Question

question 5 of 10
how does the periodic table indicate the number of valence electrons an element has?
a. by the row number
b. by the period number
c. by the group number of the b columns
d. by the group number of the a columns

Explanation:

In the periodic table, for main - group elements (A columns), the group number indicates the number of valence electrons. Rows and periods relate to the number of electron shells, and group numbers of B columns are not straightforward for valence - electron determination for all transition metals.

Answer:

D. By the group number of the A columns