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Atomic discoveries through modern times
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Earliest Atomic Theory (Theories of the Atom emerging)
John Dalton (1766-1844), was an English Chemist. He came up with 4 VERY basic atomic theories while some were proven wrong this was the first atempt at actually coming up with atomic theories and the first attemt at understadning how it works. The laws are1) matter is composed of small particles called atoms 2)atoms of an element are all identical 3) Chemical reactions dont create or destroy aroms they rearrange them. 4) Atoms of each element combine in whole numbers of each other. 1&3 are righ -
First Periodic Table
Dimitri Mendeleev (1834-1907) Russian Chemistry Teacher (Like the person grading this hahaha) By his time there had been a lot of measurnment done to atomic weights and they were accurate and precise. Noticing a trend Dimitri used the data to organize the elemtns in the order of increasing atomic mass. This allowed him to predict the existence of other elements like germanuim for example. -
Radioactivity, Pre discovery and Ground Work
Henri Becquerel (1852-1908), He was accredited for discovering that a Uranium sample has the ability to expose a photographic plate while covered by black paper. Due to the fact that he experimented and found out hat the chemical state did not effect the results. He came to the conclusion that it was a property of the element Uranium. Therfore he abandoned his work. It would later be continured. -
Marie & Pierre Curie ( discovering Radioactivity and Properties)
Marie Curie (1867-1934), Pierre Curie (1859-1906), Picking up from where Becquerel left his work the curies discovered more radioactive materials such as Polonium, Radium, and Thorium. Pierre died so Marie continued the work on her own. She proposed the idea that the radioactive elements where emitting radiationand disentegrating over time. She described this praia "radioactivity" she is accredited for coining the term. She made it apparent that atoms can be slit up into subatomic particles. -
The Electron, Finally discovered.
J.J Thomson 1856-1940)Using Cathode Ray tubes which are evacuated tubes with tiny amounts of gas between two metallic plates one is negative (Cathode )and one is Positive (Anode). Whenever a test mass is places between the place (potential) a ray of electric current passes. He then proved that they were negative by placing two more plates on the sides, the ray bent towards the postive proving that its negatively charged, he concluded that all atoms have a (-) charge & a (+) charge grouped inside -
The Nucleus unlocked
Ernest Rutherford (1871-1937) Hans Gieger (1882-1945),
Ernest Rutherford using Thomsons "discovery" earlier that an atom was a solid mass, made up of positve & negative charges. Along side his student (Hans Geiger) Ernest devoloped an expirement, where the nuclei of helium atoms where fired at a thien peice of gold foil. The trajectory was monitored and recorded. Some particles recoiled, some were deflected minimaly, some were deflected greatly. They theorized that a nuclues & electrons orbit it
