Newland's Classification

In 1863 John Newland, a London industrial chemist proposed NEWLAND'S LAW OF OCTAVE, which states that:

NEWLAND'S LAW OF OCTAVE, which states that:

"If elements are arranged in the order of increasing atomic masses, the eighth element starting from a given one, has similar properties as first one i.e. its properties are a kind of repetition of the first, like the eighth note in an octave of music."          

Table 4.2 octave law

Element

Li

Be

B

C

N

O

F

Atomic Mass

7

9

      11

12

14

16

19

Element

Na

Mg

     Al

Si

P

S

Cl

Atomic Mass

23

24

    27

28

31

32

35.5

Element

K

Ca

 

 

 

 

 

Atomic Mass

39

40

 

 

 

 

 

                

 

 

 

 

For example, Na is eighth element from Li and has similar properties, Mg is eighth element from Be and has similar properties, etc.

This arrangement of elements for the first time brought to light the existence of PERIODICITY i.e. recurrence of chemical and physical properties at regular interval and provided a great idea towards the development of modern periodic table. This law failed because it held good for the first sixteen elements but did not work after seventeenth element. Moreover hydrogen was not included in this sequence.

4.1.3 Lother Meyer's Classification:

Julius Lother Meyer, a German scientist, in December 1869 published a periodic table, in which the then known 56 elements were arranged on the basis of their atomic masses in nine vertical columns or groups from I to IX. But he laid down emphasis on the physical properties of elements.

Lother Meyer calculated one atomic volume of elements. The atomic volume of an element is the volume which would be occupied by 1 gram atomic weight (1 mole) of atoms of element if it were a solid.

 

Atomic volume         =       Gram atomic weight

                                                          Density

In order to emphasize the concept of periodicity, he plotted a graph between atomic volumes of elements against their increasing atomic masses.

He observed that the elements with similar properties occupy similar positions on the curve. For example, the highly reactive alkali metals (Li, Na, K, Rb, Cs) occupy the peaks there by showing that these elements have largest atomic volumes. The regular spacing of the highest points confirms the idea of periodicity, suggested by Newland.


 

 
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