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.
Source: WikipediaPhysical Properties
Atomic Mass 1.008 u
Density 0.08988 g/cm³
Melting Point 13.99 K
Boiling Point 20.271 K