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90 Th
Element Revision Sheet

Thorium (Th)

Actinoids Block F Group Actinides • Period 7
Superhero Identity

"The Thunder God, a potential hero for a new age of safer nuclear energy."

A memorable persona to anchor Th in your mind.

Density

11.72

Grams per cm³

Melting Point

1750

Celsius (°C)

Atomic Radius

237

Radius (pm)

Everyday Connection

Daily Life Link

Thorium is found in the mantle in an old gas-powered camping lantern.

Discovery & History

Year Discovered

1828

Discovered By

Jöns Jacob Berzelius

Origin of Name

"Thorium is named after Thor, the Scandinavian god of war."

Technical Properties

Atomic Mass

232.038 u

Standard State

solid

Boiling Point

4785°C

Electron Configuration

[Rn] 6d27s2

1st Ionization Energy

6.08 eV

Electron Affinity

N/A

Oxidation States

[+4]
Appearance

"Thorium is a weakly radioactive, silvery metal."

Did You Know?

1

It is named after Thor, the powerful hammer-wielding god of thunder in Norse mythology.

2

Thorium is being extensively researched as a potentially safer and more abundant alternative to uranium as a fuel for nuclear power plants.

3

Old gas camping lanterns used a 'mantle' containing thorium dioxide, which would glow with a bright white light when heated by a flame.

4

High-quality camera lenses made in the mid-20th century often contained thorium oxide to increase their refractive index, but these lenses are slightly radioactive.

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