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400
Democritus. Indivisible Sphere Theory
(Note: The year is 400 BC) Democritus stated that atoms are not all the same, thay are indivisible physically, they are eternal, and always moving. He made a theory on this to explain why and how atoms were so small, and what they were about. He proposed the most advance atomic theory of his time. -
Oct 13, 600
Aristotle. 4 Elements Theory.
(The year is 384-322 BC) He found that matter is made of 4 elements, fire, water, earth, and air. With all this, he came up with the theory of motion. His theory pushed Democritus' aside. giving the world a wrong understanding of atoms. -
Antoine Lavoisier. Law of Conservation of Matter
He had the first version of the Law of Conservation of Matter. He also named oxygen and hydrogen. He invented the first periodic table, which had 33 elements. -
Charles Augustin de Coulomb. Coulomb's Law.
He had Coulomb’s law which stated the interaction between electric charges. He also published the laws of friction. He used windmills and the elasticity of fibers and metals to come up with this law. -
John Dalton. Father of Atomic Theory.
Father of modern atomic theory.He proposed the atomic theory. He inferred proportions of elements in compounds. He found the atomic weight, and chemical symbols. He also had the most useful atomic theory of matter. He rediscovered Democritus' theory. -
Sir William Crookes. Canal Rays, Cathode Rays, Plasmas.
He came up with thallium and helium. He investigated canal rays, cathode rays, and plasmas. He used electricity in gases, and found as the pressure went down, the electrodes began to emit rays. -
W.K. Roentgen. X-Rays.
He discovered x-rays when he was working with Sir William Crooke’s tube. He also found that x-rays pass through different materials at different temperatures. He was doing an experiment on cathode rays when he discovered x-rays. -
Becquerel. Radioactivity.
He came up with radioactivity. He found this out from unknown x-rays waves, which were produced by uranium. Penetrating radiation was also discovered by Becquerel. He also discovered that uranium was able to expose a photographic plate on black paper, and didn’t depend on the chemical state. -
J.J. Thomson. Plum Pudding Model
He found electrons and subatomic particles when he was working with cathode ray tubes. He was working with glass tubes and electricity when he discovered electrons. His discoveries helped our ability to understand about science to progress. -
Marie & Pierre Curie.
They both picked up on Becquerel’s work on uranium, which lead them to find the elements radium and polonium. Though Marie went further with the radioactivity of elements, she didn’t get very far. All she said was, “they were somehow disintegrating over time and emitting radiation that exposed the plate.” ~ Marie Curie. Pierre went on to say that atoms might be composed of even smaller things. -
Max Planck. Quantum Theory.
He was the person who came up with the original quantum theory. To come up with this, all he did was research from pervious scientists and a little bit on his own, and then wrote a book on the quantum theory (the theory: the behavior or matter and energy in an atom). He also was looking at color changes from energy. He also made a math equation to help with this theory. -
Albert Einstein.
First, he found that nature and matter intertwine somehow, the theory of measurement came about from this. Second, he publish 5 papers on electrons. These contributed to the quantum mechanics. He said, “light consists of quanta, bundles of energy which behave somewhat like particles.” ~Albert Einstein -
Ernest Rutherford. Rutherford Experiment.
He ionized gas using radiation, and found alpha and beta waves. He used his research and the magnetic properties of iron to find radio waves. He also discovered the atomic nucleus using others research and findings. To find this he did the Rutherford experiment. Briefly, he used a thin foil made of gold metal to find positive and negative charges in an atom. -
Niels Bohr. The Bohr Model.
Niels figured out the structure of the atom, and their radiations. He also discovered the principle of complementary. He introduced electrons from the book he wrote on the structure of the atom. He also started the basis of the quantum theory. He gave the most advance atomic model yet. -
Electron Cloud Model.
Discovered by Erwin Schrödinger and Werner Heisenberg. They said an atom consists of a dense nucleus and many proton and neutrons and is surrounded by electrons, but they all have different energy levels, and different charges. -
Planetary or Solar System Model.
Both Rutherford and Bohr contributed into this model. Rutherford said the atom is mostly empty space with a nucleus that has a positive charge surrounded by negative electrons. Then Bohr said they circulate the atom. -
Erwin Schrödinger.
Erwin’s contributions were the wave mechanics and quantum mechanics. He wrote papers on wave mechanics, which lead him to the quantum mechanics. To find these theories out, he worked out math equations and used statistics.
