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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 ...
In air, thorium burns to form the binary oxide thorium dioxide, ThO 2, also called thoria or thorina. [20] Thoria, a refractory material, has the highest melting point (3390 °C) of all known oxides. [21]
The melting point of thorium oxide is 3300 °C – the highest of all known oxides. Only a few elements (including tungsten and carbon) and a few compounds (including tantalum carbide) have higher melting points. [6] All thorium compounds, including the dioxide, are radioactive because there are no stable isotopes of thorium.
The Gmelin rare earths handbook lists 1522 °C and 1550 °C as two melting points given in the literature, the most recent reference [Handbook on the chemistry and physics of rare earths, vol.12 (1989)] is given with 1529 °C.
Despite its (mild) radioactivity, thorium fluoride is used as an antireflection material in multilayered optical coatings. It has excellent optical transparency in the range 0.35–12 μm, and its radiation is primarily due to alpha particles, which can be easily stopped by a thin cover layer of another material.
Anhydrous thorium nitrate is a white substance. It is covalently bound with low melting point of 55 °C. [2]The pentahydrate Th(NO 3) 4 •5H 2 O crystallizes with clear colourless crystals [6] in the orthorhombic system.
The melting point of thorium dioxide (3350 °C) is greater than that of uranium dioxide (2800 °C), resulting in a need for increased sintering temperature or addition of non-reactive sintering aids to produce thorium dioxide-based fuel. [48]: 2 Thorium is a fertile material, rather than a fissile one. This means that the fuel must be used in ...
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 ...