Redox chemistry

The elements Cl, O, F, and Br are good oxidizing agents. Compounds within the high oxidation states (example oxides and halides) are potentially oxidizing, those within low oxidation states (example hydrides) reducing. Oxidizing power raises with group number, and reducing power respectively declines. The trends down every group are dominated through bond strength changes. Among periods 2 and 3 bonds to hydrogen turn into weaker (and so hydrides become more reducing and the elements less oxidizing) where bonds to halogens and oxygen turn into stronger (and thats why oxides and halides become less oxidizing). Compounds of As^V, Se^VI and Br^VII within period 4 are more strongly oxidizing than subsequent ones in periods 3 or 5. This alternation influence can be associated to irregular trends in ionization energies, related with the way that electron shells are filled in the periodic table.