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Democritus and Atomos
In 400BC, a philosopher named Democritus, theorized about how all matter consisted of small particles that could not be broken. This thought was composed of logical reasoning and unfortunately had no proof to back it up. This is just the beginnig of what is now known as atoms. -
Lavoisier and the law of conservation of mass
Antoine Lavoisier, a French scientist, came up with the law of conservation of mass which says that mass can not be created or destroyed during a chemical reaction. Both Einstein and Dalton agreed with this idea later in history. Lavoisier died just five years after by guillotine, despite creating this building block for today's modern chemistry, -
Proust- Law of Definite Proportions
Proust was another French chemist that came up with the idea of the law of definite proportions. This law said that no matter the size, a chemical compound would have the same proportion of the element's mass. This was somewhat connected to Lavoisier's discovery and eventually they were both used in John Dalton's theories. -
John Dalton and the First Atomic Theory
John Dalton, put together the ideas of elements to atoms, the law of conservation of mass, and the law of definite proportions, to make up the first atomic theory. Dalton's atomic theory stated that elements were made up of atoms and they could not be divided. He also believed that atoms of an element were identical. These thoughts came up with the first official model of an atom now called the spherical model. Several of Dalton's claims were later proved incorrect with new discoveries. -
Thomson and the Plum Pudding Model
JJ Thomson disagreed with Dalton and questioned his theory. As a result of his doubts, Thomson performed his cathode ray experiment and came to the conclusion that there are subatomic particles specifically with charge, in an atom. He knew there must be a positive charge. The model he then created was called the plum pudding model, showing electrons which was different then Dalton's "chargeless" model. -
Einstein's math proves atom's existence
Einstein's work-In 1905, Albert Einstein used complicated phsyics to show the world that atoms really did exist. Einstein was the first one to back up the idea of atoms through math or experiments. Years later Ernest Rutherford performed an experiment to again display the atom's existence, but Einstein was first. -
Rutherford and the Nuclear Model
Rutherford conducted a Gold Foil Experiment, firing particles at gold foil, which led to the discovery of the nucleus and protons. Based on his results, Rutherford established that the nucleus is positively charged containing protons. In addition to that, he said that electrons roamed around the nucleus. Therefore, in his nuclear model, it showed electron surrounding the nucleus unlike Rutherford's that showed electrons inside one big atom. -
Niels Bohr and the Bohr Model
Bohr agreed with Rutherford's findings and expanded on his work. He found where exactly the electrons were located outsde of the nucleus. He said that these negatively charged electrons orbited around the nucleus on different levels. Bohr called this the electron cloud and electrons could jump from level to level using a certain amount of energy. -
Louis de Broglie and Wave theory
De Broglie had said that electrons had properties of those of a wave. This showed us about the physical nature of the atom. This also disproved Thomson's planetary model since electrons acted like waves not planets. -
Schrodinger and the quantum mechanical model
Edwin Shrodinger came up with an equation involving position and energy in atoms. In addition to that, he focused on his own new math called quantum mechanics, also knwon as the quantum theory, which showed that very small things behaved differently than larger things that are visible. Finally, he created the quantum mechanical model displaying what the electron cloud looks like. This model was a more specific display than Bohr's. -
Heisenberg and the Uncertainty Principle
Heisenberg's uncertainty principle spoke about the psoition and momentum of a particle. He said that the more you know about momentum the less you'll know about position and if you were to know about the position you wouldn't know much about the momentum. This displays a blurred line in nature and many people didn't accept it since it had no clear answer. -
Chadwick and the Modified Nuclear Model
Chadwick took Rutherford's experimental results and tried proving it another way. He confirmed the neutron's exsistence and displayed to the world the modified model. This model combined all of the past ideas to create the "modified" nuclear model.
