This chapter focuses on the first two elements of the group: oxygen and sulfur. There is a section each on dioxygen and ozone, oxygen and dioxygen coordination compounds, and structure of water and ices (including protonated water species). For sulfur, coverage includes its allotropes and polyatomic sulfur species, metal complexes with sulfide anions as ligands, and oxides and oxoacids of sulfur. Finally, there is a section on the allotropes and stereochemistry of selenium and tellurium, as well as the polyatomic anions and cations of these elements.
Keywords: allotropes, clathrate, dioxygen complexes, oxo-acids of sulfur, oxo ligand, ozone, peroxides, stereochemistry of selenium, stereochemistry of tellurium, sulfur oxides