Question

1. The figure below illustrates two electron transitions for a hydrogen atom. The transitions are labeled (a) and (b) in the figure. Energy n = 3 - n = 2 1 n = 1 Based on the figure alone (without performing any calculations) decide which of the transitions is associated with a lower wavelength. Briefly explain your reasoning.

Answer 1

1. The figure below illustrates two electron transitions for a hydrogen atom. The transitions are labeled (a) and (b) in the figure. Energy n = 3 - n = 2 1 n = 1 Based on the figure alone (without performing any calculations) decide which of the transitions is associated with a lower wavelength. Briefly explain your reasoning. If we observe carefully the figure, moore energy change takes place during the transition from 3----->7. But, Energy is inversely proportional to wavelength of the transition. The transition 3---------> 7 is associated with lower wavelength.

2. For the transition (a), the lower energy level is 3 and the higher energy level is 7

wave length of the transition is given by Balmer-Rydberg equation,

   1/$\lambda$= R_H [1/n²_low -1/n²_high] = 109,737.3 *(1/3²-1/7²) = 109,737.3 *(1/9-1/49) = 9953.49

wavelength corresponding to the transition (a), $\lambda$ a = 1/9953.49 = 0.0001004 cm

Energy of the transition (a) for 1 mole of electrons, Ea = Nhc/$\lambda$ = 6.023*10²³*6.625*10^-34*3*10⁸/(0.0001004*10^-2)

                                                                                  = 119 KJ/mole