John Newlands: The Law of Octaves
The World Before the Periodic Table
Imagine a world where scientists knew about different elements like hydrogen, oxygen, and gold, but had no organized way to see how they were related. By the mid-1800s, about 60 elements had been discovered. Chemists were like collectors with a box of unique, unrelated treasures. They knew each element had its own personality—some were explosive metals, others were invisible gases—but the underlying pattern connecting them all was a complete mystery. Finding a way to arrange these elements logically was one of the biggest scientific puzzles of the time.
John Newlands and His Big Idea
John Alexander Reina Newlands was a British chemist born in 1837. He was fascinated by the problem of element classification. In 1864, he published a paper where he proposed a revolutionary idea. He arranged the known elements in order of increasing atomic weight1. The atomic weight is essentially the relative mass of an atom of that element.
As he listed them, he noticed something astonishing. Starting from any given element, the eighth element that followed had properties very similar to the first. This pattern reminded him of musical notes, where every eighth note is the same, just at a higher pitch—this is called an octave. He called his discovery the Law of Octaves.
A Concrete Example: Newlands' Octaves in Action
Let's look at a small part of Newlands' original table to see how his law worked. He started with the lightest known element, lithium, and numbered them in sequence.
| Element Number | Element | Octave Group | Notes on Properties |
|---|---|---|---|
| 1 | Lithium (Li) | Note 1 | A soft, reactive metal |
| 2 | Beryllium (Be) | Note 2 | A hard, light metal |
| ... (skipping to show the pattern) | ... | ... | ... |
| 8 | Sodium (Na) | Note 1 | A soft, reactive metal (very similar to Lithium) |
| 9 | Magnesium (Mg) | Note 2 | A hard, light metal (very similar to Beryllium) |
| 15 | Potassium (K) | Note 1 | Another soft, reactive metal (completing the "octave") |
In this simplified example, you can see that lithium (No. 1), sodium (No. 8), and potassium (No. 15) are all soft, silvery metals that react violently with water. They are all part of the same "family" of elements, which we now call the alkali metals. Newlands' law correctly grouped them together because they appeared at positions that were eight apart in his list.
Why Was the Law of Octaves Rejected?
Despite its cleverness, Newlands' Law of Octaves was met with harsh criticism and even ridicule from the scientific community of his time. There were several major reasons for this:
1. It Didn't Work Perfectly for Heavier Elements: The pattern of eight worked well for the lighter elements, like lithium, beryllium, and carbon. However, as scientists moved to elements with higher atomic weights, the pattern broke down. Newlands had to sometimes place two elements in the same box to force the pattern to fit, which made his table look messy and unscientific to his peers.
2. The Role of Undiscovered Elements: At the time, many elements had not yet been discovered. Newlands' rigid pattern of eight had no room for these missing pieces. For example, the noble gases2 (like helium and neon) were completely unknown. If they had been, they would have disrupted his neat rows of eight. The modern periodic table has columns of 18, not 8, and leaves gaps for undiscovered elements.
3. The "Musical" Analogy Was Mocked: Other scientists thought comparing chemistry to music was silly. One famous critic, George Carey Foster, sarcastically asked if Newlands had ever tried arranging the elements by their initial letters. This mockery discouraged many from taking his work seriously.
From Octaves to the Periodic Table
Just a few years after Newlands, the Russian chemist Dmitri Mendeleev and the German chemist Lothar Meyer independently published more successful versions of the periodic table. Like Newlands, they arranged elements by atomic weight. However, they made two crucial improvements:
1. They Left Gaps: Instead of forcing elements to fit, Mendeleev boldly left gaps in his table where he predicted undiscovered elements should be. He even predicted their properties with remarkable accuracy. When these elements (like gallium and germanium) were later discovered, it proved his table was correct.
2. They Prioritized Chemical Properties over Strict Order: Sometimes, Mendeleev would slightly violate the order of atomic weight to keep elements with similar chemical properties in the same column (group). For instance, tellurium has a higher atomic weight than iodine, but Mendeleev placed iodine after tellurium because iodine's properties are similar to fluorine and chlorine, not tellurium. This was a more flexible and chemically sound approach.
Today, we know that the repeating patterns are based on atomic number3 (the number of protons in an atom's nucleus), not atomic weight. This is the fundamental property that defines an element and creates the perfect periodicity we see in the modern table.
Common Mistakes and Important Questions
Q: Did John Newlands create the periodic table?
A: No, he did not create the periodic table as we know it. He proposed the Law of Octaves, which was an important stepping stone. His work identified a key pattern—periodicity—but his specific model was flawed and incomplete. Dmitri Mendeleev is credited with developing the first widely accepted periodic table.
Q: What is the main difference between Newlands' octaves and the modern periodic table?
A: The main differences are the basis for ordering and the length of the periods. Newlands used atomic weight and had rigid periods of eight. The modern table is ordered by atomic number and has periods of varying lengths (2, 8, 8, 18, 18, 32), which accurately reflects the electron structure of the atoms. The modern table also has groups for transition metals and noble gases, which Newlands' table could not accommodate.
Q: Was Newlands ever recognized for his work?
A: Yes, but it took a long time. For years, his contribution was overlooked. However, in 1887, the Royal Society (the same organization that had once rejected his paper) awarded him the Davy Medal, their highest honor in chemistry, for his early work on element classification. This was a belated acknowledgment that he had been on the right track.
John Newlands' Law of Octaves was a brilliant, if imperfect, first attempt to bring order to the chemical universe. Though his musical analogy was mocked and his table was flawed, he was the first to clearly demonstrate a repeating pattern in the properties of the elements when arranged by atomic weight. His courage to propose a new idea paved the way for Mendeleev and others. In science, even "failed" theories are vital because they challenge old ways of thinking and point future scientists in the right direction. Newlands' story teaches us that perseverance in the face of criticism is often a key ingredient for scientific progress.
Footnote
1 Atomic Weight: The relative average mass of the atoms of an element, typically based on the mass of carbon-12. In Newlands' time, this was the best-known measurable property that increased with the mass of the atom.
2 Noble Gases: A group of chemical elements with similar properties; under standard conditions, they are all odorless, colorless, monatomic gases with very low chemical reactivity. This group includes helium (He), neon (Ne), argon (Ar), krypton (Kr), xenon (Xe), and radon (Rn).
3 Atomic Number (Z): The number of protons found in the nucleus of an atom. It is this number that uniquely defines a chemical element and determines its position in the modern periodic table. For a neutral atom, the atomic number also equals the number of electrons.