Question

In Mendeleev's periodic table, the vertical columns are called _______ and the horizontal rows are called ________

• A. groups
• B. periods

Answer 1

Mendeleev's Periodic Table:

• Mendeleev's periodic table is the table in which the elements are arranged based on their fundamental properties i.e. the atomic mass, and similar chemical properties.
• Therefore were $63$ elements known at that time.
• $63$ elements were arranged in the increasing order of their atomic masses and found that the elements with similar chemical properties occur at regular intervals.
• The periodic law states that the properties of elements are a periodic function of their atomic masses.

Groups and Periods

• Mendeleev observed that elements with similar properties fall in the same vertical column.
• The vertical columns are called groups and horizontal rows are called periods.
• There are eight groups and seven periods present in Mendeleev's periodic table.

Therefore, in Mendeleev's periodic table, the vertical columns are called groups, and the horizontal rows are called periods