Theorized that matter is homogeneous, consisting of small indivisible particles, called atoms which are constantly in motion, and form compounds via collisions. This could be considered the first atomic theory.
460 BC - 370 BC
Democritus developed Leucippus's atomic theory. He theorized that atoms had space in between each other, were indivisible, and could not be destroyed.
First Atomic Theory
Approx. 400 BC
384 BC - 322 BC
Disagreeing with Democritus, Aristotle believed that the world was made of 4 elements: air, water, fire, and earth. This was perhaps the first theory that elements existed.
January 4, 1643 - March 31, 1727
Proposed a mechanical universe where small solid masses were in motion.
1706 - 1790
Proposed matter had positive and negative charges after his famous kite flight is 1752
1743 - 1794
Stated the first law of conservation of mass in 1789.
September 6, 1766 - July 27, 1844
Discovered the atom in 1803
September 22, 1791 - August 25, 1867
Discovered method of splitting molecules using electricity in 1832, later making laws of electrolysis
June 16, 1801 - May 22, 1868
In 1859, built first functioning cathode ray, which was later used to theorize that atomic particles each contained certain charges.
William C. Roentgen
March 27, 1845 - February 10, 1923
Discovered that x-rays could pass through solid objects in 1895.
December 15, 1852 - August 25, 1908
Discovered some chemicals spontaneously decompose and give off penetrating waves.
December 18, 1856 - August 30, 1940
Found electrons and isotopes, in 1906 was awarded nobel peace prize for discovery of the atom.
November 7, 1867 - July 4, 1934
Discovered radioactivity in 1898
March 22, 1868 - December 19, 1953
Discovered the charge and mass of an electron in 1909
August 30, 1871 - October 19, 1937
His Rutherford model in 1911 theorized that atoms were mostly empty, known as "the father of nuclear physics".
March 14, 1879 - April 18, 1955
First to show a way to prove the existence of atoms.
October 7, 1885 - November 18, 1962
Created the Bohr model in 1913, with electrons orbiting around a central nucleus.
August 12, 1887 - January 4, 1961
Proposed electrons behaved in the matter of an electron cloud.
October 20, 1891 - July 24, 1974
Discovered neutron in 1932, and theorized the neutron exists to stabilize the atom.
Louis de Broglie
August 15, 1892 - March 19, 1987
Dicovered that electrons behaved like waves under certain conditions.
December 5, 1901 - February 1, 1976
Created the Uncertainty Principle, stating that the exact location and energy of an electron cannot be determined simultaneously.
May 29, 1929 - September 24, 2017
Theorized the Higgs Boson Particle A.K.A. the god particle, in 1964.