Page 31 - Curriculum Visions Dynamic Book

Tellurium (Te)
Element 52.A silvery-grey solid with
a metallic lustre or dark grey powder. It is a brittle metalloid (with properties between a metal and a non-metal) in group 6 (the oxygen group) in the Periodic Table. It has properties very similar to selenium.
Tellurium is a poor conductor of heat and a moderate conductor of electricity. It burns in air with a blue–green flame. Molten tellurium corrodes iron, copper, and stainless steel.
Discovery
It was discovered in gold ore in 1782 in Romania by Franz Joseph Müller von Reichenstein. It was named by Martin Heinrich Klaproth, who isolated it
in 1798.
Technology
Tellurium is a p-type semi-conductor.
It can be doped with silver, copper, gold and tin, but it has not been widely used. Tellurium added to copper and stainless steels as an alloy makes it easier to machine these metals.When added to lead, it makes it less susceptible to corrosion by sulphuric acid.Tellurium is also used in blasting caps.
Geology
Tellurium does occur in small amounts as a native element, but usually as gold telluride (calaverite). It is extracted from the muds that are produced during
the electrolytic refining of copper.The famous town of Telluride in the Colorado Rockies is named after a deposit of the gold telluride ore.
Biology
Tellurium is not found in living things. However, when even tiny amounts
are present in the air (as when mining telluride ores), the effect is to make
the breath smell like garlic. It is called ‘tellurium breath’ by miners. Its compounds are probably toxic.
Key facts...
Name: tellurium
Symbol: Te
Atomic number: 52
Atomic weight: 127.6
Position in Periodic Table: group 6 (16)
(oxygen group; chalcogen); period 5 State at room temperature: solid Colour: silvery-grey
Density of solid: 6.24 g/cc
Melting point: 449.8°C
Boiling point: 989.9°C
Origin of name: from the Latin word tellus,
meaning earth
Shell pattern of electrons: 2–8–18–18–6
31