Question

Who were the three persons who tried to arrange all the elements in periodic table but failed. List the names and of those three persons and write the limitations of each...​

Answer 1

William prout,John Wolfgang döberenier,John newlands

Answer 2

HERE IS YOUR ANSWER:

• Dobereiner’s Triads :-

A German chemist and professor, Dobereiner’s attempt at classification of elements are generally considered the first recorded attempt. He identified elements with similar properties and grouped them into groups of three, hence the name “triads”. He realized when you arrange these three elements according to their atomic weight, the atomic weight of the second element was roughly the average of the atomic weights of the first and third element.

Limitation of dobereiner:

However, Dobereiner soon found out that this was not uniform across all elements, and so this system had very short-lived and limited success.

• Newlands law of octaves

Newland arranged the known elements in increasing order of atomic mass. He found that the every eighth element had properties similar to that of first one. He compared it to the octaves found in music and thus it is called Newland's law of octaves.

Limitation of Newlands:

The major limitations of Newlands' law of octaves were : (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.

• Dmitri Mendeleev

Like many scientists working at the end of the 19th-century the Russian chemist Dmitri Mendeleev (1834-1907) was looking for ways to organise the known elements. Mendeleev published his first periodic table of the elements in 1869.Mendeleev arranged the elements in order of increasing relative atomic mass. When he did this he noted that the chemical properties of the elements and their compounds showed a periodic trend. He then arranged the elements by putting those with similar properties below each other into groups.

Limitation of Mendeleev:

Position of Hydrogen => Position of hydrogen in the perodic table is Uncertain , Because hydrogen is placed in 1 A group with Alkali metals .

Position of isotopes => isotopes haven't been given separate place in perodic table .

HOPE IT HELPS YOU...