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John Dalton
In 1803 John Dalton proposed an "Atomic Theory."-All Matter is made of atoms, all atoms of an element must be the same, two or more different kinds of atoms from compounds and a rearrangement of atoms is a chemical reaction. -
Marie Curie
Marie Curie found out that the strength of the radiation did not depend on the compound that was being studied. It depended only on the amount of uranium or thorium. What was decisive for the radiation they gave off was only the amount of uranium they contained. Marie drew the conclusion that the ability to radiate did not depend on the arrangement of the atoms in a molecule, it must be linked to the interior of the atom itself. -
J.J thomson
Determined the charge to mass ratio of an electron with a CRT -
Ernest Rutherford
Ernest Rutherford established that the nucleus was very dense,very small and positively charged, he also found out that the electrons were located outside the nucleus, This was found out by using alpha particles as atomic bullets, probed the atoms in a piece of thin gold foil. -
Henry Mosely
He developed the application of X-ray spectra to study atomic structure. Moseley's discoveries resulted in a more accurate positioning of elements in the Periodic Table. -
Erwin Schrodinger
Erwin proposed that electrons are arranged in concentric circular orbits around the nucleus. This model is patterned on the solar system and is known as the planetary model. -
Francis Aston
Francis Aston invented the mass spectrograph. He was the first person to observe isotopes. -
Niels Bohr
He Explained the atomic structure that underlies regularities of the periodic table of elements. He built an atomic model it had atoms built up of successive orbital shells of electrons -
James Chadwick
James Chadwick discovered the neutron using alpha particles. He used the Alpha particles and discovered a neutral atomic particle with a mass close to a proton. -
Murray Gell-Mann
Murray Gell-Mann showed scientists what makes up protons and neutrons, quarks.
