What are the limitations of mendeleeff's periodic table ?

Explanation

Limitations of Mendeleeff's periodic table :
1 ) Anomalous pair of elements : Certain elements of highest atomic weights preccede those with lower atomic weights .
Ex : Tellurium (AT , wt = 127 .6 ) precceds iodine (at .wt = 126.9 )
2 ) Dissimilar elements placed together : Elements with dissimilar properties were placed in same group as sub - group A and Sub - group B .
Ex : 'Cl ' is of VIIA group and 'Mn ' is of VIIB . but Chlorine is a non-metal
Rectification of problems by Modern periodic table : Moseley proposed a periodic table based on atomic numbers. this arrangement eliminated the problem of anomalous series
Ex : THough Te has more atomic weight than I .it has atomic number less by one unit when compared to I .
This long form periodic table placed the elements according to the increasing order of their atomic numbers . Hence the Dissimilar elements changed their place in group and periods .
Ex : 'Cl' falls in `3 ^(rd ) ` period VIIA group wherees 'Mn' falls in `4 ^(th) ` period VIIB group .here metals and non - metals are separated .