View source for Chalcogen

{| align="right" style="margin:0 0 1em 1em;"
! [[Periodic table group|Group]]
! 16
|-
! [[Periodic table period|Period]]
|-
! [[Period 2 element|2]]
| {{element cell| 8|Oxygen|O| |Gas|Nonmetals|Primordial}}
|-
! [[Period 3 element|3]]
| {{element cell|16|Sulfur|S| |Solid|Nonmetals|Primordial}}
|-
! [[Period 4 element|4]]
| {{element cell|34|Selenium|Se| |Solid|Nonmetals|Primordial}}
|-
! [[Period 5 element|5]]
| {{element cell|52|Tellurium|Te| |Solid|Metalloids|Primordial}}
|-
! [[Period 6 element|6]]
| {{element cell|84|Polonium|Po| |Solid|Metalloids|Natural radio}}
|-
! [[Period 7 element|7]]
| {{element cell|116|Ununhexium|Uuh| |Solid|Poor metals|Synthetic}}
|}

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==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 [[chemical element|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 [[sulfide]]s, [[selenide]]s, and tellurides) are collectively known as '''chalcogenides'''.  Unless grouped with a heavier chalcogen, [[oxide]]s are not considered chalcogenides.

The name is generally considered to mean "ore former" from the [[Greek language|Greek]] ''chalcos'' "''ore''" and ''-gen'' "formation". [http://jchemed.chem.wisc.edu/Journal/Issues/1997/Sep/abs1063.html]

Oxygen and sulfur are [[nonmetal]]s, and polonium, selenium and tellurium are [[metalloid]] [[semiconductor]]s (i.e., their electrical properties are between those of a metal and an [[electrical insulation|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<sub>2</sub>) is an iron ore and AuTe<sub>2</sub> 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 [[sulfate]]s, selenates and tellurates, such as in sodium selenate (Na<sub>2</sub>SeO<sub>4</sub>). Modern chemical understanding based on [[quantum chemistry|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.

{|style="text-align: center;" border="0" cellpadding="2" 
|+ '''Explanation of above periodic table slice:'''
! bgcolor="{{element color/Nonmetals}}" | [[Nonmetal]]s
! bgcolor="{{element color/Metalloids}}" | [[Metalloid]]s
! bgcolor="{{element color/Poor metals}}" | [[Poor metal]]s
| Atomic numbers in <font color="{{element color/Gas}}">{{element color/Gas}}</font> are gases
| Atomic numbers in <font color="{{element color/Solid}}">{{element color/Solid}}</font> are solids
| style="border:{{element frame/Primordial}};" | Solid borders indicate [[primordial element]]s (older than the Earth)
| style="border:{{element frame/Natural radio}};" | Dashed borders indicate [[radioactive decay|radioactive]] natural elements
| style="border:{{element frame/Synthetic}};" | Dotted borders indicate radioactive [[synthetic element]]s
|}
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{{PeriodicTablesFooter}} 

== See also ==
* [[Periodic table]]

== External links ==
* [http://jchemed.chem.wisc.edu/Journal/Issues/2001/Oct/abs1333_1.html A Second Note on the Term "Chalcogen"]

[[Category:Periodic table]]
[[Category:Chalcogens|*]]

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