The term atom was coined by the Greek philosopher Democritus, around 460 B.C. Being a philosopher he proposed the question “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 it no further?” . He thought that at some point matter would become too small to divide again-this basic matter particle was what he called an atom. Democritus’ idea was dismissed by other Greek philosophers, including Aristotle who opted to replace it with the idea of four elements; water, fire, earth and air, of which everything else was composed. This theory is now known as the classical elements For the next 2000 years the idea of atoms were left unexplored. During the industrial revolution in the 1800’s, an English chemist-John Dalton- experimented with various chemicals proving that matter consisted of “elementary lumpy particles” (atoms) that were like “tiny, hard balls”. The next atomic model, the plum-pudding model, was developed by J.J. Thomson in 1897 after discovering the electron. He knew that electrons have a negative charge, from his experiments with cathode ray tubes, and so postulated that matter must have a positive charge. His model was called the plum-pudding model as it resembled the plums sticking out of a lump of plum pudding. When you vibrate atoms quickly enough, such as heating an object until it glows, you can measure the energy in distinct units called quanta; this was shown by Max Planck in 1900, a professor of theoretical physics in Berlin. Albert Einstein, using this information showed that the quanta behaved distinctly like particles. Einstein’s distinct light particle was called a “photon” (coined by Gilbert N. Lewis on December 18, 1926 in an article in the scientific journal Nature). This lead to a debate over whether light was a wave or a particle, with strong arguments for both cases. Physicists later showed that light could either be a wave or a particle...
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