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Developing the Idea of Atoms- Democritus
Greek philosopher, Democritus posed the question: "If you break a piece of matter in half, and then break it in half again, how many breaks will you have to make before you can break it no further?' Democritus believed that it had to end at some point. He called these basic matter particles 'atoms' -
Questioning the structure of atoms- John Dalton
It was not until the 1800s that scientists began to question the structure of atoms again. An english chemist, John Dalton performed experiments proving that various chemicles contained elementary particles named atoms. Although he had not yet discovered their structure he had proved something fundemental in their understanding -
The First Periodic Table- Dmitri Mendeleev
Dmitri Mendeleev attempted to classify each element by an exact principle. The only unchanging data that was available was the atomic weight of elements. He was able to create a table and therefore determine that several, unidentified elements should exist. This lead to the discovery of scandium, gallium and germanium. -
Radioactivity is discovered- Henri Becquerel
Henri Becquerel was using naturaly fluorescent minerals to study the properties of x-rays. He proved that uranium emitted radiation without an external source such as the sun and thus he had discovered radioactivity. -
Discovery of the Photon- Albert Einstein
A the time, physicists thought that light consisted of waves but it was Albert Einstein who discovered that the energy behaved like discrete particles. He called this 'Photons' -
Quantum theory- Niels Bohr
Niels Bohr developed the theory that certain properties only occur in discrete amounts (Quanta) -
The Discovery of Protons- Ernest Rutherford
In 1919, Ernest Rutherford finally identified the particles of the nucleus as positvely charged matter and discovered protons. -
Electron Discovered- J.J Thompson
J.J Thompson discovered the existence of electrons and introduced a model for the structure of the atom. He also found that electrons are negatively charged particles and therefore deduced that matter must have a positive charge. -
Discovery of the Neutrino- Clyde Cowan and Fred Reines
The discovery of a new elementary particle was made -
String Theory- Gabriele Venziano
String Theory was first formulated when Gabriele Veneziano described the strong interaction of particles.
