Question

<!--td {border: 1px solid #ccc;}br {mso-data-placement:same-cell;}--> Compare and contrast the arrangement of elements in Mendeleev’s Periodic Table and the Modern Periodic Table.

Answer 1

<!--td {border: 1px solid #ccc;}br {mso-data-placement:same-cell;}--> Mendeleev’s Periodic Table:
* Elements are arranged in the increasing order of their atomic masses.
* There are 8 groups
* Each groups are subdivided into sub group ‘a’ and ‘b’
* Groups for Noble gas was not present as noble gases were not discovered by that time
* There was no place for isotopes.

Modern Periodic Table
* Elements are arranged in the increasing order of their atomic numbers.
* There are 18 groups
* Groups are not subdivided into sub-groups.
* A separate group is meant for noble gases
* This problem has been rectified as slots are determined according to atomic number.