Question

The modern periodic table has been evolved through the easy attempts of doberiner , newland and Mendeleev. List one advantage and one limitation of all the three attempts

Answer 1

Explanation:

Advantages of Dobereiners triads :

It gave an idea for classification of elements.

It showed some peroidic classifications between elements.

It gave a base support for Newlands and Mendeleev to make new arrangements.

limitation of doberniars triad

Dobereiner could find only three triads; . i.e total of 9 elements only. However the total number of elements were more than that of those encompassed in Dobereiner's Triad.

Advantage of new land law of octave:-

This law helped to arrange the elements with similar properties and provided a basis for classification.

limitation:-

i) It was applicable to only lighter elements having atomic masses upto 40 u, i.e., upto calcium. After calcium, the first and the eighth element did not have similar properties.

advantage of Mendeleev periodic table :-

It could predict the existence of other elements and could predict their properties so, as to leave space in the periodic table. It could accommodate all the sixty elements discovered at that time and could accommodate the noble gases which, where discovered later.

limitation of Mendeleev periodic table :-

This is because hydrogen's characteristics are very similar to halogens and alkali metals. Other key limitations in Mendeleev periodic table were that the atomic number in the table was not shown increasing in a regular pattern and the symmetry of the table was also disturbed.

Answer 2

Advantages of three attempts:

1. when the elements were arranged in the increasing order of their atomic masses,the atomic mass of middle most element is roughly the average of other two element's atomic mass

newland

1. every eighth element shows the similar properties of the first one
2. mendeleev-properties if elements are the periodic functions of their atomic masses

Disadvantages are:

1. dobreiner - he could identify only three triads
2. newland - it was applicable only upto calcium
3. mendeleev - no fixed position for hydrogen