Discovered By: Jons Jacob Berzelius
Discovery year: 1829

The following table showing some properties of Thorium(Th):

Table Example
Atomic number 90
Group n/a
Period 7
Block f
Electrons 90
Protons 90
Neutrons 142
Atomic weight 232.0377
Oxidation states +4
Ionic charge Th^4+


Table Example
Electrons per shell K2 L8 M18 N32 O18 P10 Q2
Electron configuration 1s^2 2s^2 2p^6 3s^2 3p^6 4s^2 3d^10 4p^6 5s^2 4d^10 5p^6 6s^2 4f^14 5d^10 6p^6 7s^2 6d^2
Covalent radius 206 pm
Boiling point 4820°C
Melting point 1750°C
Phase Solid
Fusion heat 16 kJ.mol^-1
Vaporization heat 530 kJ.mol^-1
Thermal expansion 1.1*10^-5 K^-1
Color Silver


Table Example
Brinell hardness 400 MPa
Bulk modulus 54 GPa
Density 11724 kg.m^-3
Mohs hardness 3
Molar volume 1.9792*10^-5 m^3.mol^-1
Poisson ratio 0.27
Shear modulus 31 GPa
Sound speed 2490 m.s^-1
Vickers hardness 350 MPatd>
Young's modulus 79 GPa


Table Example
Electical type Conductor
Magnetic type Paramagnetic
Resistivity 1.5*10^-7 Ohm.m
Superconducting point 1.38 K
Electronegativity 1.3
Valence 4
First ionization energy 587 kJ.mol^-1
Radioactive Yes
Half life 4.434*10^17 s
Lifetime 6.397*10^17 s
Neutron cross section 7.4 barn
Decay mode Alpha emission (α-decay)