Bohr's Model


Rutherford's model is much like our current generic atomic model, minus the neutrons (discovered through more experiments). Like all atomic models in the past, Rutherford's model had just one flaw. The electrons in his model were doomed to fall out of their orbit around the nucleus and collapse into the nucleus, annihilating the atom. To make a long decade short, Neils Bohr fixed Rutherford's problem with a little imagination.
In his atomic model, the electrons were located in different energy levels, where each energy level was further from the nucleus (which now had neutrons as well as protons) than the previous. For example, if the first energy level was one inch away from the nucleus, the second would be two inches away, the third would be four, the fourth would be eight inches away, and so on. Bohr's energy levels cannot have a energy between two levels though. The electron is much like a ball resting on the stairs. If you give it enough energy, it will go up to the next step. If not enough energy is provided, it will not go halfway between the steps, for there is nowhere for it to rest there. Any excess energy is given off as light. Also, if the ball goes up a step, there will be room on the lower steps for it, and since the arrangement with the lowest energy is always the most stable, it's pretty likely that the ball/electron will give off some light and fall back down to it's old step. Bohr's model solved the problem of Rutherford's decaying orbits, but it was an incomplete solution. Unlike balls on steps, electrons can't just sit there. There had to be some movement to oppose the attraction between the positive and negative charges. This problem is solved by the quantum atomic model.

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