Interchalcogen
The chalcogens react with each other to form interchalcogen compounds.
Although no chalcogen is extremely electropositive, nor quite as electronegative as the halogen fluorine, there is a large difference in electronegativity between the top and bottom of the group. Combined with the fact that there is a significant trend towards increasing metallic behaviour while descending the group, this causes the interchalcogens to display many different kinds of bonding: covalent, ionic, metallic, and semimetallic.
Bonding in the binary interchalcogens
Going down the above table, there is a transition from covalent bonding to ionic bonding; going across the table, there is a transition from ionic bonding to metallic bonding. For example, in the leftmost column of the table, and are purely covalent, and are polar molecules, forms chained polymers, forms layered polymers, and is ionic with the fluorite structure ; in the bottom row of the table, and PoS are ionic, and are semimetallic, and is metallic.Summary of known binary interchalcogens
Sulfur chalcogenides
- Lower sulfur oxides, where the ratio x:''y is greater than 1:2
- *Disulfur monoxide,
- *Disulfur dioxide,
- *Sulfur monoxide, SO
- Sulfur dioxide,
- Sulfur trioxide,
- Higher sulfur oxides, where x'' > 3
Selenium chalcogenides
- Selenium dioxide,
- Selenium trioxide,
- Many "alloys" of selenium and sulfur in different concentrations with semimetallic bonding,
- *"Selenium monosulfide", SeS
- *"Selenium disulfide",, actually a 2:1 mixture of cyclo- and cyclo-
- *"Selenium trisulfide",, actually occurring as an 8-membered cyclic compound, where two sulfur atoms in the molecule of cyclooctasulfur are replaced by selenium atoms
Tellurium chalcogenides
- Tellurium monoxide, TeO
- Tellurium dioxide,
- Tellurium trioxide,
- Ditellurium pentoxide,
- Many "alloys" of tellurium and sulfur in different concentrations with semimetallic bonding,
- Many "alloys" of tellurium and selenium in different concentrations with semimetallic bonding,
Polonium chalcogenides
- Polonium monoxide, PoO
- Polonium dioxide,
- Polonium trioxide,
- Polonium monosulfide, PoS
- Many "alloys" of polonium and selenium in different concentrations with semimetallic bonding,
- Many "alloys" of polonium and tellurium in different concentrations with semimetallic bonding,