How have your ideas about atoms changed over time?

Answer 1

The Greek Democritus proposed that matter had a limit to how finely it could be "cut" by a sharp knife. He named these "a-tomos" which literally means "un-cuttable" and is the root source of the modern word "atom". The Hindus also offered an atomic theory. Aristotle rejected "a-tomos" and held that any "minima" portion of substance could always be reduced. Classical Atomists could never develop a reasonable theory of how atoms joined together to form the objects we observe in the Universe. But in chemistry, the "atomic" nature of matter was being firmly established by experimentation. When it became obvious that electrons and alpha particles were related to atoms, various new electrical models were put forth -- including a positive pudding with negative raisin "electrons" theory, and a solar system theory where electrons orbited a positive nucleus like planets in the solar system. Quantum "wave" theory has developed the best atomic model so far and has supplanted all older classical models. Atoms en masse were first observed using electron microscopes; and the first actual capture and observation (using lasers) of single atom (of Boron) occurred in 1996.