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Democritus
Democritus was a famous personality in Greece because of his many philosophical ideologies. His theory revolves around the atoms that are in the atmosphere. It involbes atoms that are in all forms for example solids or liquids. His theory states that these atoms are all individually created and cannot be separated, no matter what scientific procedures are applied. Democritus also said that there is no specific size of an atom there are various sizes. -
John Dalton
In 1803 John Dalton came up with an atomic theory that consisted of five principles. 1 All matter is made of indivisble particles called atoms. 2 All atoms of the same elements are the same. 3 Atoms of different elements are different. 4 Elements combine together in small whole nimber ratios. 5 Atoms are small hard spheres like billiard balls. -
Ernest Rutherford
In 1871 Ernest Rutherford published his atomic therory which stated the atom had a central positive nucleus surrounded by negative orbiting electrons. This model suggested that most of the mass of a atom was contained in the nucleus and the rest of the atom was mostly emptey space. Rutherford came to this conclusion on account of his gold foil experiment. -
Henri Becquerel
While doing experiments with photography, Becquerel discovered that some chemicals decompose and give off destructive rays. -
J.J Thomson
In 1897 J.J Thomson through the plum pudding model/ choclate chip cookie model he discovered the electron. The Crooke's tube experiment showed J.J. Thomson that there were electrons in an atom.This experiment also showed that electrons are negativley charged. Which meant if an atoms were neautrally chareged as a whole there must be a positive charge. -
Marie and Pierre Curie.
Marie Curie studied the rays of Becquerel's experiments and discovered that they weren't rays at all, but tiny particles. Marie Curie won the nobel prize for her experiments. -
Robert Millikan
In 1909 Robert Millikan measured the charge of the electron with the oil drop experiment. In his experiment a spray bottle sprayed either oil or water droplets into a sample chamber. Then the droplets would pass through a number of other chambers. Particles that did capture one
or more electrons were attracted to the
positive upper plate and either floated upward
or fell more slowly. -
Niels Bohr
In the Bohr Model or planetary model the neutrons and protons (symbolized by red and blue balls in the adjacent image) occupy a dense central region called the nucleus, and the electrons orbit the nucleus much like planets orbiting the Sun (but the orbits are not confined to a plane as is approximately true in the Solar System). -
Quantum Model
The quantum model is a probability area an electron may be located in. In 1924, a French physicist named Louis de Broglie suggested that, like light, electrons could act as both particles and waves . His hypothesis was confirmed in experiments that showed electron beams could be diffracted or bent as they passed through a slit much like light could. -
James Chadwich
Chadwick discovered the neutron of the atom. He also confirmed that the atom contained a neutral particle. -
Aristotle
n 384 B.C the well respected philosopher Aristotle came up with a theory saying that all matter was made up of four element's water, fire , earth, and air. These four elements had four qualities dryness, hotness, coldness ,and moistness. Most people believed in this theory simply because he was one of the greatest philosophers of his time.
