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300
Democritus
First person to propose the idea that matter was not infinitely divised. He believed matter was made up of tiny individual particles called atoms. He believed that atoms can not be created, destroyed, or further divided. -
Period: 300 to
Atomic Theory Time
Here is the timeline in which the Atomic Theory was developed. -
Antoine Lavosier
French chemist whose persistance in percise experiments led to the law of conservation of mass. He was the first to announce that air was made up of two gases- oxygen an nitrogen. -
Law of conservation of mass
States that mass is neither created nor destroyed during a chemical reaction but is conserved. -
John Dalton
Discovered Atomic Theory. -
Dalon's Atomic Theory
Was based on the premise that the atoms of different elements could be distinguished by differences in their weights. -
Dimitri Mendeleer
Russian chemist who divised the original periodic table of the elements. -
Cathode Ray Tube
an electric current passed through a gas inside a sealed tube. The ray would bend away from a negative field. -
J.J Thomson
discovered the electron, a negatively charged particle more than two thousand times lighter than a hydrogen atom. -
Plum Pudding Atomic Model
an atom made of thousands of electrons would have a very high, negatively electric charge. This was not observed, as atoms are usually uncharged.