Question

how many periods and groups are there in mendeleev periodic table

Answer 1

It is seven period and eight groups

Answer 2

Periodic table is the organised way of arranging the chemical elements present in our environment.

The modern periodic table has been derived from various early models of periodic tables.

Similarly,Mendeleev's periodic table is one of the most popular early adaptions of the periodic table which have only eight groups and seven periods because many elements were not invented at that time.