Thorium
Thorium is a chemical element; it has symbol Th and atomic number 90. Thorium is a weakly radioactive light silver metal which tarnishes olive grey when it is exposed to air, forming thorium dioxide; it is moderately soft, malleable, and has a high melting point. Thorium is an electropositive actinide whose chemistry is dominated by the +4 oxidation state; it is quite reactive and can ignite in air when finely divided.
All known thorium isotopes are unstable. The most stable isotope, 232Th, has a half-life of 14.0 billion years, or about the age of the universe; it decays very slowly via alpha decay, starting a decay chain named the thorium series that ends at stable 208Pb. On Earth, thorium and uranium are the only elements with no stable or nearly-stable isotopes that still occur naturally in large quantities as primordial elements. Thorium is estimated to be over three times as abundant as uranium in the Earth's crust, and is chiefly refined from monazite sands as a by-product of extracting rare-earth elements.
Thorium was discovered in 1828 by the Swedish chemist Jöns Jacob Berzelius during his analysis of a new mineral found by Morten Thrane Esmark in Norway on Lovoya island near Brevik in the Langesund fjord. He named it after Thor, the Norse god of thunder and war. Its first applications were developed in the late 19th century. Thorium's radioactivity was widely acknowledged during the first decades of the 20th century. In the second half of the 20th century, thorium was replaced in many uses due to concerns about its radioactive properties.
Thorium is still used as an alloying element in TIG welding electrodes but is slowly being replaced in the field with different compositions. It was also material in high-end optics and scientific instrumentation, used in some broadcast vacuum tubes, and as the light source in gas mantles, but these uses have become marginal. It has been suggested as a replacement for uranium as nuclear fuel in nuclear reactors, and several thorium reactors have been built. Thorium is also used in strengthening magnesium, coating tungsten wire in electrical and welding equipment, controlling the grain size of tungsten in electric lamps, high-temperature crucibles, and glasses including camera and scientific instrument lenses. Other uses for thorium include heat-resistant ceramics, aircraft engines, and in light bulbs. Ocean science has used 231Pa/230Th isotope ratios to understand the ancient ocean.
The Bastard
- 2024-09-20T00:00:00.000000Z
Danmark
- 2022-04-29T00:00:00.000000Z
Feral Creation
- 2008-02-18T00:00:00.000000Z
Pest
- 2024-09-06T00:00:00.000000Z
Eclipsed
- 2024-07-11T00:00:00.000000Z
Underground
- 2024-07-11T00:00:00.000000Z
My Decay
- 2022-02-25T00:00:00.000000Z
War is Coming
- 2022-01-14T00:00:00.000000Z
Tengil
- 2019-04-05T00:00:00.000000Z
Depravity
- 2018-07-13T00:00:00.000000Z
Penance
- 2018-05-04T00:00:00.000000Z
Maniac
- 2018-03-09T00:00:00.000000Z
Cast from Hell
- 2008-12-14T00:00:00.000000Z
Similar Artists