Everything about Chalcogen totally explained
The
chalcogens are the name for the
periodic table group 16 (old-style: VIB or VIA) in the
periodic table. It is sometimes known as the
oxygen family. It consists of the
elements oxygen (
O),
sulfur (
S),
selenium (
Se),
tellurium (
Te), the radioactive
polonium (
Po), and the synthetic
ununhexium (
Uuh). The compounds of the heavier chalcogens (particularly the
sulfides,
selenides, and
tellurides) are collectively known as
chalcogenides. Unless grouped with a heavier chalcogen,
oxides are not considered chalcogenides.
The name is generally considered to mean "ore former" from the
Greek chalcos "
ore" and
-gen "formation".
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Oxygen and sulfur are
nonmetals, and polonium, selenium and tellurium are
metalloid semiconductors (for example, their electrical properties are between those of a metal and an
insulator). Nevertheless, tellurium, as well as selenium, is often referred to as a metal when in elemental form.
Chalcogens are quite common as minerals. For example,
pyrite (FeS
2) is an
iron ore and AuTe
2 gave its name to the gold rush town of
Telluride, Colorado in the
United States.
The formal
oxidation number of the chalcogens is generally −2 in a chalcogenide but other values, such as −1 in pyrite, can be attained.
The highest formal oxidation number +6 is found in
sulfates,
selenates and
tellurates, such as in sodium selenate (Na
2SeO
4). Modern chemical understanding based on
quantum theory supersedes the use of formal oxidation numbers in favour of a
many-electron wavefunction approach allowing detailed computer simulation. The former concept, while flawed, is still useful in thought experiments.
Further Information
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