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Law of Octaves

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In 1829, John Do bringer noted chemical similarities in several groups of three elements and placed these elements into what he called triads. In 1864, John Newlands saw a connection between the chemical properties of elements and their atomic masses. He stated that if the known elements, beginning with lithium are arranged in order of increasing mass, the eighth element will have properties similar to the first element, the ninth similar to the second, the tenth similar to the third and so on.


Newlands called his relationship the law of octaves, comparing the elements to the notes in a musical scale. Newlands tried to force all the known elements to fit into his octaves, but many of the heavier elements, when discovered did not fit into his patterns.

Octaves Definition

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Law of Octaves Definition

If the elements are arranged in order of increasing atomic weight the eighth element starting from a given one is a kind of repetition of the first like the eighth note in an octave of music.

Li
Be
B
C
N
O
F
Na
Mg
Al
7
9
11
12
14
16
19
23
24
27
Si
P
S
Cl
K
Ca
     
28
31
32
35.5
39
40      

Starting from Lithium the eighth element is sodium so the properties of lithium and sodium should be similar. Again the eight element from sodium id potassium.

John Newlands Law of Octaves

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In 1864, Newlands arranged elements in ascending order of atomic weights. He wrote "the eighth element starting from a given one is a kind of repetition of the firs, like the eight notes of an octave of music". He called this relationship the Law of Octaves.

John Newland

Newland noticed a pattern based on two aspects of elements, their chemical reactivity and their atomic masses. When elements were arranged in order of increasing atomic mass, a repetition of properties appeared after every eight elements. Elements in the same columns shared similar chemical properties. This represent the first attempt to organize the elements in a grid arrangement.

Newlands thought that rather like music where one note resembles the note eight places or an octave away.

Unfortunately Newland's Law of Octaves only worked for the first 16 elements because
  1. Some of the atomic masses he used were inaccurate.
  2. At that time, some elements had not been discovered. When they were discovered it was found that there was no room for then in his series, for example noble gases.

John Newlands Periodic Table

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John Newlands had the idea of arranging the elements in order of their relative atomic masses. The element hydrogen has the lightest atoms. The masses of other atoms are compared with that of a hydrogen atom. One atom of carbon is 12 times as heavy as one atom of hydrogen so we say that the relative atomic mass of carbon is 12. One atom of calcium is 40 times as heavy as one atom of hydrogen, so we say that the relative atomic mass of calcium is 40.

John Newlands Periodic Table

In Newlands time 55 elements were known. Newlands found that similar elements appeared at regular intervals in the list. The arrangement of elements according to Newland is shown below.

1
2
3
4
5
6
7
H
Li
Be
B
C
N
O
F
Na
Mg Al
Si
P
S
Cl
K
Ca
Cr
Ti
Mn Fe
Co, Ni
Cu
Zn
Y
In
As
Se
Br
Rb
Sr
Ce, La Zr
Bi, Mo
Rh, Ru
Pd
Ag
Cd
U Sn
Sb
Te

  1. The same properties were repeated at every eighth element in his arrangement. This pattern was similar to the octave notes in music.
  2. The classification of elements by john Newlands was not successful because his law of octaves was obeyed by the first 17 elements only (from H to Ca).
  3. However his contribution was important because he was the first chemist to show the existence of a periodic pattern in the properties of the elements.
  4. The periodic repetition of the properties of the elements was used as a basis for further development of the periodic table.

Octave Examples

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In 1864 Newland arranged the elements in the order of increasing atomic masses and noticed that the eighth element, starting from a given one, is a kind of repetition of the first like the eighth note in an octave of music. Newland named this generalization the law of octaves due to its similarity to the musical scale.

Although Newlands law of octaves met with ridicule nevertheless Newlands was the first to publish a list of the elements in the order of increasing atomic masses. The following arrangement illustrates the law of octaves.

Li
Be
B
C
N
O
F
Na
Mg Al
Si
P
S
Cl
K Ca

However law of octaves also could not be applied beyond calcium. Moreover, with the discovery of noble gases, the eighth element no longer remains a similar element.