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John Dalton
John Dalton created the theory that all matter is made up of indivisible atoms, all atoms of an element are identical and atoms are neither created nor destroyed. -
Michael Faraday
Michael Faraday composed the theory when he found a solution to the problem of producing continuous rotation by use of electric current, thus making electric motors possible. -
Johannes Hittorf
Johannes Hittorf found that when a solid object was placed between the cathode and anode, a shadow was cast on the end of the tube across from the cathode. -
William Crookes
William Crookes developed a better vacuum pump that allowed him to produce cathode-ray
tubes with a smaller residual gas pressure. -
William Conrad Roentgen
William Conrad Roentgen discovered x-rays while using cathode-ray tubes. He also found that x-rays could pass
through solid objects. -
J.J. Thompson
J.J. Thompson found that cathode rays could be deflected by an electric field and showed that cathode "rays" were actually particles. His conclusion was that particles were a universal component of matter. -
Ernst Rutherford
Ernst Rutherford updated Thomson's Raisin Pudding Model of the atom. Also to conclude his other expirements, he found out that the positive charge and mass of an atom were concentrated in the center and only made up a small fraction of the total volume. He named this concentrated center the nucleus (Latin for little nut). -
Robert Millikan
Milikan discovered the charge of the elctron which is 1.60 x 10-19. He also confirmed Albert Einstein's theory of the photoelectric effect. -
H. G. J. Moseley
He found that atoms of each element contain a unique positive charge in their nucleus. This discovery helped to solve the mystery of what makes the atoms of one element different from those of another: An atom's identity comes from the number of protons in its nucleus. -
James Chadwick
He proved that neutrons, neutral particles in the nucleus that made up approximately
half the mass of an atom, did exist. -
A. van den Broek
A. van den Broek suggested that the positive charge on atoms should be compared to their atomic numbers, not their atomic weights.
