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John Dalton was the first person to develop a useful atomic theory. He discovered that chemical reactions can be expressed by the combining and separation of atoms and that these atoms have features to identify themselves.
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In 1897, J.J discovered the electron. He suggested that no matter where the material came from, it would contain particles that were smaller yet the same as the atoms that the material was found from.
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Marie CurieCurie discovered the radioactive elements polonium and radium in 1898. With the help of her husband, Pierre Curie, they found that these elements can cause atoms to break down voluntarily and release radiation in the form of subatomic particles and energy.
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He suggested the nuclear structure of an atom in 1911 and made model that described the atom as dense and tiny, with a positively charged care called a nucleus which is where most of the mass is.
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Niels discovered that the number of electrons in the outer orbit determines the properties of an elements and also that electrons travel in separate orbits around the nucleus.
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Henry Moseley discovered a way to accurately position elements in the periodic table by using x-rays in 1913. He was able to do this because he found that there was an orderly link between the wavelength and atomic number.
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Francis AstonAston was a chemist and physicist. In 1920, Francis invented the mass spectrograph and was the first person to observe isotopes. He found that there was actually three types of hydrogen atoms.
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Erwin developed a mathematical model for the dispensation of electrons in an atom by combining de Broglie equation with the equations of the behavior of waves in 1926. The model gives an estimate of where the electron can be found at a given time and in a particular space.
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In 1931 James discovered a way to measure the energy that comes out of the hydrogen atom and also proved the existence of neutrons. He confirmed that the atomic number is set on the number of protons in an atom.
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Murray discovered a quark, which is a fast moving point of energy. It makes up the protons and neutrons in the nucleus.
