Periodic Table -> Thorium


Thorium Details

Thorium Symbol: Th

Thorium Atomic Number: 90

Thorium Atomic Weight: 232.038

What is Thorium?

Thorium (atomic number 90, symbol Th) is a metal and chemical element with radioactive properties. It was discovered by Jons Berzelius and Morten Esmark in 1828.

Thorium is an actinide metal that is ductile, soft, and silvery in color. It has a face-centered structure and is very reactive. The element forms different compounds, including halides, hydroxides, oxides, and chalcogenides. Thorium reacts with bismuth, antimony, arsenic, nitrogen, and other elements. Its boiling point is 8654 F (4790 C), and its melting point is 3182 F (1750 C). There are 6 isotopes that occur in nature, and Th-232 has the longest half life. The most common oxidation states are 4, 3, 2, and 1.

Occurrence and Production
This is an abundant element which is found in minerals such as thorium silicate, thorianite, monazite, and others. The metal is also found in minerals such as betafite, gadolinite, titanite, and zircon and in soils and rocks. In fact, many minerals contain small amounts of thorium and it is found on all continents. Different methods of production are used, including electrolysis, extraction, and decomposition. Sodium hydroxide is used to decompose minerals such as monazite.

Commercial and Industrial Applications
Thorium and its compounds have many applications and can be used as nuclear fuel. It is also used to produce refractory materials and alloys. One of its compounds, thorium oxide is used to produce nitric acid from ammonia and to manufacture glass and high-temperature cubicles. The element itself has applications in radiometric dating and is used to make ceramics and thorium mantles. Mantles are produced in facilities that have been relocated to the developing countries. Thorium is added to ophthalmic lenses and used to make welding rods. Alloys that contain thorium are used to make aerospace components.

Health Effects and Environmental Hazards
Exposure occurs through breathing, drinking water, and ingestion. Skin contact and smoking substances with thorium content are other routes of exposure. Naturally occurring thorium is found in animal and plant life, water, soil, and rocks. The element also contributes to radiation. Synthetically produced isotopes are rarely found in the environment. Thorium is usually released but small amounts get deposited in the bones. Overexposure increases the risk for liver problems, pancreas and lung cancer, and lung disease. Exposure is also associated with an increased risk of bone cancer. As a rule, the extent of exposure depends on factors such as health status, lifestyle, family traits, sex, and age. Other factors include route of exposure or pathway, duration, and dose or level.

People working or living near contaminated sites are at a higher risk. High levels of thorium are measured near industrial plants, government facilities, and mining areas. Special tests are used to measure exposure. Equipment is usually found in specialized laboratories and some state facilities. Persons working near contaminated sites use special equipment. Professionals such as radiation safety officers and health physicists who handle thorium are trained to detect and measure it. Water content is usually measured in analytical laboratories.

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