90 - Thorium actinide

Discovered by Jöns Jakob Berzelius in 1828

  • Atomic Radius (Å)
  • Cividis
Thorium

Thorium is a chemical element with symbol Th and atomic number 90. A radioactive actinide metal, thorium is one of only two significantly radioactive elements that still occur naturally in large quantities as a primordial element (the other being uranium). It was discovered in 1828 by the Norwegian Reverend and amateur mineralogist Morten Thrane Esmark and identified by the Swedish chemist Jöns Jakob Berzelius, who named it after Thor, the Norse god of thunder.

H He Li Be B C N O F Ne Na Mg Al Si P S Cl Ar K Ca Sc Ti V Cr Mn Fe Co Ni Cu Zn Ga Ge As Se Br Kr Rb Sr Y Zr Nb Mo Tc Ru Rh Pd Ag Cd In Sn Sb Te I Xe Cs Ba La Ce Pr Nd Pm Sm Eu Gd Tb Dy Ho Er Tm Yb Lu Hf Ta W Re Os Ir Pt Au Hg Tl Pb Bi Po At Rn Fr Ra Ac Th Pa U Np Pu Am Cm Bk Cf Es Fm Md No Lr Rf Db Sg Bh Hs Mt Ds Rg Cn Nh Fl Mc Lv Ts Og
57-71 La-Lu Lanthanides
89-103 Ac-Lr Actinides
 Shell Electrons Orbitals
122 in 1s
282 in 2s + 6 in 2p
3182 in 3s + 6 in 3p + 10 in 3d
4322 in 4s + 6 in 4p + 10 in 4d + 14 in 4f
5182 in 5s + 6 in 5p + 10 in 5d
6102 in 6s + 6 in 6p + 2 in 6d
722 in 7s
ThoriumThElectron 1Electron 2Electron 1Electron 2Electron 3Electron 4Electron 5Electron 6Electron 7Electron 8Electron 1Electron 2Electron 3Electron 4Electron 5Electron 6Electron 7Electron 8Electron 9Electron 10Electron 11Electron 12Electron 13Electron 14Electron 15Electron 16Electron 17Electron 18Electron 1Electron 2Electron 3Electron 4Electron 5Electron 6Electron 7Electron 8Electron 9Electron 10Electron 11Electron 12Electron 13Electron 14Electron 15Electron 16Electron 17Electron 18Electron 19Electron 20Electron 21Electron 22Electron 23Electron 24Electron 25Electron 26Electron 27Electron 28Electron 29Electron 30Electron 31Electron 32Electron 1Electron 2Electron 3Electron 4Electron 5Electron 6Electron 7Electron 8Electron 9Electron 10Electron 11Electron 12Electron 13Electron 14Electron 15Electron 16Electron 17Electron 18Electron 1Electron 2Electron 3Electron 4Electron 5Electron 6Electron 7Electron 8Electron 9Electron 10Electron 1Electron 2
silvery, often with black tarnish Appearance
232  u Atomic Mass
5.06k  K Boiling Point
4 Group
4 Common Oxidation States
2.06  Å Covalent Radius
11.7  g/cm³ Density
113  kJ/mol Electron Affinity
1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d10 5p6 6s2 4f14 5d10 6p6 7s2 6d2 Electron Configuration
[Rn] 6d2 7s2 Electron Configuration (semantic)
1.3 Electronegativity
90 Electrons
6.31  eV First Ionization Energy
4 ICSD Oxidation States
587, 1110, 1930, 2780  kJ/mol Ionization Energies
2.03k  K Melting Point
47 Mendeleev Number
26.2  J/(mol·K) Molar Heat
7 Number of Shells
142 Neutrons
90 Atomic Number
12 Number of Isotopes
2, 3, 4 Oxidation States
7 Period
Solid Phase
90 Protons
2, 8, 18, 32, 18, 10, 2 Electron Shell Occupations
0.113  J/(g K) Specific Heat