Chalcogen

The elements of the sixth group of the periodic system are chalcogens ( " Erzbildner ", from Greek: Χαλκός, " copper, bronze ," and γεννάω, " create " ) called. The group is named after the first element as oxygen group. After the recent IUPAC numbering of the groups is the group 16 This group of substances includes the elements oxygen, sulfur, selenium, tellurium, polonium and the Livermorium artificially produced.

Occurrence

The chalcogens are found mostly in the form of ores and minerals in nature. Among the oxides and metal chalcogenides sulfides most commonly occur. Examples of oxides, the gaseous carbon dioxide in the atmosphere, and the solid silica ( crystalline than quartz, for example ), which forms the main component of the earth's crust. The sulphides include among others the minerals galena, cinnabar, pyrite, zinc sulfide and chalcopyrite. Less common are the selenides such as copper selenide and silver telluride Telluride eg. There are also other metal chalcogen compounds such as sulfites, sulfates and selenates.

Oxygen and sulfur are also elementary moment ( oxygen component of air, and dissolved in water, sulfur often respond in connection with volcanic exhalations containing hydrogen sulphide and sulfur dioxide, and sulfur, and also sulfuric acid).

Properties

Physical Properties

The chalcogens low atomic number are non- metals, with selenium and tellurium also metallic modifications exist: selenium and tellurium are, in principle, semi-metals, polonium and Livermorium metals. The physical properties are graded in order of increasing atomic mass. So take from oxygen to tellurium density, melting and boiling points to.

Chemical Properties

Chalcogenides react with metals to earthy and partly basic Metallchalkogenen (oxides, sulfides, etc.). With hydrogen they react to Chalkogenwasserstoffen (water, hydrogen sulfide, hydrogen selenide, etc.), which compounds analogous sum formulas, H2X have.

Chalcogens form among themselves compounds such as the sulfur oxides or sulfides of selenium. Chalcogen oxides form acids with water together such as sulphurous acid, the selenious acid and tellurous acid ( molecular formula H2XO3 ) from the dioxides and sulfuric acid and selenium telluric acid ( molecular formula H2XO4 ) from the trioxides.