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The Ancient Greeks believe all matter was formed from 4 fundamental elements: fire, water, earth and air. The very beginning theory of what the world was made off.
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Democritus suggested that all matter was made up of tiny, indestructible particles, dubbed "atomos" meaning, "indivisible". He described atoms as minuscule quantities of matter, in the shape of solid balls.. Though he took credit for the atomic theory, the first prediction of its kind, it was actually derived from his mentor's theory.
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Aristotle’s theory made a great generalisation of all matter of the four elements: fire, water, earth, and air. He also believed that there were four qualities to these elements: dryness, hotness, coldness, and moistness. Though Democritus' theory was potent at the time, Aristotle still preached his theory, convincing many.
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Dalton proposed that all matter was made up of hard indivisible spheres.
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After discovering the negatively charged electron in 1897, Dalton proposed that atoms were positively charged spheres with electrons in it, like plums in a pudding.
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Hungarian scientist, Phillip Lenard describes atoms as heavy positively charged particles stuck to a light negatively charged particle, later proved incorrect.
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Scientist, Ernest Rutherford discovered that atoms consisted of a small positively charged nucleus surrounded by a large space of electrons. He did this by firing alpha particles through a thin sheet of gold, observing that some particles bounced back, but the rest went through the sheet. The few particles that bounced back, hit the nucleus. The rest went through the electron clouds.
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Niels Bohr, modified Rutherford's model, proposing that the electrons orbited around the nucleus, like satellites orbiting around a planet.
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Scientist, James Chadwick discovers the neutron, proposing that the nucleus was composed of proton with a positive charge and neutrons with a neutral charge.
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Scientists now believe that electrons revolve around the nucleus in a specific clouds rather than orbits. The shape of electron clouds can be predicted but not the exact location of the electron.
