Page 34 - Curriculum Visions Dynamic Book

Thorium (Th)
Element 90.A silvery-white radioactive metal in the actinide series in the Periodic Table.Thorium metal does not oxidise easily; but when a small amount of thorium oxide is present, it oxidises quickly in air to a black colour.Thorium oxide has the highest melting point of all oxides (3,300°C).
 Thorium oxide accounts for the brilliant white glow of these gas mantles.
Technology
Thorium is added to magnesium alloys to improve their high-temperature strength. Thorium can be a source of nuclear power.The potential heat energy
from thorium is greater than that of uranium and fossil fuels combined. The radioactive heating in the Earth’s core may be mainly due to thorium.
Thorium oxide is used to impregnate camping lantern gas mantles and accounts for their brilliant white light. The oxide is also used for making high- quality camera lenses.
Geology
Thorium is not found as a native metal. The main thorium ores are thorite and thorianite. Most thorite is found in the mineral monazite sand with other rare earths.
Biology
Thorium is not found in living things. Since it is radioactive, it is a source
of danger to people exposed to it in unshielded environments.
Key facts...
Name: thorium
Symbol: Th
Atomic number: 90
Atomic weight: 232
Position in Periodic Table: inner transition metal;
period 7 (actinide series)
State at room temperature: solid Colour: silvery-white
Density of solid: 11.66 g/cc
Melting point: 1,750°C
Boiling point: 4,780°C
Origin of name: named after Thor, the
mythological Scandinavian god of war
Shell pattern of electrons: 2–8–18–32–18–10–2
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