Question

question 18 of 25
why do elements within a period of the periodic table have different properties?
a. some are metals and some are nonmetals.
b. they have different numbers of valence electrons.
c. they have different arrangements of core electrons.
d. they have different combinations of protons and neutrons.

Explanation:

The chemical and physical properties of elements are mainly determined by the number of valence electrons. Elements in the same period have the same number of electron - shells but different numbers of valence electrons, which leads to different properties.

Answer:

B. They have different numbers of valence electrons.