Question

The number of valence electrons in an atom can often be quickly determined by referencing

A. the atomic number of the element.
B. the period number on the periodic table.
C. the atomic mass of the element.
D. the group number on the periodic table

Answer 1

The number of valence electrons in an atom can often be quickly determined by referencing: the group number on the periodic table.

Answer 2

Valence electrons can quickly be determined by looking at the group a element is in.
For example all elements in group 1 have 1 valence electron

So D is the correct answer