(A)State Newlands Law Of Octaves
(B)State Mendeleev'S Law Of Periodic Table
Answers
(a) Limitations of Newlands' law of octaves:
→ It was not applicable throughout the arrangements. It was applicable up to calcium only. The properties of the elements listed after calcium showed no resemblance to the properties of the elements above them.
→ Those elements that were discovered after Newlands' octaves did not follow the law of octaves.
→ The position of cobalt and nickel in the group of the elements (F, Cl) of different properties could not be explained.
→ Placing of iron far away from cobalt and nickel, which have similar properties as iron, could also not be explained.
(b) Various anomalies of Mendeleev’s Periodic Table removed as follows in the Modern Periodic Table:
→ Elements are arranged in the increasing order of their atomic number in Modern Periodic Table, thus there was no need for keeping more than one element in one slot.
→ In Modern Periodic Table there was no problem of the place of isotopes, as isotopes have same atomic mass with different atomic numbers.
→ Elements having same valence electron are kept in same group.
→ Elements having same number of shells were put under the same period.
→ Position of hydrogen became clarified in as it is kept in the group with the elements of same valence electrons.
Answer:
A)Newland's Law of Octaves. In the year 1864, the British chemist JohnNewlands attempted the 62 elements known at that time. ... The law of octaves states that every eighth element has similar properties when the elements are arranged in the increasing order of their atomic masses.
B)Mendeleev's periodic law stated that " properties of elements are aperiodic function of their atomic masses." C) hydrogen resembles both alkali metals and halogens. ... Hence it can be placed in group 1 or 17. Thus position of hydrogen could not be fixed.