomic number 1
Atomic mass 1.008
Molar mass 1.008 g/mol H₂: 2.016 g/mol
Category Non-metal Gas
Properties of hydrogen
| Atomic number | 1 |
|---|---|
| Symbol | H |
| Latin name | Hydrogenium |
| Relative atomic mass | 1.008 |
| Molar mass | 1.008 g/mol · H₂: 2.016 g/mol |
| Group, period, block | 1, 1, s |
| Category | Non-metal |
| State at 20 °C | Gas |
| Electron configuration | 1s¹ |
| Valency / oxidation states | I / −1, +1 |
| Electronegativity (Pauling) | 2.2 |
| Melting / boiling point | −259.16 °C / −252.88 °C |
| Density | 0.0899 g/L |
| Atomic radius | 25 pm |
| Discovered | 1766, Henry Cavendish |
Electron configuration of hydrogen
Electrons per shell
K1
Full notation
1s¹
Noble-gas notation
1 proton · 1 electron1s¹
Formula and compounds of hydrogen
Simple substanceH₂hydrogenMolar mass of H₂: 2.016 g/mol
Oxides- H₂Owater
- HClhydrochloric acid
- H₂SO₄sulfuric acid
- NH₃ammonia
- CH₄methane
- H₂O₂hydrogen peroxide
Interesting facts about hydrogen
- 1The lightest and most abundant element in the universe — about 74% of ordinary matter by mass.
- 2Hydrogen is 14 times lighter than air, which is why it once filled airships.
- 3The nucleus of its most common isotope has no neutrons at all.
Uses of hydrogen
- Making ammonia for fertilisers
- Fuel cells and hydrogen vehicles
- Hardening vegetable oils (margarine)
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Frequently asked questions
The relative atomic mass of hydrogen is 1.008, so the molar mass of the atom is 1.008 g/mol; the molar mass of H₂ is 2.016 g/mol.
Full: 1s¹. Noble-gas notation: 1s¹.
Valency: I. Oxidation states: −1, +1.