Question

differentiate between Mendeleev's periodic table and modern periodic table....

Answer 1

Difference 1 :

• Mendeleev's periodic table was based on the increasing order of the atomic mass of the elements.
• Whereas modern periodic table is based on the increasing order of the atomic number not atomic mass.

Difference 2 :

• Place of hydrogen was not fixed in Mendeleev's periodic table.
• Place of hydrogen is fixed in periodic table.

Difference 3 :

• Although the Mendeleev's periodic table was based on the increasing order of the atomic mass, there were few elements with large atomic mass which were placed just before an elements having less atomic number with them.
• This thing is resolved in modern periodic table.

Answer 2

The main differences are:

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 presently 118 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.