Answer:
The elements that have the same outer electronic configuration belong to the same group (column).
Step-by-step explanation:
Periodic table is a form of classification of chemical elements. In this table, the elements are classified into seven rows and eighteen columns. The horizontal rows are called periods and the vertical columns are known as groups.
The chemical elements are arranged in the order of increasing atomic number. The elements that have the same outer electronic configuration belong to the same group. Whereas, the elements having the same number of shells belong to the same period.