Question

The periodic table is composed of _________ and __________.

A. periods and rows
B. groups and columns
C. molecules and groups
D. groups and periods

Answer 1

D. groups and periods

Step-by-step explanation:

In groups the elements have the same electronic configuration in the last electronic shell and we expect that they will have similar chemical properties.

In periods the electronic configuration is increasing with one electron as we proceed from left to right and so the chemical properties will vary significantly.