Question

Stste three paints of difference between mendeleev's pericdic table and madern pcrodix table.

Answer 1

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 elements In Modern periodic table transition elements placed in separate block.