Chalcogen

group 1616chalcogensgroup 16 elementgroup VI16 (Chalcogens)chalcohalideGroup 16 elementsoxygen elementsoxygen family
The chalcogens are the chemical elements in group 16 of the periodic table.wikipedia
416 Related Articles

Oxygen

OO 2 molecular oxygen
It consists of the elements oxygen (O), sulfur (S), selenium (Se), tellurium (Te), and the radioactive element polonium (Po).
It is a member of the chalcogen group in the periodic table, a highly reactive nonmetal, and an oxidizing agent that readily forms oxides with most elements as well as with other compounds.

Tellurium

Tenative telluriumtelluride
It consists of the elements oxygen (O), sulfur (S), selenium (Se), tellurium (Te), and the radioactive element polonium (Po).
Tellurium is chemically related to selenium and sulfur, all three of which are chalcogens.

Livermorium

Lv116element 116
The chemically uncharacterized synthetic element livermorium (Lv) is predicted to be a chalcogen as well.
It is a member of the 7th period and is placed in group 16 as the heaviest chalcogen, although it has not been confirmed to behave as the heavier homologue to the chalcogen polonium.

Group (periodic table)

groupgroupsChemical series
The chalcogens are the chemical elements in group 16 of the periodic table.
For example, group 16 is also described as the "oxygen group" and as the "chalcogens".

Atomic radius

atomic radiiatomicatomic size
They have relatively low atomic radii, especially the lighter ones. Density, melting and boiling points, and atomic and ionic radii tend to increase towards the chalcogens with higher atomic numbers.

Nonmetal

non-metalReactive nonmetalnon-metals
Oxygen, sulfur, and selenium are nonmetals, and tellurium is a metalloid, meaning that its chemical properties are between those of a metal and those of a nonmetal.
The elements generally classified as nonmetals include one element in group 1 (hydrogen); one in group 14 (carbon); two in group 15 (nitrogen and phosphorus); three in group 16 (oxygen, sulfur and selenium); most of group 17 (fluorine, chlorine, bromine and iodine); and all of group 18 (with the possible exception of oganesson).

Valence electron

valencevalence orbitaloutermost electron
All of the chalcogens have six valence electrons, leaving them two electrons short of a full outer shell.

Hydrogen chalcogenide

chalcogen hydridechalcogenideschemical analog to water
All hydrogen chalcogenides are toxic except for water.
Hydrogen chalcogenides (also chalcogen hydrides or hydrogen chalcides) are binary compounds of hydrogen with chalcogen atoms (elements of group 16: oxygen, sulfur, selenium, tellurium, and polonium).

Lone pair

lone electron pairlone pairsfree electron pair
For covalent bonding a chalcogen may accept two electrons according to the octet rule, leaving two lone pairs.
A single lone pair can be found with atoms in the nitrogen group such as nitrogen in ammonia, two lone pairs can be found with atoms in the chalcogen group such as oxygen in water and the halogens can carry three lone pairs such as in hydrogen chloride.

Chalcogenide

transition metal dichalcogenidechalcogenidesdichalcogenide
Although all group 16 elements of the periodic table, including oxygen, can be defined as chalcogens, oxygen and oxides are usually distinguished from chalcogens and chalcogenides.
Although all group 16 elements of the periodic table are defined as chalcogens, the term chalcogenide is more commonly reserved for sulfides, selenides, tellurides, and polonides, rather than oxides.

Organoselenium chemistry

organoselenium compoundallylic oxidationselenoxide
There are some organic selenium compounds, such as selenoproteins.
Selenium belongs with oxygen and sulfur to the group 16 elements or chalcogens, and similarities in chemistry are to be expected.

Oxide

oxidesmetal oxideO
It commonly bonds with many metals and metalloids to form oxides, including iron oxide, titanium oxide, and silicon oxide. Oxygen ions often come in the forms of oxide ions, peroxide ions, and hydroxide ions.
Even the chemical formula of O 4, tetraoxygen, is predictable as a group 16 element.

Interchalcogen

Chalcogen compounds form a number of interchalcogens.
The chalcogens react with each other to form interchalcogen compounds.

Fluorine

Ffluorofluorinated
Oxygen is the most electronegative element except for fluorine, and forms compounds with almost all of the chemical elements, including some of the noble gases.
Chalcogens have diverse fluorides: unstable difluorides have been reported for oxygen (the only known compound with oxygen in an oxidation state of +2), sulfur, and selenium; tetrafluorides and hexafluorides exist for sulfur, selenium, and tellurium.

Zinc

ZnZn 2+ zinc alloy
There are also compounds in which alkali metals and transition metals such as the fourth period transition metals except for copper and zinc.
Zinc is a chalcophile, meaning the element is more likely to be found in minerals together with sulfur and other heavy chalcogens, rather than with the light chalcogen oxygen or with non-chalcogen electronegative elements such as the halogens.

Pyrite

iron pyritepyritesfool's gold
Other oxidation numbers, such as −1 in pyrite and peroxide, do occur.
The pyrite structure is also used by other compounds MX 2 of transition metals M and chalcogens X = O, S, Se and Te.

Ionic radius

ionic radiiionicradius
Density, melting and boiling points, and atomic and ionic radii tend to increase towards the chalcogens with higher atomic numbers.
A thorough analysis of the bonding geometry was recently carried out for pyrite-type compounds, where monovalent chalcogen ions reside on C 3 lattice sites.

Hydroxide

OHhydroxide ionOH −
Oxygen ions often come in the forms of oxide ions, peroxide ions, and hydroxide ions.
In the higher oxidation states of the pnictogens, chalcogens, halogens, and noble gases there are oxoacids in which the central atom is attached to oxide ions and hydroxide ions.

Gallium

GaGa 2 67 Ga
The boron group metals aluminum, gallium, and indium also form bonds to chalcogens.
Gallium reacts with the chalcogens only at relatively high temperatures.

Group 6 element

group 66group 6 elements
Chromium, molybdenum, tungsten, and uranium were sometimes included in this group, but they would be later rearranged as part of group VIB; uranium would later be moved to the actinide series.
That group is now called group 16.

Metalloid

metalloidsMetallicmetalloid staircase
Oxygen, sulfur, and selenium are nonmetals, and tellurium is a metalloid, meaning that its chemical properties are between those of a metal and those of a nonmetal. It commonly bonds with many metals and metalloids to form oxides, including iron oxide, titanium oxide, and silicon oxide.
The increase in metallic character evident in tellurium, as compared to the lighter chalcogens, is further reflected in the reported formation of various other oxyacid salts, such as a basic selenate 2TeO 2 ·SeO 3 and an analogous perchlorate and periodate 2TeO 2 ·HXO 4.

Germanium

GeGe diodesGerman
Chalcogens form single bonds and double bonds with other carbon group elements than carbon, such as silicon, germanium, and tin.
Binary compounds with other chalcogens are also known, such as the disulfide, diselenide, and the monosulfide (GeS), selenide (GeSe), and telluride (GeTe).

Heavy metals

heavy metalheavy elementsheavy element
Selenium can protect against heavy metal poisoning.
The United States Pharmacopeia includes a test for heavy metals that involves precipitating metallic impurities as their coloured sulfides." In 1997, Stephen Hawkes, a chemistry professor writing in the context of fifty years' experience with the term, said it applied to "metals with insoluble sulfides and hydroxides, whose salts produce colored solutions in water and whose complexes are usually colored". On the basis of the metals he had seen referred to as heavy metals, he suggested it would useful to define them as (in general) all the metals in periodic table columns 3 to 16 that are in row 4 or greater, in other words, the transition metals and post-transition metals. The lanthanides satisfy Hawkes' three-part description; the status of the actinides is not completely settled.

Selone

selenoketoneselenocarbonyl
There are also thioketones, selenoketones, and telluroketones.
In constast to analogous structures with earlier chalcogens, selones greater steric and electronic stabilization.

Gold chalcogenides

gold telluridegold telluridesgold tellurides and sulfides
Gold chalcogenides are compounds formed between gold and one of the chalcogens, elements from group 16 of the periodic table: oxygen, sulfur, selenium, or tellurium.