Question

five major differences between Mendeleev periodic table and modern periodic table.

Answer 1

Mendeleev's periodic tableModern periodic table

Mendeleev's periodic table is based on atomic mass

Modern periodic table is based on atomic number

Mendaleev's periodic table contains about 66 elements.

Modern periodic table contains about 112 elements

In Mendeleev's  periodic table there were gaps for undiscovered elements.

Modern periodic table maintains uniformity.

In Mendeleev's periodic table noble gases were not placed (as they are not discovered at that time).In Modern periodic table noble gases in a seperate group named as group-18.In Mendeleev's periodic table transition elements included with other elementsIn Modern periodic table transition elements  placed in separate block.

Answer 2

Answer:

• Mendeleev's periodic table

1. elements are arranged in increasing order of their atomic masses.
2. It is not divided into any blocks.
3. There are 8 groups.
4. Isotopes could not be placed properly.

• Modern periodic table

1. Elements are arranged in increasing order of their atomic numbers.
2. It is divided into four blocks, namely s-block,p-block,d-block and f-block.
3. There are 18 groups.
4. Isotopes occupy the same position as the element.

Hope you understood mate!!!