Hydrogen (H)

From Wikipedia, the free encyclopediaHydrogen is a chemical element with chemical symbol H and atomic number 1. With an atomic weight of 1.00794 u, hydrogen is the lightest element on the periodic table. Its monatomic form (H) is the most abundant chemical substance in the Universe, constituting roughly 75% of all baryonic mass.

Hydrogen in the periodic table

SymbolH
Atomic number1
Group1
Period1
Blocks
Element categoryNonmetal

Physical properties

Phase at STPGas
Density0.08988 g/cm3
Atomic weight1.0079 u
Melting point13.99 K
-259.16 °C
-434.488 °F
Boiling point20.271 K
-252.879 °C
-423.1822 °F

Atomära egenskaper

Electronegativity (Pauling Scale)2.2
Electron affinity72.769 kJ/mol
Ionization energies
11312 kJ/mol

Electron configuration

Electron configuration1s1
Electrons per shell1

History

Discovered1766
Discovered byHenry Cavendish
Named byAntoine Lavoisier