DemocritusHe stated all matter is composed of eternal,
indivisible, indestructable and indefinately small
substances that cling together.
Dalton-originated the modern atomic theory in the early 19th century. The atomic theory was that all atoms were indestructible particles and have the same atomic weight.
-He said atoms were spheres beacuse spheres were the "divine shape"
Thompson-Discovered the electron
-Proposed a new model of the atom
-Said the tiny negative charge electrons must be
embedded in a cloud of posative charge since atoms
have no charge.
-Plum-pudding model, 1904, the atom is composed of electrons
Rutherford-His theory tells us an atom consists of a small,
dese, positively charged nucleous with electrons
-Gold foil experiement: It measured the deflection
of alpha particles that were directed onto a sheet of gold foil
GoldsteinEugen Goldstein is best known for his studies of electric discharges in gases at low pressures in 1886. Cathode rays were invisible emanation coming from the discharge tube. It showed that rays could give off a sharp shadow and that they emitted perpendicular to the cathodes surface. He also realized that they can be deflected by a magnetic field. Cathode ray tubes with a perforated cathode can emit a glow from the end where the cathode is.
Erwin SchrodingerErwin Schrodinger was an Austrian physicist who helped contribute to quantum mechanics. He developed the Schrodinger equation which describes how the quantum state of a physical system changes over time. This equation has been universally celebrated as one of the most important achievements of the twentieth century, and a landmark in quantum mechanics,physics and chemistry.
James ChadwickChadwick proved the existence of neutrons. He defined neutrons as elementary particles devoid of any electrical charge. In contrast with the helium nuclei (alpha rays) which are charged, and therefore repelled by the considerable electrical forces present in the nuclei of heavy atoms, this new tool in atomic disintegration need not overcome any electric barrier and is capable of penetrating and splitting the nuclei of even the heaviest elements.