DRAWBACKS OF DOBEREINER LAW OF TRIADS
DRAWBACKS OF NEWLANDS LAW OF OCTAVE
DRAWBACKS OF MENDELLEnvironmental Sciences PERIODIC TABLE
Answers
Drawback of Dobereiner's triads:
Dobereiner could identify only three triads. He was not able to prepare triads of all the known elements
All the known elements could not be arranged in the form of triads.
For very low mass or for very high mass elements, the law was not holding good. Take the example of F, Cl, Br. Atomic mass of Cl is not an arithmetic mean of atomic masses of F and Br.
Limitations of Newland's Law of Octaves:
Newland could arrange elements only up to calcium, out of the total 56 elements known.
After calcium, every eighth element did not possess properties similar to that of the first.
Only 56 elements were known at the time of Newlands, but later several elements were discovered.
In order to fit the existing element arrangement, Newlands placed two elements in the same position which differed in their properties.
For example Iron, an element which resembles cobalt and nickel in its properties is placed far away from these elements.
The periodic table did not include inert gases because they were not discovered then.
DRAWBACKS OF MENDELL:
The factors (genes) determine the organism's traits, and are inherited from its parents. As the pair of chromosomes separate, each gamete only receives one of each factor. This Mendel called the Law of segregation. Mendel also noted that versions of a gene could be either dominant or recessive.
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