Periodic table / Thorium

Overview

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.

Electron configuration

The electron configuration of Thorium is [Rn] 6d2 7s2, with electron shells of 2, 8, 18, 32, 18, 10, 2.

Physical and chemical properties

Thorium is classified as a actinide. It has an atomic mass of 232.038 and exists as a solid at standard conditions, appearing as silvery, often with black tarnish.

Real-world uses of Thorium

Thorium is an actinide studied primarily in nuclear science and research due to its radioactive properties.

Interesting facts about Thorium

• Thorium has the atomic number 90 and chemical symbol Th.
• It belongs to period 7, group 3 of the periodic table.
• Thorium was discovered by Jöns Jakob Berzelius.

Explore Thorium interactively

Want to compare Thorium with other elements or see it highlighted on the full table? Open the interactive periodic table and click on Th to explore properties, trends, and neighboring elements. You can also test your knowledge with our periodic table quiz game.