Merits and Demerits of Mendeleev's Periodic Table Video Lecture - Class 10

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measured and demerit of Mendeleev
periodic table merit of Mendeleev
periodic table mainly was the first
scientist so successfully classified all
known elements he anticipated the
discovery of more elements and made
provision to accommodate them by leaving
blank spaces manganese periodic tables
could be successfully used to predict
the properties of undiscovered animals
for example Mendeleev predicted the
discovery and properties of ten
undiscovered gallium and named it as
acre aluminum the values of atomic
weight density
melting point valency method of
discovery and formula of oxide predicted
by mentally for eco aluminium are found
to be very close to that of gallium it
was so well structured that when noble
gases were discovered later every one of
them could be accommodated in many
leaves periodic table in a separate
group without causing any immediate
changes in the tables demerit of
Mendeleev periodic tables Mendeleev
could not assign a correct position to
hydrogen in the periodic table as
hydrogen resembles alkali as well as
halogen
isotopes of the same element have
different atomic muscle tense
each of them should have been placed at
a different position in the periodic
table but the isotope being chemically
similar had to be placed at the same
position in the periodic table at
certain places and element of higher
atomic mass was placed before an element
of lower mass so that elements with
similar properties fell in the same
group this tube goes against mainly
periodic law example cobalt with atomic
mass fifty eight point nine is placed
before nickel with atomic mass fifty
eight point seven in the fourth period
till two goes against Mendeleev periodic
law some elements placed in the same
group had different properties example
manganese which is a metal is placed
with halogen which are nonmetals having
entirely different properties
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