Polyvalent elements are elements in the d-block(transition metals) and they can take on multiple charges to have either 2 or 8 valence electrons. Groups determine the charge (or electron on outermost shell). Transition metals have no group so their charges are undefined.

What are polyvalent ions?

Polyvalent ion refers to when, the atom in an ion have a valency of more than one. i.e when the valency of the ion is greater than one. For example: O2− ion is a polyvalent ion as it has a valency of more than one, but it is a monoatomic ion.

What is a multivalent metal example?

Iron is a multivalent metal; therefore, it can form bonds with oxygen in more than one proportion. Fe2O3 and FeO are both legitimate formulas for the compounds formed by these two elements.