Element Thorium, Th, Actinide or Actinoid
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Thorium History
In 1815, Jons Jakob Berzelius, examining samples ores from mines of Fahlun (Falun) mines, Sweden, obtained a material which he hastily called thorium. In spite of the fact that the conclusion was wrong, it was considered indisputable because of the great scientist's authority. The error was found by Berzelius himself after 10 years. In 1828 Prof. Esmark, having found a mineral in syenites from the island of Lovo, Norway, was unable to identify it as any known mineral, and he sent a specimen to Berzelius for examination. A chemical analysis of this mineral by Berzelius demonstrated that it contained of a silicon earth as well as of oxide of a new element which was again named after Thor, the ancient Scandinavian god of thunder. Berzelius failed in attempt of isolating the metal thorium. It was done by Lars Frederik Nilson in 1882. Thorium is a member of actinide (or actinoid) group of chemical elements.
Thorium Occurrence
Thorium-232 isotope is the most long-lived and is found in nature. Its crustal abundance is 8x10-4% by mass. Around 120 thorium-containing minerals are known, the most important of which are thorite ThSiO4, thorianite (Th,U)O2 and monazite which is the main industrial source of thorium. It is contained also in ilmenite, edisonite, cassiterite and rare earth elements ores. Š¢horium-230, a product of uranium decay is also found in nature. The commercial deposits were estimated in the beginning of 1980 1 million metric tons. The main deposits are located in India, Canada, USA, Norway and Brazil.
Thorium is constantly present in plant and animal tissues. Thorium accumulation coefficient which equals the ratio of concentration in organisms and environmental concentration is 1250 in sea plankton, 10 in benthic seaweed, - 50-300 in Invertebrata soft tissues and 100 in fish. The concentration in fresh water mollusks (Unio mancus) varies from 3x10-7 to 1x10-5%, and in sea animals from 3x10-7 to 3x10-6%.
Thorium is mostly absorbed by liver and spleen as well as by bone marrow, lymphatic glands and suprarenal capsules. It is poorly soaked by gastrointestinal tract.
Thorium Neighbours
Periodic Table | | | |