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100
Aristotle
Ranging within the time period of 384-322 BC, Aristotle believed essentially in four elements: earth, air, fire, and water. Aristotle believed one could infinitely split matter in half, and it would just produce smaller matter. This view was held popular for approximately 2000 years. -
100
Democritus
In the years of 460 to 370 BC, Democritus was very integral in the advancement in the understading of the atom. He prooposed the existence of an "ultimate particle", this he called "atomos". He didn't believe this particle could be divided. He thought all things were made of this same material, but varied in shape and size. However, this was simply philosophical at the time, as he couldn't prove it, and the popular belief lied more towards Aristotle's theory. -
Antoine Lavoisier
Lavoisier was the first to make an extensive list of the elements, elements being what he primarily dealt with. He developed the Law of Conservation of Mass. -
John Dalton
John Dalton made massive steps towards the understanding of atoms. He began to explain how chemicals behaved, opening up bounds of room for experimentation. Dalton believed that everything was made up of atom, and that atoms couldn't be divided any smaller than they were. He explained chemical reactions as the rearragnement of atoms. He also described atoms as circular with a solid mass, he made huge steps toward understanding atoms and their structure, and the way of interaction. -
Henri Becquerel
Henri Becquerel came from a family of scientists, and had his greatest contributions centered around the discovery of radioactivity. It was essentially the recognition that chemicals could spontaniously decompose, giving off a very penetrating beam. -
Marie and Pierre Curie
Pierre and a student are responsible for the dscovery of nuclear energy. They discovered new elements, and had large influence on the creation of a unit for radioactviy -
Max Planck
Planck developed "Planck's Curve" which incorporates both the "Stefan-Baltzmann Law" and "Wien's law". He also disagreed wtih the model suggested for the atom by Rutherford. -
J.J. Thomson
Thomson sought to update the atomic model from Dalton's model, from this came the plum pudding model. He suggested the mass of the atom coming from positive and negative particles. He suggested the particles were mostly positive, with some negative, he had discovered the electron. -
Robert Millikan
Millikan made his greatest contribution through performing an oil drop experiment. He worked on this with Harvey Fletcher, however, he took sole credit. This experiment helped to determine the charge of an electron. -
Ernest Rutherford
Ernest Rutherford advanced the atomic model to recognize the central positively charged nucleus to be surrounded by negatively charged orbiting electrons. He determined that the most mass of the atom lied in the nucleus. This was determined through performing an experiment revolving around firing radioactive particles and detecting them using a zinc coated screen. 1 in 800 of them were deflected from the screen, the atom was mostly empty space. Rutherford was the student of J.J. Thomson, -
Niels Bohr
He developed the idea of a small positively nucleus surrounded by electrons in an almost leveled arrangement to fit the number present with a certain number of electrons residing in each level. -
Henry Mosely
Henry Mosely essentially rearranged the periodic table, he changed it from progressing by atomic mass to progressing by positive charge (number of protons). He made occur in relation to his proclomation that the energy of x-rays permitted increases linearly as the periodic table does. -
Werner Heisenberg
Werner Heisenberg developed the uncertainty principle. He established that electrons do not travel in near orbits. He then moved to say that all electrons photoms. He calculated the behavior of electrons. He also made contributions to atomic-theory- quantom mechanics. -
Erwin Schrodinger
Schrodinger made his contributions greatly in that he developed a set of equations of wave functions for electrons. He helped to establish that one could describe (only) the probability of where an electron could be. He helped determine that the areas of the greatest density had the largest probability of having electrons lie there. He also helped to establish the concept of orbitals, as electron dense clouds. -
James Chadwick
James Chadwick made one of the largest advancements in the understadning of the atom, he discovered the neutron. IIn addition to this, he also collaborated with Ernest Rutherford.