The lowest oxides of transition metals are generally basic, while the highest oxides are acidic or a

Question

The lowest oxides of transition metals are generally basic, while the highest oxides are acidic or amphoteric. Which of the following best explains this trend?

Professor PC Thomas Classes · Answer

As the oxidation state increases, the charge density on the metal ion increases. According to Fajan's rules, this increases its polarizing power, leading to a more covalent M-O bond. Covalent oxides tend to be acidic, while ionic oxides (lower oxidation states) are basic.