Question

what is the main reason that elements in the same group of the periodic table have similar chemical properties? they have the same number of valence electrons. they have the same number of protons. they have the same atomic mass. they have the same number of neutrons.

Explanation:

Valence electrons are responsible for an element's chemical behavior. Elements in the same group have the same number of valence electrons, leading to similar chemical properties. Protons determine the element's identity, atomic mass and neutron - number vary among isotopes and are not related to group - based chemical similarity.

Answer:

They have the same number of valence electrons.