Question

Fill in the blanks in the following statements

The horizontal rows in the periodic table are called --------.

Answer 1

Modern periodic table:

• The modern periodic table is an arrangement of all the elements known in accordance with their increasing atomic number and recurring chemical properties.
• It is a tabular display of 118 chemical elements which consists of horizontal rows called periods and vertical columns are called groups.
• All elements in a group have the same number of valance electrons, and in period elements have the same number of electron shells.
• There are seven periods and eighteen groups in the modern periodic table.

Therefore the horizontal rows in the periodic table are called periods.