Study the data of the following three categories A, B and C. (i) from the given three categories A, B and C, pick the one which forms Dobereiner.s Triads. (ii) Why did Mendeleev placed elements of category A, B and C in three different groups? (iii) Is Newland law of octaves applicable to all the three categories? Give reason to justify your answer.

Study the data of the following three categories A, B and C. (i) fr

1.	Study the data of the following three categories A, B and C. (i) from the given three categories A, B and C, pick the one which forms Dobereiner.s Triads. (ii) Why did Mendeleev placed elements of category A, B and C in three different groups? (iii) Is Newland law of octaves applicable to all the three categories? Give reason to justify your answer.
Answer» Solution :(i) Category A forms triad, `(7+39)//2=23.` (ii) Mendeleev based his periodic table on the law that properties of elements are periodic function of atomic MASSES. He sorted out the elements with similar properties and grouped them together. Li, Na and K has similar properties, they were grouped together. N, P and As had similar properties they were grouped together. Similarly, B, Al and Ga has similar properties, they were grouped together. (iii) Newlands law of OCTAVES was APPLICABLE upto calcium. After calcium, every eighthelement did not have properties similar to the first. Therefore we can say that elements of category A FOLLOWS Newlands law.