Thorium
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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;
A thin square of thorium metal in a glass ampoule
Thor's Fight with the Giants (1872) by Mårten Eskil Winge; Thor, the Norse god of thunder, raising his hammer Mjölnir in a battle against the giants.
Jöns Jacob Berzelius, who first identified thorium as a new element
World War II thorium dioxide gas mantle
Actinium
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Actinium is a chemical element; it has symbol Ac and atomic number 89. It was discovered by Friedrich Oskar Giesel in 1902, who gave it the name emanium; the element got its name by being wrongly iden
Thorium
…a moderately soft, paramagnetic, bright silvery radioactive actinide metal that can be bent or shaped. In the periodic table, it lies to the right of actinium, to the left of protactinium, and below cerium. Pure thorium is very ductile and, as normal for metals, can be cold-rolled, swaged, and drawn. At room…
Uraninite ores have elevated concentrations of actinium.