![]() Bohr did so and soon had the answer for how the lines are produced. Hansen disputed Bohr's position and insisted Bohr look up Balmer's work. No one, and I mean no one, had any answers for what was going on.) (Remember that by 1913, several thousand lines, of different elements, were known AND many of these lines exhibited bizarre splittings - called the Zeeman effect - in magnetic fields. Bohr's reply was that he had not seriously considered the issue, believing the answer to be impossibly complex. It was probably here (in the first week of February 1913) that (according to Bohr's recollection in 1954) he was asked by Hans Marius Hansen (a yound Danish physicist) how Bohr's new atomic model would explain the hydrogen spectrum. The letter shows Bohr HAD been thinking about spectra. The next event in this story (which is not the complete one, only highlights) is a Januletter to Rutherford in which Bohr excluded the "calculation of frequencies corresponding to the lines of the visible spectrum." However, the paper Bohr mailed to Rutherford on Macontained the correct mechanism for the production of the lines of the spectrum. This slowed down the work on the atomic model paper, but it was not abandonded. He wrote a note to Rutherford on Novemapologizing for the time he was taking "to finish my paper on the atoms and send it to you." By January 1913, Bohr and his wife were back in Copenhagen where he assumed his new position as assistant to the physics professor. Bohr finished that work and eventually the term ended, ending Bohr's year-long government grant for study.īohr even fell behind schedule in writing the paper I am discussing. The new term was beginning and Bohr was behind schedule in finishing some work that Rutherford had assigned to him. He and his wife did not honeymoon in Norway as planned, but returned more-or-less immediately to Manchester. At least, I think so.īohr was married, as I said, in August, 1912. The story surrounding this is interesting. Two paragraphs later, in referring to "monochromatic radiation," he uses the phrase "discontinuous medium consisting of energy quanta."įeature #4 above is Bohr's explanation of the mechanism for the production of lines in the hydrogen spectrum. Monochromatic radiation of low density behaves - as long as Wein's radiation formula is valid - in a thermodynamic sense, as if it consisted of mutually independent energy quanta. By analogy, then, energy could be treated the same way as a gas - as a collection of particles moving around within the volume. He wound up showing that certain equations governing energy behavior are exactly the same as those for a gas in the same volume. In 1905, Albert Einstein wrote an article in 1905 titled "On a Heuristic Point of View about the Creation and Conversion of Light." In it he uses Planck's idea of a quantum to explain something called the photoelectric effect. It SEEMS like a steady, unbroken stream of gas, but in reality it is trillions and trillonsof individual gas molecules all moving in the same direction. Still another example is a stream of gas shooting out a nozzle. The idea is the same with the energy quantum. It SEEMS like a steady, unbroken stream of water, but we know it is just trillions and trillions of tiny, individual water molecules. ![]() Each bullet is a "quantum."Īnother example is water coming out of a hose. It SEEMS like a stready, unbroken stream of metal, but it is not. One way to think about the quanta of energy streaming out is to think of a machine gun shooting out thousands of bullets per second. So a quantized atom being stimulated is shooting out trillions of quanta (plural) of energy per second. The term "quantum" was introduced by Planck to describe a small bundle of energy. Today, we call this model an example of a "quantized" atom. The Bohr model has the following features:ġ) There is a nucleus (this was Rutherford's discovery).Ģ) The electrons move about the nucleus in "stationary states" which are stable, that is, NOT radiating energy.ģ) When an electron moves from one state to another, the energy lost or gained is done so ONLY in very specific amounts of energy, not just any old amount.Ĥ) Each line in a spectrum is produced when an electron moves from one stationary state to another. What exactly is the Bohr Model of the Atom? ChemTeam: The Bohr Model of the Atom The Bohr Model of the Atom ![]()
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