Question

Give a one-word answer

Horizontal rows are known as.

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.
• Therefore, the number of electron shells around the nucleus of an atom represents its period number in the periodic table.