Newlands’ Law of Octaves (JEE/NEET Concepts)
Proposed by John Alexander Reina Newlands (1864), this was another early attempt to classify elements.
🔹 What is Newlands’ Law of Octaves?
Statement:
When elements are arranged in increasing order of atomic mass,
every 8th element has properties similar to the first, just like musical octaves 🎵
Why “Octaves”?
Inspired by music:
- In music, the 8th note repeats
- Similarly, in elements:
- 1st ≈ 8th
- 2nd ≈ 9th
- and so on
🔹 Example (Important for Exams)
| Element No. | Element | Similar To |
|---|---|---|
| 1 | Li | Na (8th) |
| 2 | Be | Mg |
| 3 | B | Al |
| 4 | C | Si |
| 5 | N | P |
| 6 | O | S |
| 7 | F | Cl |
Example:
- Li and Na → similar properties
- Be and Mg → similar properties
Key Features
- First to show periodicity in a systematic way
- Applicable mainly to lighter elements (up to Ca)
- Based on atomic mass
🔹 Limitations (VERY IMPORTANT )
- Worked only up to Calcium (Ca)
- No space for new elements
- Dissimilar elements grouped together:
- Co and Ni placed with F, Cl
- Ignored transition elements
- Assumed only 56 elements existed
🔹 Why Important?
- First clear attempt to show periodic repetition
- Helped in development of:
- Dmitri Mendeleev Periodic Table
Sarvan sir- Chemistry For All 