Question

question 20 of 25
why do elements within a period of the periodic table have different properties?
a. they have different numbers of valence electrons.
b. they have different combinations of protons and neutrons.
c. some are metals and some are nonmetals.
d. they have different arrangements of core electrons.

Explanation:

Valence electrons determine an element's chemical properties. Elements in the same period have the same number of electron - shells but different numbers of valence electrons, leading to different properties.

Answer:

A. They have different numbers of valence electrons.