FC: Atomic Theory Time Line | Atomic Theory Timeline
1: Democritus came up with a theory stating that matter could not be divided into smaller pieces. He named the smallest piece possible "atomos." He also stated that atoms were solid, yet invisible, as well as indestructible. | Democritus 460BC-370BC | This theory was proposed in 400BC.
2: Aristotle 314BC- 322 BC | Aristotle proposed a fifth element that makes up space, called aether. He proposed this idea in 340 BC.
3: Antoine discovered the Law of Conservation of Mass. This states that mass can neither be created, nor destroyed. | Antoine Lavoisier Aug 26, 1743-May 8, 1794 | Lavoisier proposed this in 1798.
4: Dalton proposed an atomic theory stating four main points: 1) All matter is made up of atoms. 2) All atoms of an element are identical in mass and properties. 3) Compounds are formed from 2+ different elements. 4) Chemical Reactions are simply rearrangements of atoms. | John Dalton Sept. 6, 1766- July 27, 1844 | Dalton came up with this theory in 1803
5: Dimitri Mendeleev Feb. 8,1834- Feb. 2, 1907 | Dimitri created a periodic table of elements based upon their atomic mass, and grouped them through similar properties. | Dimitri published this table in 1869.
6: JJ Thomson Dec. 15, 1856-Aug. 30, 1940 | Thomson's model of the atom featured negatively charged electrons surrounded by (and thus balanced by) positively charged protons. | Thomson came up with this model in 1904
7: Ernest Rutherford Aug. 30, 1871- Oct. 19, 1937 | Rutherford created a model of an atom in which he proposed the idea of the nucleus. He proposed this model in 1911
8: Henry Moseley Nov. 23, 1887- Aug. 10, 1915 | Moseley created this table in 1914. | Henry Moseley created the modern periodic table, arranged by increasing atomic number.
9: Niels Bohr Oct. 7, 1885-Nov. 18, 1962 | He created this model in 1922 | Bohr made the first model of the hydrogen atom.
10: Shrodinger presented these findings in 1930 | Erwin Shrodinger Aug. 12, 1887-Jan. 4, 1961 | Shrodinger created the Quantum Mechanical Model of the Atom. This stated that electrons do not orbit, but rather move in orbitals.
11: James Chadwick Oct. 20, 1891-July 24, 1974 | James Chadwick discovered the neutron. He made this discovery in 1932