Question

what were the notable contributions made by Dobereiner, Newland and Mendeleev towards the development of the periodic table ? Why did their laws fail ?

Answer 1

Answer:

• advantages

1. dobereiner triads: advantages it is made chemist took look into the elements as groups of elements having physical and chemical properties
2. newlands law of octaves::first attempt to classify the elements on their basic concept of atomic masses
3. Mendeleevs periodic table:it could predict the errors in atomic masses of certain elements and added the concept of periods and groups

• disadvantages

1. dobereiner traids: he could identify only three triads from the elements know at that time
2. newlands law:it was applicable till calcium only
3. mendeleev:did not provide the clear structure of atom and could not able to explain the concept of isotopes