Name: Mendeleev's Periodic Table
Uploaded: 2019-07-19
Duration: 6 min 58 s
Description: Shortcomings of past periodic table classifications paved the way for a scientist named Dmitri Mendeleev to work on the classification of elements. Watch thi...

Question

The modern periodic table has been evolved through the early attempts of Dobereiner, Newland and Mendeleev. List one advantage and one limitation of all the three attempts.

Accepted Answer

1. Dobereiner:
Advantage: Dobereiner give the concept of Dobereiner triads. He placed three elements having similar properties in the same group. These elements were arranged in increasing order of atomic mass and the mass of middle element was the average of the other two.
Limitation: Only 4 triads were identified by him. He also failed to group nitrogen, phosphorus and arsenic because atomic mass of phosphorus is not the average of other two.

2. Newland:
Advantages: Newland arranged the elements in horizontal rows in order of increasing atomic mass such that the property of every 8th element was similar to that of 1st element.
Limitation: His arrangement was only applicable to lighter elements having atomic masses upto 40.

3. Mendeleev:
Advantage: He states that the properties of elements are the periodic functions of their atomic masses. He left some spaces in the periodic table for the discovery of new elements.
Limitation: Position of hydrogen and isotopes were not justified in his periodic table.

The modern periodic table has been evolved through the early attempts of Dobereiner, Newland and Mendeleev. List one advantage and one limitation of all the three attempts.

Important Questions on Periodic Classification of Elements

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