Work on Meteorology, Work on Color Blindness, Work on Gases, Work on the Atomic Theory
Dalton published the atomic theory in 1808 in a book called A New System of ChemicalPhilosophy. His theory was based on three important propositions. The first was that all matter is composed of extremely small, indivisible, and indestructible particles called atoms. The second was that the atoms of one element are all exactly alike in every respect including weight but are different from the atoms of every other element. The last was that when elements combine to form compounds theiratoms combine in simple numerical proportions such as one to one, two to one, and four to three.
The ideas of atoms had been suggested centuries earlier by the Greek philosopher Democritus, so the concept was not entirely unfamiliar to Dalton's contemporaries. But Dalton's complete formulation of a consistent theory was a breakthrough. One of the most important features of the theory was itsproposal that atoms differed from each other by weight. This was something measurable, making Dalton's the first quantitative atomic theory ever advanced.
Chemists had long puzzled over why a substance such as copper carbonate, however prepared, always contained the same proportions by weight of copper (five parts), oxygen (four parts), and carbon (one part). Dalton's theory that elements combine atomby atom in simple numerical proportions explained it, because if all atoms of a particular element have the same weight, they must have definite combining weights.
Dalton tried to work out the relative weights of different atoms from the proportions by weight of the elements in certain compounds, so becoming the first to prepare a table of atomic weights. He also drew up a system of notations torepresent elements, discarding the obscure drawings that had been handed down from the alchemists of ancient times. He created clear sysmbols to stand for the atoms of different elements, and used them in drawings that showed what took place during chemical reactions. For example, molecules were shown as groups of atom symbols linked together.
Analyzing Sugar -- contain his discovery that certainanhydrates, when dissolved in water, cause no increase in its volume.
John Dalton died on July 27, 1844.
Awards and Honors
As a devout Quaker, Dalton shunned public acclaim, even refusing to be nominated for membership of the Royal Society. In 1822 his determined admirers elected him to the society without his knowledge, and in 1832 he was persuaded to accept a Doctorate of Science from theUniversity of Oxford. Dalton had a problem in wearing his Oxford gown, however, because it was scarlet and Quakers wore no red. Because he could not bring himself to disappoint his friends, Dalton fell back on his color blindness and remarked that the University gown appeared gray to him.
In 1833 the British government conferred on him a pension of £150, which was raised to £300 in 1836.
All buttwo of the statements in Dalton's Atomic Theory are still considered valid today. The statement "Atoms cannot be subdivided, created, or destroyed into smaller particles when they are combined, separated, or rearranged in chemical reactions" is inconsistent with the existence of nuclear fusion and fission. The statement "All atoms of a given element are identical in their physical and chemicalproperties" is also not precisely true, as the different isotopes of an element have varying numbers of neutrons in their nuclei, though the number of protons remains consistent.
His background is rather unique, having been born in New Zealand, a country which, within a mere 50 years of formal European settlement of that remote British Colony, could admit him to its, already 20-year-old, university....