Chalcogen

Group	16
Period
2	Template:Element cell
3	Template:Element cell
4	Template:Element cell
5	Template:Element cell
6	Template:Element cell
7	Template:Element cell

Overview

The chalcogens (with the "ch" pronounced like a k) 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". [1]

Oxygen and sulfur are nonmetals, and polonium, selenium and tellurium are metalloid semiconductors (i.e., 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 (FeS₂) is an iron ore and AuTe₂ gave its name to the gold rush town of Telluride, Colorado in the United States.

The formal oxidation number of the chalcogen 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 (Na₂SeO₄). Modern chemical understanding based on quantum theory somewhat outdates the use of formal oxidation numbers in favour of a many-electron wavefunction approach allowing detailed computer simulation, though the concept, while flawed, is still useful in thought experiments.

Explanation of above periodic table slice:

bgcolor="Template:Element color/Nonmetals" | Nonmetals	bgcolor="Template:Element color/Metalloids" | Metalloids	bgcolor="Template:Element color/Poor metals" | Poor metals	Atomic numbers in Template:Element color/Gas are gases	Atomic numbers in Template:Element color/Solid are solids	style="border:Template:Element frame/Primordial;" | Solid borders indicate primordial elements (older than the Earth)	style="border:Template:Element frame/Natural radio;" | Dashed borders indicate radioactive natural elements	style="border:Template:Element frame/Synthetic;" | Dotted borders indicate radioactive synthetic elements

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See also

• Periodic table

External links

• A Second Note on the Term "Chalcogen"