Oxygen

Koushik 26/06/2026 19:58:08 Updated 26/06/2026 19:58:08

Property	Value
Atomic Number	8
Element	Oxygen
Symbol	O
Atomic Mass	15.999 u
Number of Neutrons	8 (most common isotope, Oxygen-16)
Number of Protons	8
Number of Electrons	8
Period	2
Group	16
Phase	Gas
Radioactive	No
Natural	Yes
Metal	No
Nonmetal	Yes
Metalloid	No
Type	Diatomic Nonmetal
Atomic Radius	48 pm
Electronegativity	3.44 (Pauling scale)
First Ionization Energy	13.618 eV
Density	0.001429 g/cm³
Melting Point	−218.79 °C
Boiling Point	−182.96 °C
Number of Isotopes	3 (Oxygen-16, Oxygen-17, Oxygen-18)
Discoverer	Carl Wilhelm Scheele, Joseph Priestley
Year	1774
Specific Heat	0.918 J/g·K
Number of Shells	2
Number of Valence Electrons	6