Question

There are -------- periods in Mendeleev's periodic table.

Answer 1

Mendeleev periodic table :

• In Mendeleev, periodic table elements were arranged based on increasing atomic mass. During Mendeleev, only 63 elements were known so after studying the properties of elements he arranged them into vertical columns called groups and horizontal rows are called periods.
• During arrangement, there were seven periods and eight groups in Mendeleev's periodic table.

Hence there are seven periods in Mendeleev's periodic table.