E3 = -(13.6/32) eV = -1.51 eV E2 = -(13.6/22) eV = -3.40 eV QUESTION: According to Bohr’s model, what is the energy of the photon released when an electron jumps from the third orbit to the second orbit of the hydrogen atom? A. 13.6 eV, B. 1.89 eV, C. 10.2 eV, D. 2.27 eV According to Bohr: E photon = E higher orbit - E lower orbit E for orbit n = -(13.6 eV) / n2 E3 = -(13.6/32) eV = -1.51 eV E2 = -(13.6/22) eV = -3.40 eV Therefore: E photon = -1.51 eV – (-3.40 eV) = 1.89 eV SCRIPT According to Bohr’s model, what is the energy of the photon released when an electron jumps from the third orbit to the second orbit? A. 13.6 eV, B. 1.89 eV, C. 10.2 eV, D. 2.27 eV PAUSE CLICK According to Bohr, an atom releases one photon of light when an electron goes from a hydrogen atom. The energy of the photon produced is equal to the difference in the energies associated with the orbits. For the hydrogen atom, Bohr derived the energy of the an electron in the nth orbit to be -13.6 electron volts, divided by n squared CLICK In this problem, we are given that the electron jumps from the third orbit to the second orbit. So we calculate E for the third orbit… -13.6 electron volts, divided by 3 squared,… equals –1.51 electron volts… And we calculate E for the second orbit… -13.6 electron volts, divided by 2 squared… equals –3.40 electron volts CLICK The energy difference, …. –1.51 electron volts, minus –3.40 electron volts, … equals 1.89 electron volts Here’s a diagram to help you visualize this calculation. The energy of the electron in the third orbit is –1.51 electron volts. CLICK When it jumps to the second orbit, CLICK it loses energy and ends up with –3.40 electron volts. The amount of energy lost, delta E, is –1.51 electron volts minus –3.40 electron volts, or 1.89 eV CLICK 1.89 electron volts of energy is carried away by a photon. This explains the red light, with a wavelength of 656 nm, that is produced by a hydrogen lamp. CLICK CLICK The series of lines produced by hydrogen in the visible region is known as the Balmer series. Bohr explains these lines as due to transitions of electrons to the second orbit from higher orbits. The red line corresponds to the transition from the third orbit. The blue line corresponds to transition from the fourth orbit. The PAUSE END RECORDING

                                                                             } E= -1.51 eV E = -1.89 eV E= -3.40 eV 656 nm

Video ID: 2-2-4 © 2008, Project VALUE (Video Assessment Library for Undergraduate Education), Department of Physical Sciences Nicholls State University Author: Glenn V. Lo Funded by Louisiana Board of Regents Contract No. LA-DL-SELECT-13-07/08