1 H 1.008

Hydrogen

DIATOMIC NONMETAL

Phase: Gas

Discovered: Henry Cavendish

Block: S

Summary

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.

Appearance: colorless gas

Source: Wikipedia

Physical Properties

Atomic Mass 1.008 u

Density 0.08988 g/cm³

Melting Point 13.99 K

Boiling Point 20.271 K

Molar Heat 28.836 J/(mol·K)

Electron Affinity 72.769 kJ/mol

Ionization Energies

1^st: 1312 kJ/mol