Explain the salient features and achievements of the Mendeleeff’s periodic tble.

Explanation

Mendeleeff arranged the elements in the increasesing order of their atomic weights .
Salient Features :
1) Groups and sub - groups : there are 8 vertical columns called groups . Represented by Roan numerals I to VIII . Each group is divided into two sub - group A and B . the elements present in a group and its sub - group have similar properties .
2) Periods : The horizontal rows in Mendeleeff's table are called periods' . There are 7 periods , denoted by Arab numerals 1 to 7 . A period comprises the entire range of elements after which properties of missing elements : Bassed on the arrangement of the spaces at the appropriate places in the table . He named those elements tentatively by adding the preflx'eka' to the element immediately above the each empty space . Ex : Eka - boron , eka - aluminium eka - silicon were close to the observed properties of Scandium , Galium and Germanium Eka - silicon were close to the observed peroperties of scandium , Galium and germanium respectively which were discovered later .
4) Correction of atomic weight : The correct placement of elements in Mendeleeff's periodic table helped in correcting the atomic masses of some elements like beryllium Indium Gold .
5) Anomalous series series : Some anomalous series of elements like "Te 'and 'T' were observed in the table .The anomalous series contained elements with more atomic weight like (Te Placed before the element with less atomic weight like I .