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• In 460BC, the Greek philosopher Democritus developed the idea of atoms. He was quite a curious man and wondered, if you break a piece of matter in half, and then break it in half again, how many breaks will you have to make before you can break the atom no further? Democritus believed that “it ended” at some point. That there was a smallest possible bit of matter. Democritus called these basic matter particles, atoms.
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In the early 1800’s, John Dalton, an English chemist, performed experiments with various chemicals which showed that matter, seemed to consist of elementary lumpy particles, also known as atoms. Although he did not know about their structure, he knew that the evidence pointed to something that was fundamental.
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In 1897, an English physicist known as J.J Thomson discovered the Electron and proposed a model of the structure of the atom. Thomson had known that electrons had a negative charge and believed that matter must have a positive charge.
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In 1900, a professor of Theoretical physics living in Berlin known as Max Planck, showed, that when you vibrate atoms strong enough, for example when heating an object till it glows, you can measure the energy, but only in discrete units. He called these energy packets, quanta.
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In 1900, Eugen Goldstein discovered protons in Anode Ray experiments. According to Eugen, atoms contain positively charged particles called protons. Since atoms contain negatively charged particles, they must contain positively charged particles for them to be electrically neutral.
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In 1905, Albert Einstein had published the famous equation “E=MC 2." The equation tells us that the amount of energy of an object would be equivalent to it’s mass.
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In 1911, Ernest Rutherford discovered the nucleus and provided the basis for the modern atomic structure. Ernest achieved this through his alpha particle scattering experiment. Ernest believed that atoms are made of two parts: The nucleus and the extra-nuclear part. His experiments, had proved that the atom is largely empty and has a heavy positively-charged body at the centre called the nucleus.
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In 1932, James Chadwick discovered neutrons. According to James, atoms contain neutral particles known as neutrons in in the atom nucleus along with the subatomic particles.
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In 1940, Niels Bohr provided the modern concept of the atomic model. From Bohr’s research, the atom is believed to be made of a central nucleus containing protons and neutrons. The electrons revolve around the nucleus in different imaginary paths called orbits or shells.
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In 1942, Enrico Fermi conducted the first controlled chain creation releasing energy from the atoms nucleus.
