H
Hydrogen · element 1
Diatomic Nonmetal · Gas at room temperature
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.
Key facts
Atomic mass
1.008 u
how heavy one atom is
Phase (room temp.)
Gas
Density
0.08988 g/L
how tightly packed it is
Melting point
13.99 K (-259 °C)
when solid turns to liquid
Boiling point
20.271 K (-253 °C)
when liquid turns to gas
Period
1
its row in the periodic table
Group
1
its column in the periodic table
Block
S-block
the neighbourhood it lives in
Electronegativity
2.2
how strongly it pulls electrons
Electron configuration
1s1
where its electrons live
Shells
1
electrons in each layer, inside to out
Discovered by
Henry Cavendish
who found it
Named by
Antoine Lavoisier
who gave it its name
Appearance
colorless gas
what it looks like
Source: Wikipedia