John Dalton

by Ryan from Fort Loramie

John Dalton
Charles Turner / Public domain via Wikimedia

John Dalton, the Father of Modern Atomic Theory, was born in the year of 1766. Growing up in Cumberland, England, John Dalton became a teacher (at the age of 12) along with being a lecturer to interest the public. He taught for ten years at the Quaker boarding school, but decided to bring his talents into the city of Manchester (Chemical Heritage Foundation, 2010, page 1). While in Manchester was when John Dalton, and his discoveries, really took leaps and bounds and began to take off. He was introduced to the Manchester Literary and Philosophical Society, and this organization allowed him with laboratories and other buildings where he could work with other very intelligent people. Early on, John Dalton took a serious interest in meteorology and would keep records of the weather almost daily all the way up until he died in 1844. For 57 years, he would go on to record over 200,000 records which were made possible by using weather instruments that were created by him. It has been said that John Dalton’s love for the weather put his attention high on the gas mixtures and atmospheric pressures. Both of these interests would go on to help him create Dalton's Law. At the age of 77, Dalton died on July 27, 1844 in the English city of Manchester.

Dalton’s Law, also known as Dalton’s Law of partial pressures, states that “the total pressure exerted by a gaseous mixture is equal to the sum of the partial pressures of each individual component in a gas mixture” (David Blauch, 2000-2001,2009 page 1). In my terms, this means that all of the mixtures within an object, equals the total sum of all of them combined. Common sense yes, but someone has to be the one to test what is believed to be obvious in the human mind and make it a proven fact. John Dalton did just that. This law is used to predict the concentration of the mixed gases to its pressure. In the real world, where people are much smarter than I, his law is expressed in mathematical terms as P(1) + P(2) + P(n) and P=pressure. The term (n) usually stands for oxygen or nitrogen, which are ideal gases that have minimal mistakes when testing them since they are so common in our atmosphere. Dalton’s Law also consisted of the Law of multiple proportions. It states that if two elements form multiple compounds, that the ratios of the masses of the second element combined with the first will be in ratios of small whole numbers (ISCID, Page 1). Though this all seems like a grand discovery of its time, it will compare to nothing of Dalton’s greatest discovery, Dalton’s Atomic Theory.

John Dalton greatest discovery, in my eyes and more than likely in many more on top of that, has to be his founding of the Atomic Theory. I have found that this theory has been developed almost by accident while toying and fiddling around with his preoccupation with gases during his meteorologist testing.

The Atomic Theory, proposed in 1803, has five parts:
1. All matter is made of atoms.
2. Atoms cannot be created, destroyed, or divided into smaller particles.
3. All atoms of a given element are identical in size, mass, and chemical properties. Atoms of one element are different from atoms of different elements.
4. Atoms combine in simple whole number ratios to form compounds.
5. In chemical reactions, atoms are separated, combined, or rearranged. (Mrs. Schmitmeyer’s notes, Unit two)

Dalton’s Atomic Theory was the base for every other scientist of that time as they tried to expand and broaden what he had started. For example, Niehls Bohr came up with the Bohr Atomic Theory that led for a more complete comprehension of quantum physics. John Dalton’s Atomic theory was not an idea not known to the scientists, as Democritus was actually the first one to propose the idea but did not have a complete comprehension to take his any further. Dalton’s Atomic Theory was the stepping block and the foundation for what today’s modern atomic theory has become.

Though this Atomic Theory was a huge breakthrough in the scientific world, it did possess a few flaws. First and foremost, it was discovered that there are particles that are smaller than atoms. JJ Thompson discovered negative charged particles called electrons by using a cathode ray tube to determine the ratio of charge to mass (Mrs. Schmitmeyer’s notes, Unit Two). Another flaw that scientists over the years have come to discover is that atoms can be destroyed by nuclear reactions. Dalton illustrated in his second point up above that atoms cannot be created, destroyed, or further divided into smaller parts, but we now know from nuclear reactions that these atoms are actually destroyed. Another flaw that I discovered was that his statement that atoms of a given element are similar is not necessarily true either, because isotopes have a different number of neutrons than the original atom.

Not only was he a prominent scientists and meteorologist, but he was also known for being the first person to explain colorblindness. John and his brother both suffered from red-green colorblindness. Interesting enough, Dalton believed that his colorblindness was due to a bluish aqueous humour (liquid) in his eye, and in his will he asked that when he died that someone perform an autopsy on his eyes. They did, and no bluish liquid was discovered in there. All of his work on the disease of colorblindness has now led to the term “Daltonism” being used as a synonym for colorblindness. John Dalton actually wrote and published a book on colorblindness in 1793, ten years before his atomic theory.

If I could ask John Dalton any question that my brain could muster, I think I would ask him why he never got married and began a family. John Dalton was as successful as any human being known today for what he accomplished, but would all of those accolades really make him truly happy if he had no family to share it with? My thinking is that an accomplished man like himself would have wanted to eventually settle down and raise a family, but I really have no valid explanation why he didn’t. I know this topic really wouldn’t bring much knowledge into my already crammed head, but I really would like to know the justification for why he chose not to marry or have kids.

All in all, John Dalton was the foundation pourer in the atomic theory world. He set the table for everybody else to keep broadening the subject to get a better understanding. Although his biggest accomplishment did possess some flaws, John Dalton will never be forgotten for his work in the creation of the first Atomic Model. John Dalton led the way for the rest of us to follow, and for this act he should continue to be studied and taught about for many years to come.

Page created on 12/13/2010 12:00:00 AM

Last edited 8/30/2021 11:28:19 PM

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Science History Institute - Learn more about Dalton