Final answer:
Metals are the group of elements that tend to form cations by losing their outer shell electrons, resulting in a positively charged ion.
Step-by-step explanation:
The group of elements that tend to form cations are the metals. Metals, particularly those from group 1 and group 2 of the periodic table, easily lose one or more electrons due to the low energy needed to remove these outer shell electrons.
This results in a positive charge as there are more protons than electrons in the ion. For instance, group 1 elements have one s electron in their outer orbit that can be easily lost, while group 2 elements have two s electrons that can be removed. Transition metals can also form cations and are capable of forming cations with multiple ionic charges, like iron forming Fe²⁺ and Fe³⁺ ions.