Question

3. Besides H, list other hydrogen like species in which the Rydberg constant in eq. 3 would still be 1.10 x 10"? 4. Is a Het 5-3 transition in the visible range? Calculate and explain. 5. Are there any electronic transitions of Het involving energy levels 1, 2 and 3 which are in the visible range? That is, will He emit any visible photons when the electrons fall from any level to levels 1, 2, and 3? If not, show why. If so, cal- culate the wavelengths in A for the visible photon(s) and the approximate color of each photon. 6. Suppose that in another universe the laws have the same form but the con- stants are different. Calculate the Rydberg constant (cm-?) in that universe if a Li ion undergoing a transition from n = 6 to n = 5 emits a photon having a wavelength of 7000 A. Assume that the speed of light is the same as in this uni. verse. 7. Suppose that a student had performed the experiment and calculations per- fectly except for the following. Unknown to the student, the diffraction grating! was mislabeled so that the true rating (in lines per cm) were less than the la- bel indicated. Would the student's calculated value for the energy of the yellow line of mercury be equal to higher than, or lower than the true value? 8. If the diffraction grating were rated at 300 grooves per mm, then how many grooves per cm would that be? 9. If the diffraction grating from problem 8 were used and the b value from the ex- periment was 100.0 cm and the a value was 33.9 cm; then calculate the wave length observed in A units. 10. If the scale reading of a wavelength was found to be 3.00 in the spectroscope (using the Helium Spectrum calibration graph found in the calculations sec- tion), then: a) calculate the wavelength in Å and cm, b) calculate the frequency, c) calculate the energy in ergs, and d) determine the color of the wavelength.

Answer 1

For. He", z=2 = 5 9 x 25 X 23 3. The species is D (deueteriem iH?) 4. We have - $=(1.10X10°) zuha inte) Pay ny = 3 = (1-10x10°)x23x (2-)cm! = wavelength of = 1.10X10°x4 * 16ennis 1. emitted light or à = 9x25 1010x105x4x6 --em = 3.196x10 em = 3.196x10'm The range of wave length for visible light is 4.0 x10 m to ... 70x107m. so the above transition will not fall in - visible region. 5. For transition 2701 Erioxid 21 ian' - 1.10x10x6x3 em ="10x10°x2 x (2-bz) em =- ūce ora = 1 m = 3.03x10 m = 30.3 Å For transition 3701, = 105X1024 x Cashem! omnem = 2:56x10cm 101x15x4X8" = 256 Å For transition 3't02, = 1.10X105x4 (2-3) eu! . xxo or ^ = Ti 10x105x4x5 so, none of the transition will fall in visio 6. š = R'xz3 Chien tot Here, 1 = 7000 $ = 7000 XTZ EUA Z = 3 (for Li 2+) or 7000x138 =R *33(2-) ny =6, nx=5 or R = _ 25x36 el R=Rydberg constant 7000x 108 x 9X11 = 129870 cu'=l. 30x10 eu! ... Rydberg constant = 1.30x105 eu' cans) 5 14x5 cm zloben ible region. = 164 Å