Thorium

Koushik 26/06/2026 19:58:09 Updated 26/06/2026 19:58:09

Property	Value
Atomic Number	90
Element	Thorium
Symbol	Th
Atomic Mass	232.038 u
Number of Neutrons	142 (most common isotope, Thorium-232)
Number of Protons	90
Number of Electrons	90
Period	7
Group	Actinide (no fixed group number)
Phase	Solid
Radioactive	Yes
Natural	Yes
Metal	Yes
Nonmetal	No
Metalloid	No
Type	Actinide
Atomic Radius	237 pm
Electronegativity	1.30 (Pauling scale)
First Ionization Energy	6.307 eV
Density	11.72 g/cm³
Melting Point	1750 °C
Boiling Point	4788 °C
Number of Isotopes	No stable isotopes (Th-232 most notable)
Discoverer	Jöns Jacob Berzelius
Year	1828
Specific Heat	0.113 J/g·K
Number of Shells	7
Number of Valence Electrons	4