September 30, 2021
For educational institutions
⟶ Updated 29 Oct 2018 ⟶
List of edits
Sinking of the Titanic 1911
Colmbus' First Voyage 1492
World War I 1914
My Birth 2003
Revolutionary War 1775
My Parents' Birth 1970 & 1976
World War II 1939
American Civil War 1861
~~~~~~~Democritus~~~~~~~ 400 BCE Theorized that all matter is composed of small, invisible particles.
~~~~~~~~~Aristotle~~~~~~~~~ 334 BCE Thought that all matter was made up of a combination of earth, air, water, and fire.
~~~~~Lavoisier~~~~~ 1774 Proposed the Law of Conservation of Mass
~~~~~~~~~~~~~John Dalton~~~~~~~~~~~~~ 1811 Proposed the Law of Multiple Porportions and the first Atomic Theory: All matter is made up of tiny indivisible atoms. Atoms of the same element are the same, of different elements are different, combine in whole number ratios to form compounds.
~~~~~~~~~~Berzelius~~~~~~~~~~ 1830 Simplified Dalton's symbols of elements Near-accurately calculated the atomic masses of 54 elements
~~~~~~~~~~Avogadro~~~~~~~~~~ 1811 Proposed Avogado's Hypothesis; equal volumes of gases, under the same conditions, will have the same amount of particles.
~~~~~~~~~J.J. Thompson~~~~~~~~~ 1897 Used cathode ray tubes to discover the mass-to-charge ratio of the electron and the proton. Creator of 'Plum Pudding Model'
~~~~~~~~~~Curie, M~~~~~~~~~~ 1898 Coined the term 'radioactivity' to describe some elements' rapid decay
~~~~~~~~~~Rutherford~~~~~~~~~~ 1911 Conducted a 'gold foil experiment' to discover that the nucleus is small & heavy, and that electrons orbit the nucleus in a mostly empty space.
~~~~~~~~Mosely~~~~~~~~ 1914 Determined the charge of the nuclei of most atoms
~~~~~~Chadwick~~~~~~ 1932 Discovered the neutron
~~~~~~Millikan~~~~~~ 1909 Determined the charge of an electron
~~~~~~~~~~Bohr~~~~~~~~~~ 1922 His model displayed electrons in a series of shells
~~~~~~~~~Planck~~~~~~~~~ 1900 Introduced the concept of quanta to explain glowing hot matter
~~~~~~~Schrodinger~~~~~~~ 1930 His model describes electrons as a cloud, because you can't determine the location of a specific electron easily
~~~~~~~~~~~~Heisenberg~~~~~~~~~~~~ 1927 Proposed the Principle of Indeterminacy; you can't know both the position and velocity of a particle
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