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Greek philosopher, Democritus, develop the idea of atoms.
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English chemist, John Dalton performed experiments with various chemicals that showed that matter, indeed, seem to consist of elementary lumpy particles (atoms).
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Max Planck, a professor of theoretical physics in Berlin showed that when you vibrate atoms strong enough, such as when you heat an object until it glows, you can measure the energy only in discrete units. He called these energy packets, quanta.
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Albert Einstein wrote a ground-breaking paper that explained that light absorption can release electrons from atoms, a phenomenon called the "photoelectric effect
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Ernest Rutherfod thought that the electrons must exist somewhere within this empty space. Rutherford thought that the negative electrons orbited a positive center in a manner like the solar system where the planets orbit the sun.
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Danish physicist, Niels Bohr came up with a theory that said the electrons do not spiral into the nucleus and came up with some rules for what does happen.
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Rutherford identified the particles of the nucleus as discrete positive charges of matter. He found the protons mass at 1,836 times as great as the mass of the electron.
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Paul Dirac produced equations which predicted an unthinkable thing at the time- a positive charged electron.
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English physicist James Chadwick finally discover the neutron. He found it to measure slightly heavier than the proton with a mass of 1840 electrons and with no charge (neutral).
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Werner Heisenberg concluded that charged particles bounce photons of light back and forth between them. This exchange of photons provides a way for the electromagnetic forces to act between the particles.
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in experiments with cosmic rays, Carl Anderson discovered the anti-electron, which proved Paul Dirac's equations. Physicists call it the positron.
