Question

What were the limitations of Newland’s law of octaves?

Answer 1

Hint: Newlands proposed his periodic table on the basis of the atomic masses of elements and thus, had a many dissimilarity in the arrangements of elements which led to its failure. Now, write its limitations.

Complete step by step solution:
- Newlands, a British scientist, arranged the 62 elements present in his time in the increasing order of their relative atomic masses( average mass of the atoms of an element) and stated that the properties of every eighth element is similar to that go the first one element and on , thus, this observation he proposed the Newlands law of octaves. E.g. The eighth element from lithium is potassium and thus, according to his arrangement their properties are similar to one another.
NEWLANDS PERIODIC TABLE

H	Li	Ga	B	C	N	O
F	Na	Mg	Al	Si	P	S
Cl	K	Ca	Cr	It	Mn	Fe
Co, Ni	Cu	Zn	Y	In	As	Se
Br	Rb	Sr	Ce, La	Zr	Di, Mo	Ro, Ru
Pd	Ag	Cd	U	Sn	Sb	Te
I	Cs	Ba, V	Ta	W	Nb	Au
Pt, Ir	Tl	Pb	Th	Hg	Bi	Cs

- But his proposed method was not much appropriate to classify all the elements and their properties and was not applicable to all the elements and led to the failure of the newland law of octaves.
- Major Limitations of his law are as under:
- His law was applicable only to the lighter elements i.e. the elements with the atomic masses of 40 a.m.u. only up to. It means only up to calcium and after that the properties of every eighth element is not similar with the first one element.
- He put iron (Fe) which has some properties similar to cobalt and nickel was placed in different groups along with oxygen and Sulphur which are non-metals.
- In his periodic table, several elements were put together which had not similar properties with one another but still they were grouped together. E.g. halogens have different properties and are placed together in the group of cobalt, nickel and platinum which are metals.
- There were many elements which in spite of not having much similarity with one another were placed according to the Newlands law of octaves. E.g. cobalt and nickel do not have much similarity placed in the same Newlands criteria.
-Further, the news discovered elements do not fit into the criteria as proposed by the Newlands.
-Thus, all the reasons led to the failure of the Newlands law of octave and his proposed periodic table was not accepted by other scientists.

Note: This law holds good only for the elements up to calcium and was not applicable for new discovered elements so it was discarded and the modern periodic table came into light in which the elements are arranged on the increasing of their atomic weights.