Give limitations of dobereiner's triads,newland's law of octaves and mendeleev's periodic table....
Answers
Dobereiner's Traids:
1. Dobereiner could find only three triads; . i.e total of 9 elements only.
2. However the total number of elements were more than that of those encompassed in Dobereiner's Triad.
3. Thus, Dobereiner's could not be classify most of the elements known at that time.
Newland's Law of Octaves:
1. It was capable upto calcium only.
2.Inorder to adjust the elements, he put two elements in 1 slot.
3. Elements which have distinct properties were put in the same group.
4. Elements which have similar properties were put far from each other.
Mendeleev's periodic table:
1. Position of Hydrogen => Position of hydrogen in the periodic table is Uncertain , Because hydrogen is placed in 1 A group with Alkali metals .
2. Position of isotopes => isotopes haven't been given separate place in perodic table .
3. Cause of periodicity => Mendeleev could not explain the cause of periodicity .
4. Separation of similar elements => some