Final answer:
Elements determine the charge of their ions based on their periodic table group, with alkali metals, alkaline earth metals, and halogens forming ions with characteristic charges; transition metals, however, can form ions with variable charges due to their complex electron configurations.
Step-by-step explanation:
Elements determine the charge of the ions they become based on their position in the periodic table and the number of valence electrons they possess. All ions made from alkali metals will carry a 1+ charge, while alkaline earth metals exhibit a 2+ charge.
However, transition metals are an exception to this pattern as they can have electrons in a d subshell, leading to the formation of ions with variable charges. For example, copper can form 1+ or 2+ charged ions, and iron can form ions with a 2+ or 3+ charge.