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Hydrogen
HydrogenH Electron 1

Hydrogen 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.

1 Atomic Number
1.01  u Atomic Mass
14.18  K Melting Point
20.28  K Boiling Point
8.99e-5  g/cm³ Density
0.79  Å Atomic Radius
0.31  Å Covalent Radius
2.2 Electronegativity
13.6  eV First Ionization Energy
72.77 Electron Affinity
1 Number of Shells
1 Electron Valency
1 Electron Shell Occupations
14.3  J/g Specific Heat