Chemistry · Periodic Classification Of Properties · NEET
John Newlands (1865) put all known elements in a row, from lightest atomic weight to heaviest. He saw that the 8th element was like the 1st, the 9th like the 2nd, and so on. This is the same as a music scale, where the 8th note sounds like the 1st note (an octave). So he called it the Law of Octaves. Example: Lithium (1st), then the 8th element Sodium, both are soft, reactive metals.
It worked only for the light (small) elements up to calcium. After calcium, the pattern broke down. As heavier elements were discovered, the '8th = similar' rule stopped matching. Also, Newlands forced elements into fixed slots and even put two different elements in the same box, which mixed up unlike elements. So the law was too rigid and could not fit all elements.
It held true only up to calcium (Ca). This is a very common one-line NEET fact. Beyond calcium the repetition of properties every eighth element no longer worked, so the law was limited to the lighter elements.
The English chemist John Alexander Newlands proposed it in 1865. His idea was not accepted by scientists at that time. But much later, in 1887, the Royal Society of London honoured his work with the Davy Medal, because the octave idea was an early step toward the periodic table.
Dobereiner grouped elements in threes (triads), where the middle element's atomic weight is about the average of the other two. Newlands arranged ALL elements in one long series and looked for repetition every eighth element. So triads = small groups of 3; octaves = a repeating pattern of 8 across the whole list. Newlands came after Dobereiner and was a step closer to Mendeleev's table.
In Western music there are 7 basic notes (Do Re Mi Fa Sol La Ti), and the 8th note starts the pattern again at a higher pitch, sounding like the 1st. That repeat is called an octave. Newlands noticed the same 'every 8th one repeats' pattern in elements, so he borrowed the music word. It does not mean elements make sound; it is just a comparison.
Try the real previous-year questions from this chapter — each with the answer and a full solution.
1865, by John Alexander Newlands.
The Davy Medal, given by the Royal Society of London in 1887, long after his idea was first ignored.
On the basis of increasing atomic weight (atomic mass), not atomic number. Atomic number was discovered much later by Moseley.
Lithium is the first, and the eighth element in Newlands' arrangement, Sodium, shows similar properties — both are soft, light, very reactive alkali metals.
No. Scientists of that time rejected and even mocked it. It was only appreciated later as an early clue to periodicity.
