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The Alchemists created the operational criterion of an "atomic" element as the last point of analysis -
Plato theories that these solid forms of matter are composed of invisible elects shaped like triangles -
Democritus theorised that atoms were specific to the material which they composed -
Robert Boyle believe that all substances were made up of atoms -
Antoine Lavoisier discovered law of conservation of mass and that would help discover atomic theory. -
The Ballard Ball Model is when atoms could combine and recombine with each other in whole ratios to form compounds. -
John Dalton had an atomic theory suggested that all matter was compromised of invisible and indestructible atoms with distinct masses and properties -
Amedeo Avogadro suggested that equal volumes of all gasses at the same temperature pressure containing the same number of a molecule. -
Dmitri Mendeleev discovered the periodc law -
J.J. Thomson announced his discovery that atoms were made up of smaller components. -
Pierre and Marie Curie discovered the strong radioactive elements polonium and radium. -
Neils Bohr proposed a theory for the hydrogen atom, based on quantum theory on some physical qualities only discrete valves -
The Plum Pudding Model is a source positive charge within the atom to counter balance the negative charge. -
Albert Einstein mathematically predicted the size of both atoms and molecules -
Robert Milikan made an accurate determination of the charge carried by an electron using the elegant "falling drop method", therefore demonstrating the atomic structure of electricity. -
Ernest Rutherford described the atom as having a tiny, dense, and positive charged core called the nucleus. -
The Solar System Model describes atoms as consisting of a nucleus with a number of electrons in or bits around that nucleus. -
Henry G.J Mosley collected the x-ray spectra of a variety of elements and found that the frequency of x-ray radiation has a precise mathematical relationship to an elements atomic number. -
The Electron Cloud Model shows the area in space where an electron is most likely to be -
James Chadwick discovered the atoms consisted not only of protons and electrons but also nuetrons