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430
Democritus and Leucippus
At about 430 BC The two came up with a theory that if you cut something in half enough times then you will eventually come up with something that you can't cut anymore. They named these particles "Atomos" meaning "uncuttable". They thought that Iron was made up of iron particles bound together with hooks, and clay particles were bound together with ball- and- socket joints. -
LaVoisier
LaVoisier developed the Theory of Law of Conversation of Mass. The theory states that i mass changes state it's mass stays the same, matter can't be created or destroyed it can only be rearranged. -
John Dalton
John Dalton discovered that matter was composed of atoms. -
Eugen Goldstein
He was one of the first to observe protons when he used a positive charge instead of a negative charge in a discharge tube. -
JJ Thompson
He approximated the mass of this ray that was creative and it was much lighter than a bit of hydrogen at that time. He predicted that the Cathode ray (produced from a discharge tube) was not a ray at all, but very small particles he called Corpuscles,or electrons. He knew that matter had neutral charge. So these electrons were dispersed throughout the atom. From that discovery he was able to make his famous Plumb Pudding model. -
Ernest Rutherford
He shot Alpha particles at a very thin sheet of gold foil, thinking that all of them would pass through, which most of them did. But some got reflected back at very large angles. The only explanation was that there was a positively charged mass in the middle, That was the first discovery of the nucleus. He also discovered that most of the atom is empty space. He also discovered protons after he shot alpha particles at nitrogen he would get a hydrogen ion. -
David Bohr
He took and analysed a lot of data from many experiments the rough position of electrons with this he made his famous Bohr diagram. His diagram showed electrons orbiting a nucleus. Different energy levels can hold different amounts of electrons. -
Werner Heisenberg
He discovered that you can't know the exact position of an electron it's momentum. the more you know about one the harder it gets to measure the other one. He also developed Quantum Theory. With this information he developed the idea that an electron's position was best described using probability. The areas much that have a higher probability than others he called these regions orbitals. -
Werner Heisenberg (continued )
Quantum Style diagrams are drawn as clouds with the intensity of color representing the probability of an electron being there. That is our modern understanding of atoms.