A method for determining quantity, capacity, or dimension.
All systems of measurement use units whose amounts have been arbitrarily set and agreed upon by a group of people.
Thorium metal has a bulk modulus (a measure of resistance to compression of a material) of 54 GPa, about the same as tin's (58.2 GPa).
Aluminium's is 75.2 GPa; copper's 137.8 GPa; and mild steel's is 160–169 GPa.
Several systems of measurement are in common use, notably the United States Customary System and the metric system.
The metric system has been officially adopted as the international standard for use in science, providing scientists all over the world with an efficient way of comparing the results of experiments conducted at different times and in different places.1.
At room temperature, thorium metal has a face-centred cubic crystal structure; it has two other forms, one at high temperature (over 1360 °C; body-centred cubic) and one at high pressure (around 100 GPa; body-centred tetragonal).
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. The most stable isotope, It is estimated to be over three times more abundant than uranium in the Earth's crust, and is chiefly refined from monazite sands as a by-product of extracting rare-earth metals.
Thorium was discovered in 1829 by the Norwegian amateur mineralogist Morten Thrane Esmark and identified by the Swedish chemist Jöns Jacob Berzelius, who named it after Thor, the Norse god of thunder.
Thorium is a weakly radioactive metallic chemical element with symbol Th and atomic number 90.
Thorium metal is silvery and tarnishes black when it is exposed to air, forming the dioxide; it is moderately hard, malleable, and has a high melting point.