ATOMS AND LINE SPECTRA PRELAB ASSIGNMENT Name

E-2EXPERIMENT E: ATOMS AND ELECTRONSPRELAB ASSIGNMENT (CONTINUED)2. Consider the lights used to control traffic in Edmonton: green, yellow and red. Arrange theselights in order of increasing energy. Explain why. No numeric calculation is needed. (0.5mark)3. Refer to Figure 7.8 on p. 301 of Zumdahl. The longest wavelength of Balmer series of thespectral lines for hydrogen (transitions to n=2) corresponds to the transition the n=3 to n=2levels. Explain in words why this might be expected. (no calculation needed). ( 1 mark )4. Eq (3) gives the energy (according to the Bohr model) of the energy levels available to anelectron in any hydrogen-like atom. Calculate the second ionization energy of He ( in J ).( 1 mark )

E-5(d) Record for helium, the colour and wavelength of the most intense of the lines (up to seven linesmight be observable). (0.5 mark)(e) Transitions of the electron between which levels (ie. the electron goes from m=? to n=? levels)might give photons of those wavelengths? (0.5 mark)(f) Describe the spectrum for neon. Record the colour and wavelength of some representativespectral lines covering the entire range of wavelengths of the spectrum. (0.5 mark)

E-6III. Flame TestsA burner is set up in the fumehood along with a number of metal salts. To carry out theFlame Test on the salts, you would1. clean the Pt wire by alternately dipping it into concentrated HCl and then heating it in thehottest part of the burner flame (use the burner set up in the fumehood for this purpose)until the wire gives little or no color to the flame. Repeat this several times until the wire isclean.2. bring the clean Pt wire to your bench top. Place a solid crystal of a salt on the clean wireloop, heat it in the Bunsen burner flame and observe any color in the flame.(a) Carry out the flame test for LiCl. Record your observations below. Repeat for the other salts.(1 mark)(b) Again, clean the Pt wire between each salt as decribed above. To check that all sodium hasbeen removed, after the flame seems clear check any light emitted from the flame using thespectroscope for any yellow/orange line at about 590 nm (which would be due to sodium). Becareful to keep the spectrometer well back of the flame.(c) With the assistance of another student, observe the line spectra of the flames for each of thesalts used in Part (a). Give both the colour and wavelength of the spectral lines. (2 marks)ASSESSMENTTurn in this Work Sheet at the end of the lab period. Your mark for this experiment will bebased on the Prelab Assignment ( 5 marks), and the Work Sheet ( 10 marks).