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Limitations of mendeleevs

Answer» Drawbacks of Mendeleev\'s table:\tPosition of hydrogen: Hydrogen is placed in group I-A of the periodic table. However, it resembles the elements of both group I A (alkali metals) and group VII A (halogens). Therefore, the position of hydrogen in the periodic table is not clear\tMetals and non-metals: No attempt has been made to place metals and non-metals separately in it.\tLanthanoides and Actinodes: Fifteen elements are placed in one position.Group III B6th period: La + 14 lathanoide elements.(58Ce to 71Lu).7th period: Ac + 14 actinoide elements.(90Th to103Lr)Thus, lanthanoids and actinoides have not been provided separate and proper places in the Mendeleev\'s periodic table.(v) Position of isotopes: Isotopes of elements are placed in the same position in the table though according to their atomic masses they should have been placed in different positions.\tSimilar elements separated in the table: Certain elements such as copper and mercury or gold and platinum which possess similarchemical properties are placed in different groups.\tDissimilar elements placed togetherin the same group: Alkali metals such as Li, Na, K etc. (group IA) are grouped together with coinage metals such as Cu, Ag and Au (group IB) though their properties are quite different.\tNumber of elements in the periods. The presence of only 2 elements in the first period, 8 in the second and third etc. can not be explained.
No proper place to H and problem of isotipes and he also put some elements in wrong order


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