Question

Differentiate between the arrangement of elements in Mendeleev's periodic table and the modern periodic table.

Answer 1

Mendeleev’s Periodic Table	Modern Periodic Table
Mendeleev's periodic table is based on atomic mass. Elements are arranged in increasing order of their atomic masses.	Modern periodic table is based on atomic number. Elements are arranged in increasing order of their atomic numbers.
There are no separate positions for isotopes of an element as their atomic masses are different.	Separate positions are not required as they have same atomic numbers.
Some elements of higher atomic masses have been placed before elements of lower atomic masses.	No such problems occur in this table. All elements are in proper order.
Some dissimilar elements are grouped together while some similar elements are not grouped together.	All similar elements are grouped together.
Electronic configuration of an element cannot be calculated from its position.	Electronic configuration of an element can be easily calculated from its position.
Mendeleev's periodic table contains about 66 elements.	Modern periodic table contains about 112 elements.