![A periodic table element box for thorium shows atomic number 90, symbol Th, atomic weight 232.0377, electron configuration [Rn]6d2 7s2, and the name thorium. It highlights thorium as an actinoid element, solid at room temperature, with a face-centered cubic crystal structure and weakly basic acid-base properties.](https://cdn.britannica.com/10/22310-050-74745E38/Thorium.jpg)
thorium: References & Edit History
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Article Contributors
Primary Contributors
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Lester Morss
Adjunct Professor, Department of Chemistry, University of Maryland, College Park, Maryland.
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Article History
| Type | Description | Contributor | Date |
|---|---|---|---|
| Modified link of Web site: National Center for Biotechnology Information - Thorium. | Aug 07, 2026 | ||
| Add new Web site: Chemistry LibreTexts - Thorium The Future of Energy. | Mar 11, 2026 | ||
| Add new Web site: ABC listen - Counterpoint - Thorium: a future energy source? | Jan 28, 2026 | ||
| Add new Web site: National Cancer Institute - Thorium. | Sep 20, 2025 | ||
| Add new Web site: International Atomic Energy Agency - Thoriums Long-Term Potential in Nuclear Energy: New IAEA Analysis. | Aug 09, 2025 | ||
| Add new Web site: Energy Education - Thorium. | Jan 28, 2025 | ||
| Add new Web site: Massachusetts Institute of Technology - Abundant thorium as an alternative nuclear fuel. | Apr 22, 2024 | ||
| Add new Web site: Frontiers - Frontiers in Energy Research - An overview of thorium as a prospective natural resource for future energy. | Mar 01, 2024 | ||
| Added media. | Feb 29, 2024 | ||
| Add new Web site: U.S. Environmental Protection Agency - Radionuclide Basics: Thorium. | Nov 23, 2023 | ||
| Add new Web site: Lenntech - Thorium - Th. | Sep 28, 2023 | ||
| Add new Web site: National Center for Biotechnology Information - PubChem - Thorium. | Apr 13, 2023 | ||
| Add new Web site: World Nuclear Association - Thorium. | Jan 31, 2023 | ||
| Add new Web site: National Center for Biotechnology Information - Thorium. | Sep 28, 2022 | ||
| Add new Web site: Livescience - Facts About Thorium. | Jun 12, 2022 | ||
| Add new Web site: The Periodic Table - The Element Thorium. | May 03, 2021 | ||
| Corrected display issue. | Apr 21, 2017 | ||
| Add new Web site: Hyperphysics - Thorium. | May 12, 2014 | ||
| Add new Web site: Australian Government - Geoscience Australia - Thorium. | May 12, 2014 | ||
| Add new Web site: Making Music Fun! - Biography of Louis Armstrong. | May 12, 2014 | ||
| Add new Web site: U.S. Environmental Protection Agency - Thorium. | Jun 18, 2013 | ||
| Add new Web site: Mineralogy Database - Thorium. | Jun 18, 2013 | ||
| Add new Web site: Bhabha Atomic Research Centre - Thorium. | Jun 18, 2013 | ||
| Add new Web site: Chemicool - Thorium Element Facts. | Jun 18, 2013 | ||
| Add new Web site: Jefferson Lab - Thorium. | Jun 18, 2013 | ||
| Add new Web site: World Nuclear Association - Thorium. | Jun 18, 2013 | ||
| Add new Web site: Royal Society of Chemistry - Thorium. | Jun 18, 2013 | ||
| Add new Web site: EnvironmentalChemistry.com - Thorium. | Jun 14, 2013 | ||
| Article revised and updated. | Jun 13, 2013 | ||
| Half-life of thorium-232 modified from 1.41 x 1010 years to 1.40 x 1010 years. Half-life of thorium-229 modified from 7,340 years to 7,880 years. | Jan 25, 2011 | ||
| The word "actinide" was modified to "actinoid." | Jan 25, 2011 | ||
| Article revised and updated. | Apr 17, 2009 | ||
| Added new Web site: U.S. Environmental Protection Agency - Thorium. | Mar 24, 2009 | ||
| Added new Web site: Los Alamos National Laboratory's Chemistry Division - Thorium. | Mar 24, 2009 | ||
| Added new Web site: Webelements.com - Thorium. | Mar 24, 2009 | ||
| Added new Web site: World Nuclear Association - Thorium. | Mar 24, 2009 | ||
| Article revised and updated. | Apr 12, 2007 | ||
| Article added to new online database. | Jul 20, 1998 |
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