Question

In the modified Mendeleev’s periodic table,________ groups and ________ periods are present, whereas in modern periodic table,_____ groups and _____ periods are present.

• A. 8 groups and 7 periods
• B. 18 groups and 7 periods

Answer 1

1. Mendeleev periodic table:

Mendeleev classified elements based on the increasing atomic masses into eight groups and seven periods.

1. Modern periodic table:

Moseley classified elements based on increasing atomic number of elements into eighteen groups and seven periods.

Hence, In the modified Mendeleev's periodic table, 8 groups and 7 periods are present, whereas in modern periodic table, 18 groups and 7 periods are present, respectively.