September 15, 2020
For educational institutions
⟶ Updated 26 Oct 2018 ⟶
List of edits
Democritus- A greek philosopher from around 400 B.C. came up with the idea of the atom. He said that if you cut something into smaller and smaller pieces then eventually there would be a piece which was so small it couldn't be cut anymore. He called them “atomos” and said that they were indestructible, have always and will always be in motion, there is empty space between atoms and everything is made of atoms.
Dalton 1803 - He proposed the law of multiple proportions which led directly to the atomic theory. He also created the mole system and a system of symbols to represent different elements. He determined that 5% of the male population and 10% of females were colorblind.
J.J Thomson 1897 - He identified the negatively charged electrons in the atoms m. He made the “plum pudding model” for the cell. He said that the electron was a component of all matter.
Rutherford 1911 - 1920 - He proposed the nuclear atom due to an experiment in 1911. He said that all of the positive charge and all of the mass of the atom occupied a small volume at the center of the atom and that most of the volume of the atom was empty space occupied by the electrons. In 1920 he said that the nucleus of hydrogen was a proton and said that the neutron was a thing.
Heisenberg 1925 - He came up with a more detailed version of an atom. He formulated quantum mechanics. He also contributed to theories of hydrodynamics.
De Broglie 1924- He developed a theory of electron waves. A wave confined within boundaries imposed by the nuclear charge would be restricted in shape. He predicted the wave nature of electrons. He was awarded the nobel prize for physics in 1929. Discovered all matter has wave properties
Chadwick 1932 - Discovered the neutron in 1932. Discovering the neutron led to discovering fission. Ultimately discovering the atomic bomb
Bohr 1913 - He said that electrons had a stable orbit around the nucleus. He came up with the bohr model. He also said the energy of the electron depends on the size of the orbit.
Sinking of the Titanic
World War 2
World War 1
My Mom's Birth
Millikan 1909 - He discovered the unit charge of electrons. That allowed people to calculate the mass of electrons.
About & Feedback