Merits and Demerits of Mendeleev's Periodic table | Chemistry

Merits of Mendeleev's Periodic Table (a) Mendeleev could not assign a correct position to hydrogen in the periodic table as hydrogen resembles alkali metals as well as halogens. (b) Isotopes had to be given the same position in the periodic table though isotopes of the same elements have different atomic masses. (c) It was observed that at certain places, an element of higher atomic mass Cobalt (Co=58.93) has been placed before an element of lower atomic mass Nickel (Ni = 58.71). (d) Some elements placed in the same subgroup vary in their properties. Manganese is placed with halogens which totally differ in the properties. Demerits of Mendeleev's Periodic Table (a) Mendeleev arranged elements in the ascending order of their atomic masses. There was no fixed position for hydrogen in his periodic table, as it resembled alkali metals as well as halogens. (b) Elements of higher atomic mass were placed before elements of lower atomic mass. Cobalt with atomic mass 58.93 was placed before nickel with atomic mass 58.71. (c) Elements having different properties were placed in the same subgroup as manganese (Mn) was placed with halogens which had totally different properties #periodictable #Mendeleev #mendeleevperiodictable For more videos, online classes, 24X7 Doubts solving and Mock tests, Visit Toppr - The better learning app. #BetterLearning on the Toppr app, download now Google Play: http://bit.ly/2vRBqcb App Store: http://apple.co/2vpRAr9 Website: https://www.toppr.com/ Download Doubts on Chat App: Android Play Store: http://bit.ly/2B6w7oy iOS App Store: http://apple.co/2ziAA75 Facebook: https://www.facebook.com/beingToppr Twitter: https://twitter.com/mytoppr Instagram: https://instagram.com/mytoppr LinkedIn: https://www.linkedin.com/company/toppr-com/

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