Merits and demerits of mendleevs periodic table
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merits
he was the first to classify all known elements at that time
he had left some blank spaces for the elements that were yet to be discovered. also he predicted properties of these elements before their discovery
demerits
hydrogen resembles alkali metals as well as halogens
elements with higher atomicass were placed before elements of lower atomic mass example cobalt was placed before nickel
he was the first to classify all known elements at that time
he had left some blank spaces for the elements that were yet to be discovered. also he predicted properties of these elements before their discovery
demerits
hydrogen resembles alkali metals as well as halogens
elements with higher atomicass were placed before elements of lower atomic mass example cobalt was placed before nickel
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Merits of Mendeleev's periodic table:
》Mendeleev had to place an element with a slightly greater atomic mass before an element with a slightly lower atomic mass.The sequence was inverted so that elements with similar properties could be grouped together.
》Mendeleev left some gaps in his Periodic table. Instead of looking upon these gaps as defects, Mendeleev boldly predicted the existence of some elements that had not been discovered at that time. Mendeleev named them by prefixing a Sanskrit numeral , Eka(one) to the name of preceeding element in the same group.
》One of the strengths of Mendeleev's Periodic Table was that, when noble gases like Helium (He), Neon (Ne), and Argon ( Ar) were discovered , they could be placed in a new group without disturbing the existing order.
Demerits of Mendeleev's Periodic Table:
》 He could not assign a correct position to hydrogen in his table.
》 Isotopes of all elements posed a challenge to Mendeleev's Periodic law.
》 Another problem was that the atomic masses do not increase in a regular manner in going from one element to the next.
》Mendeleev had to place an element with a slightly greater atomic mass before an element with a slightly lower atomic mass.The sequence was inverted so that elements with similar properties could be grouped together.
》Mendeleev left some gaps in his Periodic table. Instead of looking upon these gaps as defects, Mendeleev boldly predicted the existence of some elements that had not been discovered at that time. Mendeleev named them by prefixing a Sanskrit numeral , Eka(one) to the name of preceeding element in the same group.
》One of the strengths of Mendeleev's Periodic Table was that, when noble gases like Helium (He), Neon (Ne), and Argon ( Ar) were discovered , they could be placed in a new group without disturbing the existing order.
Demerits of Mendeleev's Periodic Table:
》 He could not assign a correct position to hydrogen in his table.
》 Isotopes of all elements posed a challenge to Mendeleev's Periodic law.
》 Another problem was that the atomic masses do not increase in a regular manner in going from one element to the next.
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