Democritus, who discovered the atom in 442 BC, claimed that it was an unbreakable, indivisible unit. Democritus was the first to postulate the existence of the atom, but it wasn't until John Dalton in 1803 that a scientist was able to actually examine and define what the atom was.

Dalton deserves the majority of the credit because he dissected the atom and could explain what each component did, but Democritus would not have known about the atom if it weren't for Dalton.

When Goldstein was working with the cathode-ray tube, he noticed that some of the rays were moving in the opposite direction from the cathode rays and gave them the name proton. Field hockey is a historical finding that was made during Goldstein's discovery of the proton and is still used in modern life.

While conducting an experiment in which he passed electric current through gases at low pressure, Thomson made the discovery of the electron. Thomas Edison found a way to patent the motion picture camera during his work on the electron, or during his work on the electron he found a way to patent the motion picture camera.

In order to conduct an experiment to determine the amount of an electron's charge in 1910, Millikan used an oil drop experiment. The oil droplets in this experiment would fall at various rates as he altered the voltage.

Rutherford sought to put the plum pudding theory of atomic structure to the test in 1911. He devised the Gold Foild Experiment as a result. It would fire an alpha particle beam against a tiny piece of gold foil; some of the particles would pass through, but some would bounce. This occurred as a result of the particles striking the nuclei. A tiny central core of an atom called the nucleus is composed of protons and neutrons.

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Rutherford determined that the nucleus was what was deflecting the apha particles in his 1911 Gold Foil experiment. According to him, an area with sufficient positive charge will deflect alpha particles. But it wasn't until Chadwick that the existence of neutrons was discovered.

According to Borhr's model of the electron from 1913, they orbit the nucleus in a circle at a set distance. He said that the fixed energy known as energy levels is present in these orbiting electrons.

The electrons in the image are circulating outside of the nucleus and are capable of changing energy levels.

in 1932, James Chadwick confirmed that that there was another subatomic particle called the Neutron. He discovered that the neutron was a subatomic particle with no charge but with mass nearly equal to the protons.

Maria published her paper with extensive support for the nuclear shell, which would account for the characteristics of atomic nuclei, in August of 1948.

She was one of two women to get the physics nobel award.