Elements that can form ions with more than one charge are called transition metals. These elements are located in the d-block of the periodic table, which runs from group 3 to 12.

Here's why transition metals form multiple ions:

* Variable Oxidation States: Transition metals have multiple electrons in their d-orbitals, which can be readily lost to form ions. The number of electrons lost can vary, leading to different oxidation states and thus different charges on the ion.

* Electron Configuration: The d-orbitals are relatively close in energy, allowing for the loss of electrons from different energy levels. This flexibility gives rise to multiple possible ionic charges.

Examples:

* Iron (Fe): Can form Fe²⁺ (ferrous) and Fe³⁺ (ferric) ions.

* Copper (Cu): Can form Cu⁺ (cuprous) and Cu²⁺ (cupric) ions.

* Manganese (Mn): Can form Mn²⁺, Mn³⁺, Mn⁴⁺, Mn⁶⁺, and Mn⁷⁺ ions.

Note: While transition metals are the primary group of elements that form multiple ions, some non-metals can also exhibit variable oxidation states and form ions with different charges. For example, phosphorus (P) can form P³⁻, P⁵⁺, and P³⁺ ions.