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350
Aristotle
Aristotle (350 B.C.) disagreed with Democritus's model of the atom. because many of Democritus's ideas were more thought based than scientifcially based. For this reason, Aristotle strongly disagreed with Democritus. he belived all substances were made of earth, fire, air, and water. Aristotle did not have an atomic model due to the fact that he thought atoms did not exist. -
400
Democritus
Democritus was the first scientist to create a model of the atom. He was the first one to discover that all matter is made up of invisible particles called atoms. He also discovered that atoms are solid, indestructible, and unique. His model was just a round solid ball. -
440
Empodicles
Suggested there were 4 elements Water, Fire, Earth and air. It seemed logical because when things caught on fire it leased moisture and air can befelt and ashes show the earth contained -
Antoine Lavoiser
Lavoisier was a French nobleman that founded several elements and put the first table of elements together. He used the ideas of fire, earth, air, and water to create experiments invesigating combustion and also oxidation. By knowledge of atomic bonding, he discovere elements like oxygen, hydrogen, and sulfur. He also found out that water was made of oxygen and hydrogen, and air included nitrogen. Lavoisier also created the first chemistry textbooks and tables. -
John Dalton
John Dalton was an English chemist that created the Atomic Theory of Matter,in this theory he showed that all matter is made of atoms and that atoms cannot be created or destroyed and also atoms of different elements combine in whole ratios to make chemical compunds. His theory would later contribute to the advancement in the atomic model. -
Henri Becquerel
Henri Becquerel was born into a family of scientists. With influences from his father and grandfather, Bequerel worked with properties of the atom, such as magnetism and radioactivity. His discovery of radioactivity allowed later scientists to perfect the atomic model. -
J.J Thompson
J.J. Thomson was a very important scientist when it came to the atomic model. Up until his time, all models of the atom looked like a large solid ball. but J.J. Thomson discovered the electron, which led him to create the "plum pudding" atomic model. In this model, he thought that the atom was mostly positive, and negative electrons wandered around the atom. -
Marie And Pierre Curie
Marie and Pierre Curie were a European couple that contributed to atomic chemistry by exploring the mysteries of radioactivity. After radiation was discovered by Henri Baquerel, Marie decided to look further into this discovery. Through this she and her husband discovered the elements radium and polonium Her discovery later added to the atomic model. -
Max Planck
Max Planck was a German scientist that created the Quantum Theory. In this theory, Planck stated that energy was given off in little packets of energy. He discovered that the energy in wave form is restricted to specific ammounts. This discovery led to the understanding of energy levels in atoms, this discovery later added to the advance in the atomic model. -
Robert Milikan
Robert Millikan was an American scientist that was very interested in J.J. Thomson's finding of the electron. Millikan wanted to prove J.J thompsons hypothesis on electrons are 1000 times smaller than the whole atom. He preformed an "oil-drop experiment" in which he found that J.J. Thomson hypothsis was correct. Robert Millikan was also involved in the Quantum Theory -
Ernest Rutherford
Ernest Rutherford was another scientist that changed the atomic model. He felt that J.J. Thomson's model was wrong so he decided to created a new one. He created the nucleus, and said that instead of the positive matter being the whole atom, it was just in the middle. He also said the atom was mostly empty space and that the electrons surrounded the positive nucleus. This model influenced one of his own students to perfect the atomic model later on. -
James Chadwick
Jame Chadwick was an English scientist that discovered the neutron. Before this discovery, Rutherford had concluded that the nucleus was made of positive matter. but Chadwick found that the neutron.
