use the drop - down menu to complete the statement. atoms of elements in the same group have the same number…

Brief Explanations:

Elements in the same group of the periodic table have the same number of valence electrons. Valence electrons are responsible for an element's chemical behavior, so elements with the same number of them have similar chemical properties. Neutrons affect mass - number and isotopic nature, not chemical properties directly. Protons determine the element's identity but not similarity within a group in terms of chemical behavior like valence electrons do.

Answer:

valence electrons