90Th

Thorium

Actinidesolidblock f

A weakly radioactive actinide three times as abundant as uranium, once burnt in every gas lantern mantle and long proposed as a reactor fuel.

Atomic number	90
Standard atomic weight	232.04 g/mol ± 0.01
Group · period	f-block series · 7
Electron configuration	[Rn] 6d² 7s²

About Thorium

Thorium is one of only three elements past bismuth with a published standard atomic weight, because thorium-232's 14-billion-year half-life means essentially all of the primordial supply is still here and its isotopic composition is effectively fixed. Auer von Welsbach's 1891 gas mantle — thorium dioxide with 1 % ceria — made thorium a household material for decades, glowing brilliant white in a flame at 2000 °C. As a nuclear fuel it is fertile rather than fissile: absorb a neutron and thorium-232 becomes uranium-233. That cycle produces far less long-lived transuranic waste than the uranium cycle and was demonstrated at Oak Ridge in the 1960s molten-salt reactor experiment, but it never scaled, partly because it produced no plutonium.

Use 232.04 g/mol in these solvers

Moles from Mass (n = m/M)

n = \frac{m}{M}

Opens with M = 232.04 g/mol already filled in

Gas Density from Molar Mass

\rho = \frac{PM}{RT}

Opens with M = 232.04 g/mol already filled in

Faraday's Law of Electrolysis (m = QM/nF)

m = \frac{Q M}{n F}

Opens with M = 232.04 g/mol already filled in

Ion Concentration as CaCO₃ Equivalent

C_{\mathrm{CaCO_3}} = C_{\mathrm{ion}} \times \frac{50.04}{\mathrm{EW}}

Opens with EW = 232.04 g/mol already filled in

Acid Feed to Reduce Alkalinity

\dot m = \frac{\Delta \mathrm{Alk} \, Q \times \frac{\mathrm{EW}}{50.04}}{p/100\%}

Opens with EW = 232.04 g/mol already filled in

← 89 ActiniumPeriodic table91 Protactinium →