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Limitations of Mendeleev's Periodic Table

Mendeleev arranged 63 elements known at that time in the periodic table. According to Mendeleev “the properties of the elements are a periodic function of their atomic masses.” The table consists of eight vertical column called ‘groups’ and horizontal rows called ‘periods’
Limitations of mendeleev’s classification :
(i) He could not assign a correct position of hydrogen in his periodic table, as the properties of hydrogen resembles both with alkali metals as well as with halogens.
(ii) The isotopes of the same element will be given different position if atomic number is taken as basis, which will disturb the symmetry of the periodic table.
(iii) The atomic masses do not increases in a regular manner in going from one elements to the next.
So it was not possible to predict how many elements could be discovered between two elements.

Comments

  1. Replies
    1. Thanks Sir but I want the smallest papers link...of CBSE questions paper...

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  2. The (ii) is wrong
    It should be atomic mass not atomic number.

    ReplyDelete
  3. It is really useful
    Thank you

    ReplyDelete
  4. Thank you it makes easy to understand

    ReplyDelete
    Replies
    1. Not so good but helpfull

      Delete
    2. Not so good but helpfull

      Delete
  5. In the second point, it is atomic mass and not atomic no.

    ReplyDelete
    Replies
    1. Actually that is right. What I was suggesting is that if we took atomic number as reference, then the isotopes will have a different position which can not be done with taking atomic mass as a reference.

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  6. I think in (ii) there will be atomic mass not atomic no. Please clerify me

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  7. Very good explanations it is ...thank you

    ReplyDelete
  8. Thanks for giving us nice concept

    ReplyDelete
  9. In (ii) it is atomic mass not atomic number and overall answer is good and easy so i will give this anwer 4/5 one mark cut for point(ii)

    ReplyDelete

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