1H1.008
Diatomic Non-Metals-block
Hydrogen
Element 1 on the periodic table, symbol H, group 1, period 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.
Appearance: colorless gas
Properties
- Atomic Number
- 1
- Atomic Mass
- 1.0080 u
- Group
- 1
- Period
- 1
- Block
- s-block
- Category
- Diatomic Non-Metal
- State at 25 °C
- Gas
- Melting Point
- 14 K · -259.2 °C
- Boiling Point
- 20.3 K · -252.9 °C
- Density
- 0.08988 g/L
- Atomic Radius
- 25 pm
- Electronegativity
- 2.2
- Oxidation States
- -1, +1
- Abundance in Crust
- 1,400 mg/kg
- Discovered
- 1766
- Discovered By
- Henry Cavendish
Electron Configuration
1s1
1s1
Ionisation Energies (kJ/mol)
- 1. 1,312
Elements near Hydrogen
Elements in the same group share the number of outer electrons and behave in similar ways. Elements in the same period share a shell, so they change steadily from left to right.