• Some elements do not fit to his classification that was based on the atomic weights. For example, cobalt was placed before nickel, tellurium before iodine etc.
• He violated his periodic law at certain places to assign the correct position to elements on the basis of their properties.
• The position of hydrogen was not defined correctly as it resembled few characteristics of alkali metals and few of halogens.
• Position of isotopes would be different according to Mendeleev’s periodic table.
• No separate positions were given to lanthanoids and actinoids.
• Position of group VIII elements was not justified.
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