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Newton hypothesised that there were small particles that constantly move.
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Dalton proposed the first atomic theory
He beleived that spherical solid atoms were based upon measurable properties of mass.
He used the Billard Ball Model -
He studied the effect of electricity on solutions, coined term "electrolysis" as a splitting of molecules with electricity, developed laws of electrolysis
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He created one of the first discharge tubes A.K.A. a cathode ray tube and created a glow on the walls of the tube
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Mendeleev creted the first version of the Periodic Table and used it to understand that elemens were periodic functions of their atomic weight(Periodic Law)
He also helped the scientific world predict the mass and atomic number of unknown elements. -
Proposed the electromagnetic theory
He beleived that electric and magnetic feilds filled the void. -
Stoney beleived that electricity was made of discrete negative particles later known as electrons
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Used a CRT to study "canal rays" which had electrical and magnetic properties opposite of an electron.
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Using a CRT he observed that nearby chemicals glowed. Further experiments found very penetrating rays coming from the CRT that were not deflected by a magnetic field. He named them "X-rays".
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While studying the effect of x-rays on photographic film, he discovered some chemicals spontaneously decompose and give off very pentrating rays.
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Thomson discovered the electron.
He also created the plum pudding model -
She studied uranium and thorium and called their spontaneous decay process "radioactivity". She and her husband Pierre also discovered the radioactive elements polonium and radium.
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Soddy observed spontaneous disintegration of radioactive elements into variants he called "isotopes" or totally new elements, discovered "half-life", made initial calculations on energy released during decay.
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He discovered that energy didn't move at a steady rate, but instead as discrete units of energy known as quanta.
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He disagreed with Thomson plum pudding model and postulated a "Saturnian" model of the atom with flat rings of electrons revolving around a positively charged particle.
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Proposed the famous theory of relativity or as an equation E=mc^2
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He creted the Geiger vounter which measures radioactivity
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He propesed used his oil drop experiment to determined the charge and the mass of an electron
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Using alpha particles as atomic bullets, he probed the atoms in a piece of thin gold foil (Gold Foil Model). He established that the nucleus was: very dense,very small and positively charged. He also assumed that the electrons were located outside the nucleus.
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Bohr discovered that electrons orbit around the nucleus and it is shown in his model
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Using x-ray tubes, he determined the charges on the nuclei of most atoms. He wrote"The atomic number of an element is equal to the number of protons in the nucleus". This work was used to reorganize the periodic table based upon atomic number instead of atomic mass.
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Discovered the existence of isotopes through the use of a mass spectrograph.
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He discovered that electrons had a dual nature similar to both particles and waves.
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Viewed electrons as continuous clouds and introduced "wave mechanics" as a mathematical model of the atom. He also defined an orbital as the area in which electrons can be found
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He described atoms by means of formula connected to the frequencies of spectral lines. Proposed the Uncertainty Principle of Indeterminancy - you can not know both the position and velocity of a particle.
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Proposed the existence of anit-particles.
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Using alpha particles discovered a neutral atomic particle with a mass close to a proton. Thus was discovered the neutron, and his model of said neutrons
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He invented the particle accelerator to acheive high energy levels
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She conducted experiments verifying that heavy elements capture neutrons and form unstable products which undergo fission. This process ejects more neutrons continuing the fission chain reaction. she also discovered Barium from bombarding neutrons
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Synthesized 6 transuranium elements and suggested a change in the layout of the periodic table.
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Conducted the first controlled chain reaction releasing energy from the atoms nucleus.
He also helped create the first nuclear reactor.
