Question

Differentiate between arrangement of elements in mendeleevs periodic table and modern periodic table

Answer 1

Mendeleev’s Periodic Table

The elements were arranged according to increased atomic masses.

Position of isotopes was not justified.

Position of hydrogen was not justified because it resembles both with Alkali metals and Halogens.

Modern Periodic Table

The elements were arranged according to increased atomic numbers.

There was no problem in the placing of isotopes.

Hydrogen has been given a unique position due to its resemblance with Alkali metals and Halogens.

Answer 2

MENDELEEV'S PERIODIC TABLE:
-ELEMENTS WERE ARRANGED IN THE ORDER OF INCREASING ATOMIC WEIGHT.
-GAPS WERE LEFT BY MENDELEEV FOR THE LATER DISCOVERED ELEMENTS.
-TRANSITION ELEMENTS WERE LISTED WITH THE OTHER ELEMENTS.

MODERN PERIODIC TABLE:
-ELEMENTS WERE ARRANGED IN THE ORDER OF INCREASING ATOMIC NUMBERS.
-NO GAPS WERE LEFT FOR THE LATER DISCOVERED ELEMENTS.
-TRANSITION ELEMENTS WERE LISTED IN A SEPARATE BLOCK.