68111040-1-3-bohrmodel - Bohr Atom In 1911, Rutherford...

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Bohr Atom In 1911, Rutherford introduced a new model of the atom in which cloud of negatively charged electrons surrounding a small, dense, positively charged nucleus. This model is result of experimental data and Rutherford naturally considered a planetary-model atom. The laws of classical mechanics (i.e. the Larmor formula, power radiated by a charged particle as it accelerates.), predict that the electron will release electromagnetic radiation while orbiting a nucleus. Because the electron would lose energy, it would gradually spiral inwards, collapsing into the nucleus. This atom model is disastrous, because it predicts that all atoms are unstable. To overcome this difficulty, Niels Bohr proposed, in 1913, what is now called the Bohr model of the atom . He suggested that electrons could only have certain classical motions: 1. The electrons can only travel in special orbits: at a certain discrete set of distances from the nucleus with specific energies. 2. The electrons of an atom revolve around the nucleus in orbits. These orbits are associated with definite energies and are also called energy shells or energy levels. Thus, the electrons do not continuously lose energy as they travel in a particular orbit. They can only gain and lose energy by jumping from one allowed orbit to another, absorbing or emitting electromagnetic radiation with a frequency ν determined by the energy difference of the levels according to the Planck relation : 3. Kinetic energy of the electron in the orbit is related to the frequency of the motion of
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This note was uploaded on 01/12/2012 for the course CHEM 133 taught by Professor Staff during the Spring '08 term at UCSD.

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68111040-1-3-bohrmodel - Bohr Atom In 1911, Rutherford...

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