Chalcogen

Group → 16
↓ Period
2 8
O
3 16
S
4 34
Se
5 52
Te
6 84
Po
7 116
Uuh

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 element polonium (Po), and the synthetic element 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.[1]

The name is generally considered to mean "ore former" from the Greek chalcos "ore" and -gen "formation". [2]

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 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 (Na2SeO4). 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.

Explanation of above periodic table slice:
Nonmetals Metalloids Poor metals Atomic numbers in red are gases Atomic numbers in black are solids Solid borders indicate primordial elements (older than the Earth) Dashed borders indicate radioactive natural elements Dotted borders indicate radioactive synthetic elements
Periodic tables
Layouts
Standard · Vertical · Full names · Names and atomic weights · Text for last · Large table · Metals and nonmetals · Blocks · Valences · Inline f-block · 218 elements · Electron configurations · Atomic weights · Electronegativities · Alternatives · Crystal structure
Lists of elements by
Name · Atomic symbol · Atomic number · Atomic weight · Name etymology (after places, after people) · Discovery
Boiling point · Melting point · Density · Oxidation state · Abundance (in humans) · Nuclear stability · Hardness
Groups
1 (Alkalis) · 2 (Alkaline earths) · 3 · 4 · 5 · 6 · 7 · 8 · 9 · 10 · 11 · 12 · 13 · 14 · 15 (Pnictogens) · 16 (Chalcogens) · 17 (Halogens) · 18 (Noble gases)
Periods:
1 · 2 · 3 · 4 · 5 · 6 · 7 · 8
Other element categories
Metals · Transition metals · Metalloids · Nonmetals · Lanthanoids · Actinoids · Rare earths · Platinum group · Post-transition metals
Blocks
s-block · p-block · d-block · f-block · g-block

See also

External links

  1. ↑ US patent application 2007092648, "Chalcogenide solar cells", published 2007-04-26, assigned to Nanosolar, Inc. 
  2. ↑ A Second Note on the Term "Chalcogen"