write the strength and weakness of mendeleevs pT
Answers
Explanation:
When noble gases were discovered can be kept in a separate group without disturbing the existing order. Disadvantages: He couldn't allocate a correct position to hydrogen. Atomic masses didn't increase in a regular manner, so it was impossible to predict how many elements could be discovered between two elements
Answer:
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 sub group like manganese (Mn) was placed with halogens which had totally different properties