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460
460 B.C (Democritus)
A Greek philosopher named Democritus thought if you broke a piece of matter in half, and keep on breaking it in half, it would eventually be the smallest bit of matter. He called this an atom. Rough depiction of how Democitus thought an atom would look like. -
1704 (Isaac Newton)
Isaac Newton proposed that the universe was mechanical made with solid masses in motion. He was the one to believe that atoms were not stationary, but were always in motion. Isaac's image of atoms in motion. -
1803 (John Dalton)
John Dalton was a scientist that proposed an atomic theory with spherical solid atoms based on measurable mass. Dalton's theory of atomic mass. -
1869 (Dmitri Mendeleev)
Dmitri Mendeleev arranged elements into groups by their atomic weight. There were 8 groups in which he grouped them, he discovered that the properties of elements "were periodic functions of the their atomic weights" this is known as the Periodic Law. An early look of the period table according to Mendeleev. -
1884 (George Johnstone Stoney)
George Johnstone Stoney introduced the electron. Says it is a fundamantal unit of electricity. Through his work of the kinectic theory of gas, Stoney introduced the term Electron. -
1897 (Sir Joseph John Thompson)
Sir Joseph John Thompson discovered electrons, proposed that electicity was made of discrete negative particles. Atoms had electrons and protons swimming inside. How Thompson thought an atom should look like. -
1905 (Albert Einstein)
Albert Einstein published the equation E=mc2. Engergy=mass x speed of light squared. Equation helped understand energy. -
1911 (Ernest Rutherford)
Ernest Rutherford discovered that atoms have their positive charge from their nucleus. His interpretation of the atom is the model that is used today. Through his gold foil experiment, Rutherford was able to conclude that an atom has a central charge, that had electrons surrounding it. -
1914 (Henry Mosely)
Henry Mosely created laws for the elements to be grouped by the atomic number, or amount of protons in the nucleus. Image of how Mosely grouped the elements. -
1922 (Niels Bohr)
Niels Bohr explained atomic structures so the elements were sorted by successive order by the number of shells in their atomic structure. Niels Bohr ordered elements depending on the number of shells they had on their atomic structure. (H=1) Niel Bohr also made the current model for the atomic structure by using orbits. -
1932 (Sir John Chadwick)
Sir John Chadwick discovered of the neutral atomic particle in a nucleus-had a similar mass to a proton. This discovery made it possible to make elements heavier. Discovered that the nucleus was similar to the number of protons.
