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John Dalton
John Dalton was one of the pioneer's of atomic theory. He came up with the idea that different elements could be told apart based on their weight (eg.Oxygen's atomic weight is 15.99 and Nitrogen is 14.01). At the time this was a massive discovery, it allowed scientists to begin to seperate elements they had at one point considered to be the same due to no noticeable differences. He also identified many basic properties of atoms, including facts like all matter is composed of atoms, atoms cannot -
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Atomic Structure Timeline
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John Dalton - Continued
be made or destroyed, all atoms of the same element are identical, etc. His fascination with atoms led him to create atomic theory. This interest in atoms stemmed from his fascination with weather. This fascinationmade him want to understand gases and air and in general atoms as a whole.John Dalton Biography -
Dimitri Mendeleev
Widely known as the father of the periodic table, Dimitri Mendeleev contributed much to the progression of atomic theory. His influence stemmed from his making of the periodic table. Dimitri was the first chemist to group elements by name, atomic mass and physical and chemical properties. He realized that when elements were arranged in increasing atomic mass, their were similarities in chemical properties between elements at regular intervals ( hence the name Periodic Table). Dimitri and other -
Dimitri Mendeleev - Continued
chemists at the time used the periodic table to predict the atomic weight and chemical properties of elements not yet isolated. Therefore the periodic table allowed scientists to understand elements that would not be discovered for many years.
Dmitri Mendeleev: Great Minds -
J.J. Thompson
J.J. Thompson was the first scientist to "understand" the atom. Scientists before him had identified the atom and knew it was extremely small, but none knew what the atom was made of. He discovered the atom contained negative and positive charges. Today they are known as electrons (-) and protons (+). He also discovered that atoms were spherical and had a positive charge. His theory about the atom was known as the "plum pudding" model. This was because he thought the atom simply had protons and -
J.J. Thompson
electrons floating around inside a spherical shape, somewhat like plum pudding with the plum distributed throughout the pudding. This all started from his discovery of something called a corpuscle which he discovered using a cathode ray (a stream of electrons emiited by electrical tubes) the corpuscle is now now known as the electron. J.J. Thompson -
Ernest Rutherford
Enernest Rutherford continued to develop what J.J. Thompson had started. He continued to research what the atom was made of, he came to the conclusion that the "plum pudding" model was incorrect but Thompson had still discovered valuable information. Ernest conducted experiments and realized that at the center of an atom was a positive nucleus surrounded by orbiting electrons. His famous gold foil experiment also led him to discover that most of the atom was made of empty space. His gold foil -
Ernest Rutherford
experiment consisted of him firing readioactive particals thorugh minute metal foils, and then detecting them with screens coated with zinc sulfide. Essentially this allowed Ernest to realize there was a large amount of empty space, and the atom contained a nucleus. Ernest Rutherford Biography -
H.G.J. Moseley
H.G.J. Moseley was another extremely important chemist who contributed to a deeper understanding of the atom, and the refurbishing of the past periodic table into the one we know today. H.G.J. Moseley used x-ray to deeply study the atom, the result of his research was the understanding that the number of protons in the nucleus was equal to the atomic number. This shook the very foundations of the periodic table as it caused the elements to be ordered by atomic number rather than atomic weight. -
H.G.J. Moseley
This new periodic table eradicated the problems that were previously present in Mendeleev's periodic table. Due to H.G.J Moseley's work the periodic table is now a flawless piece of scientific ingenuity. An Ode To H.G.J. Moseley -
Niels Bohr
Niels Bohr was an extremely important contributor to atomic theory. He created a diagram that would allow scientists to display distinct atoms of specific elements using a set out template. This was important for labs and experiments, because now other scientists would understand the universal diagram for a specific element. Along with his creation of the diagram, Niels Bohr discovered that electrons separately orbited around the nucleus, therefore progressing the -
Niels Bohr
understanding of the atom further. Niels was an important part of atomic theory, and is the reason we can now tell atoms apart with basic diagrams. Niels Bohr Diagram
