H
Hydrogen
Element 1 · Reactive nonmetal
Hydrogen (H)
Hydrogen is the lightest and most abundant element in the universe. A colourless, flammable gas, it fuels the stars and forms water when it burns in oxygen.
- Reactive nonmetal
- Period 1
- Group 1
- s-block
- gas at room temperature
Key properties
- Atomic mass
- 1.008
- u
- Electron configuration
- 1s1
- Melting point
- -259.3 °C
- 13.81 K
- Boiling point
- -252.9 °C
- 20.28 K
- Density
- 0.0899 g/L
- Electronegativity
- 2.2
- Pauling
- Atomic radius
- 120 pm
- van der Waals
- 1st ionisation energy
- 13.598 eV
Compare with every element:Electronegativity chartAtomic radius chartIonisation energy chartDensity chart of the elementsMelting point chartElectron configuration chart
Did you know?
Notable facts about hydrogen
- 01
Roughly three out of every four atoms of ordinary matter in the universe are hydrogen.
- 02
The Sun fuses about 600 million tonnes of hydrogen into helium every second.
- 03
It is the only element whose isotopes have their own names: protium, deuterium and tritium.
Applications
What is hydrogen used for?
- Ammonia production for fertilisers
- Oil refining (hydrocracking)
- Fuel cells and rocket fuel
- Hydrogenation of fats and oils
History
Discovery & name origin
Discovered by
Year
Where
England
Name origin
Greek hydro + genes, “water-former” — named by Antoine Lavoisier because it burns to make water.
Atomic structure
Atomic properties
Atomic structure
Atomic properties
- Atomic number
- 1
- Atomic mass
- 1.008 u
- Group
- 1
- Period
- 1
- Block
- s-block
- Electron configuration
- 1s1
- Full configuration
- 1s1
- Electrons per shell
- 1
- Electronegativity (Pauling)
- 2.2
- Electron affinity
- 0.754 eV
- Atomic radius (van der Waals)
- 120 pm
- Stable isotopes
- 2
Oxidation states
Highlighted: common oxidation states (+1, -1).
Physical
Physical properties & colour
Physical
Physical properties & colour
- State at 20 °C
- Gas
- Melting point
- 13.81 K · -259.3 °C · -434.8 °F
- Boiling point
- 20.28 K · -252.9 °C · -423.2 °F
- Density
- 0.0899 g/L
- Molar heat capacity
- 28.836 J/(mol·K)
- Appearance
- Colourless gas
- CPK model colour
- Copied
The CPK colour is the convention used for this element’s atoms in molecular models.
FAQ
Hydrogen questions
What is H on the periodic table?
H is the symbol for hydrogen, element 1 on the periodic table. It sits in group 1, period 1, in the reactive nonmetal category, and has an atomic mass of 1.008.
What is the atomic number of hydrogen?
Hydrogen has atomic number 1, so every hydrogen atom has 1 protons in its nucleus. Its symbol is H and its atomic mass is 1.008.
Who discovered hydrogen?
Hydrogen was discovered by Henry Cavendish in 1766 (England). The name comes from Greek hydro + genes, “water-former” — named by Antoine Lavoisier because it burns to make water.
What is hydrogen used for?
Hydrogen is used for: ammonia production for fertilisers; oil refining (hydrocracking); fuel cells and rocket fuel; hydrogenation of fats and oils.
Is hydrogen a metal?
No. Hydrogen is classed as a reactive nonmetal.
What is the electron configuration of hydrogen?
The electron configuration of hydrogen is 1s1. Its 1 electrons are arranged in shells as 1.