Atomic Properties of Th
- Atomic Number of Th
- 90
- Atomic Mass of Th
- 232.0400 u
- Electron Configuration
- [Rn] 6d2 7s2
- Electronegativity
- 1.30
- Block
- f-block
- Group
- —
- Period
- 7
Jöns Jacob Berzelius identified thorium in a Norwegian mineral in 1828 and named it for Thor, the Norse god of thunder. Natural thorium is dominated by thorium-232, whose half-life is about 14 billion years. Its slow decay makes an individual gram less active than many shorter-lived radionuclides, but “weakly radioactive” does not remove inhalation, ingestion, daughter-product, or long-term exposure concerns.
Thorium-232 is fertile, not fissile with ordinary thermal neutrons. After capturing a neutron and passing through radioactive intermediates, it can become uranium-233, which can sustain fission. Proposed thorium fuel cycles use that pathway in several reactor concepts. They may offer resource or waste-profile advantages in particular designs, while still requiring reactors, fuel processing, safeguards, waste management, and control of radioactive products. Thorium is not a ready-made safer reactor in elemental form.
Historical thorium compounds appeared in gas mantles and high-index optical glass, applications reduced or changed because of radiation and manufacturing concerns. Thorium alloys and catalysts have also had specialized roles. Modern interest is centered chiefly on nuclear research and potential fuel systems.
The metal occurs in minerals such as monazite and forms part of a natural decay series. Its chemistry and dust require controlled handling.
This Corebound visionary is patient because its central story spans enormous timescales. A nucleus can wait billions of years to decay or capture a neutron and enter a fuel cycle. The potential is real, but every claimed benefit belongs to a complete engineered system, not to thorium alone.