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475 BCE
Leucippus
First greek to develop the atomic a theory. He stated that everything is composed by imperishable or indestructible and indivisible elements called atoms, later on his theory was complete by his aprentize Democritus -
442 BCE
Democritus
Democritu´s model stated that matter consisted of incisible particles called atoms and a void or empty space and said that atoms and indestructrible and unchageable and that all of them have diffeerent shape, size, color, etc.. -
John Dalton 1766-1844
He based his theory on fout parts. His first part of tthe theory stated the same as the one of Democritus and leucippus saying its indivisible and all that. The second stated that all atoms of a given element are identical in mass and properties. The third part stated that compounds are combnations of two or more different types of atoms, and the fourth part stated that a chemical reaction is a rearrangement of atoms. -
Eugen Goldstein 1850-1930
He discovered the cannal of rays or cathode rays and that this cathode rays travel from a positive charge one to a negative one and he discovered protons -
JJ Thomson 1856- 1940
He discovered elcetrons and that atoms can be divided. hee concluded that atoms are made of posittive cores and negatively charge particles within it. Hiss model consisted on a looking like pudding with cirles on top representing the electrons -
Ernest Rutherford 1871-1937
His model was called atomic atom or planetary model. His theory described the atom as a tiny, dense, with a positively charged core called nucleus in wich mass is concentrated around electrons revolving around the nucleus. -
Niels bohr 1885-1962
He said almost the same as rutherford saying that atoms are positively charged nucleus sorrunded by orbitng electrons. He was the one who discovered that electrons travel in separate arround the nucleus and that its orbiting determined its element. He contributed a lot to the understanding of nuclear fission and he made a theory named the liquid droplet theory that said that a liquid drop provides an accurate representation of an atom´s nucleus. -
James Chawick 1891-1974
He discovered the neutron wich contributed with the study of nuclear fission. He concluded that atoms are nucleus containig positively charged protons and neutral neutrons eith the rest of the space being empty space with negatively charge particles and that energy tell how many enegy elcetrons have
