Final answer:
The elements with similar properties are located in the same group on the periodic table, as they share the same number of valence electrons.
Step-by-step explanation:
Elements in the same group have similar properties. This occurs because elements in a group have the same number of valence electrons, which leads to similarities in their chemical reactivities. For example, alkali metals, which make up Group 1, all have one valence electron and are highly reactive. Group 17 contains halogens, and elements within this group are known for their reactivity and ability to form salts. Lastly, Group 18 is made up of noble gases, which are known for their lack of reactivity due to having full energy orbitals.