(i) Electronic configuration: They all have six electrons in the outermost shell and have ns² np⁴ general electronic configuration.
(ii) Oxidation state: The outer configuration of all these elements is ns² np⁴. Therefore, they complete their octet either by gaining two electrons or by sharing two electrons. Two types of oxidation states are shown by these elements.
(a) Negative oxidation state: Except the compound OF₂ oxygen shows-2 oxidation state in all its compounds. Due to hgh electronegativity, it forms O²' ion in most of the metal oxides.
The electronegativities of S, Se, Te are low hence their compounds even with most electropositive elements are not more than 50% ionic. Hence S^2–', Se^2–' and Te^2–' are less probable. Being a metal Po does not form Po²⁺ ion at all.
(b) Positive oxidation state: Oxygen does not show positive oxidation state except OF₂(O = + 2). With the increase in atomic number of electro negativity is decreasd in this group, hence the tendency to show the positive oxidation states will increase. S, Se, Te, Po show + 4, +6 oxidation state in addition to + 2.
(iii) Hydride formation: All the elements O, S, Se, Te and Po form M₂M type hydrides (where M = O, S, Se, Te and Po)