Benjamin Franklin's lightning Rod experiment promotes more experiments with electricity.
William Crookes discovers cathode rays and their properties.
Wilhelm Roentgen discovers X-rays
J.J. Thompson discovers that electrons are negatively charged,.
Antoine Becquerel proves radioactivity
Pierre/Marie Curie discover multiple radioactive elements and properties
1903 - 1911
Rutherford discovers the nucleus, and the protons contained within.
Millikan determine electrons charge and its constancy
Democritus proposes that everything is made of different, indivisible particles.
Anaxagoras Proposes there is no largest or smallest unit of mass, everything will grow and divide infinitely.
Dalton creates the first modern atomic model
Dalton proposed that all matter is made up of indivisible and indestructible atoms. He proposed that each element had unique atoms, with unique properties. This led him to conclude that chemical reactions were simply the rearrangement of atoms.
Niels Bohr proposes that electrons orbit the nucleus in quarantined levels
James Chadwick discovers the neutron within the nucleus.