09-06 – John Dalton's Chemical Symbols

Two hundred and fifty years ago today, John Dalton was born in the small town of Eaglesfield, Cumbria, in England. Though his background was entirely unassuming, he would go on to take pioneering steps in developing our ideas about elements and atoms, as well as making the first attempt at devising a symbol-based nomenclature for the elements. Here we take a brief look at his life and achievements.

Dalton’s background wasn’t exactly what you’d expect for someone who’d go on to revolutionise our understanding of atoms. He was born to a Quaker family, and lived in poverty as a child – so much so that he had supposedly starting working teaching at a local school by the age of twelve. As Quakers were seen as dissenters by the Church of England, Dalton was barred from attending English universities, and as such received no formal education in chemistry. Instead, all he knew about science was gleaned from friends and acquaintances.

By the time Dalton reached his late twenties and early thirties, he was starting to put out publications. These weren’t yet chemistry-based though – in fact, amongst his first publications were books on the subjects of meteorology and (bizarrely) English grammar. He did, however, dabble in some science at this point; Dalton himself and his brother both suffered from colour-blindness, and he carried out research on it, recognising that it was likely a hereditary condition. Though it’s a not so commonly used name these days, colour blindness was also known as Daltonism as a result of his research.

On a slightly weird related note, Dalton asked for his eyeballs to be preserved after his death to try and confirm some of his theories regarding colour blindness, and they are; if you fancy a bit of chemist eyeball tourism, you can pop along to The Manchester Literary and Philosophical Society, though I’ll confess I have no idea if they actually have them on display.

Getting back to chemistry, and Dalton finally got around to pondering some chemical problems at the beginning of the nineteenth century. First, he carried out a series of experiments on gases, which lead to a number of published essays and birthed Dalton’s Law of Partial Pressures. More famously, though, he’s remembered for his work on developing the beginnings of modern atomic theory.

So what did he actually do? Well, Dalton was the first scientist to properly ponder the nature of atoms, and to suggest that elements are made of these extremely small particles. Technically, the idea of atoms had been around since the Ancient Greeks, and other chemists had certainly suggested that at some point, matter must become indivisible. Dalton, however, was first to suggest that atoms of different elements would have different masses, and therefore different sizes. He also stated that when elements combine to form chemical compounds, they do so in whole number ratios.

Further to this, Dalton developed what we consider to be the first attempt at devising symbols for atoms and molecules. In 1803, he produced a number of chemical symbols for the known elements of the time, and also created some diagrams using these symbols to illustrate a range of common molecules. He didn’t get it all right: one of his suggestions was that elements mainly combine in binary combinations – in other words, the compound form would only have one atom of each element. This led him to believe the formula for water was OH, whereas we now know that it’s H2O.

Dalton went on to carry out work on trying to determine the atomic weights of elements, as well as continuing his more eclectic publications. Other scientific areas in which he dabbled included musings on the origins of dew, and the colour of the sky. His atomic symbols were succeeded by those of Jöns Jacob Berzelius, a distinguished Swedish chemist, and it is derivatives of these symbols that we use today. Dalton was by all accounts unimpressed by Berzelius’s notation, but he remains renowned for his contributions to our understanding of atoms, even if some portions of his theory have been proven to be incorrect.

Dalton never married, and died in Manchester in 1844. His original scientific papers were stored at the Manchester Literary and Philosophical Society, but were sadly damaged by bombing during World War II; though not the collection was not completely destroyed, a large portion of it was lost.

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References & Further Reading