Question

compare and contrast the arrangement of elements in mendleev periodic table and Mosley modern 100-150 words​

Answer 1

Mendeleev's periodic table

Modern periodic table

1. Elements were arranged in increasing order of atomic masses. 1. Elements are arranged in increasing order of atomic numbers.

2. There are 8 groups. 2. There are 18 groups.

3. Each group is divided into subgroups a and b. 3. Groups are not divided into subgroups.

4. The group for noble gases was not present, as noble gases were not discovered at that time. 4. A separate group, i.e. group 18 is present for noble gases.

5. There was no place for isotopes. 5. This problem was rectified, as slots are determined on the basis of atomic number.

Mendeleev's periodic table is, based on relation of properties of elements as dependent on the atomic weight of element. But Modern periodic table considers atomic number as the fundamental property that decides the properties of elements. Modern periodic table does correct defects of the Mendeleev's periodic table.