Write the limitations of Mendeleeff's periodic table.

1.	Write the limitations of Mendeleeff's periodic table.
Answer» (1) Anomalous pair of elements : Certain elements of highest atomic weights precede those with lower atomic weights. Ex : Tellurium (At.wt. 127.6) precedes 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 : (1) Alkali metals like Li, Na, K, etc. of IA group have little resemblance with image metal like Cu, Ag, Au of IB group. (2) Cl is of VIIA group and 'Mn' is of VIIB. But chlorine is a non-metal where Mn is a metal.

Answer»

(1) Anomalous pair of elements : Certain elements of highest atomic weights precede those with lower atomic weights.

Ex : Tellurium (At.wt. 127.6) precedes 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 :

(1) Alkali metals like Li, Na, K, etc. of IA group have little resemblance with image metal like Cu, Ag, Au of IB group.

(2) Cl is of VIIA group and 'Mn' is of VIIB. But chlorine is a non-metal where Mn is a metal.

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