The periodic table/Hydrogen
Hydrogen was discovered in 1776 by Henry Cavendish in London, UK. Antoine Lavoisier gave the element its name, derived from the Greek 'hydro' and 'genes' meaning water-forming.
Atomic Number: 1
Electron Configuration: 1s1
CAS Number: 133-74-0
Appearance: colourless gas
Discovery in: 1776
Key Isotopes: 1H, 2H
Density: 0.08988 g/L
Crystal Structure: hexagonal
Melting Point: -259.1 °C
Boiling Point: -252.9 °C
Hydrogen can form an explosive mixture from air. It is currently manufactured from methane gas, but can also be made through the electrolysis of water and aqueous salts. Hydrogen gas is used to make key materials like ammonia, cyclohexane and methanol, which are intermediates in the production of fertilisers, plastics and pharmaceuticals.
Large quantities of hydrogen are used in the Haber process and for the hydrogenation of oils from fats.
Hydrogen is part of the DNA molecule.
Hydrogen is found in the sun and most of the stars, and is the most abundant element in the universe. The planet Jupiter is composed mostly of hydrogen, and there is a theory that in the interior of the planet the pressure is so great that metallic hydrogen is formed from solid molecular hydrogen. On Earth, hydrogen is found in the greatest quantities in water, only being present in the atmosphere in small amounts - less than 1 part per million by volume.
Atomic radius: 1.100 Å
Covalent radius: 0.32 Å
Electron affinity: 72.7 kJ mol-1
First ionisation energy: 1312.0 kJ mol-1
Oxidation States and Isotopes
Common oxidation states: 1, -1
|Isotope||Atomic mass||Abundance (%)||Half life||Mode of decay|
Pressure and Temperature Data
Molar heat capacity: 28.836 J mol-1 K-1