2.

2. Answer the following questions regarding light and its interactions with molecules, atoms and ions.

(a) The longest wavelength of light with enough energy to break the Cl-Cl bond in Cl₂(g) is 494 nm.

(i) Calculate the frequency, in s^-1, of the light.

(ii) Calculate the energy, in J, of a photon of the light.

(iii) Calculate the minimum energy, in kJ mol^-1, of the Cl-Cl bond.

(b) A certain line in the spectrum of atomic hydrogen is associated with the electronic transition in the H atom from the sixth energy level (n = 6) to the second energy level (n = 2).

(i) Indicate whether the H atom emits energy or whether it absorbs energy during the transition. Justify your answer.

The n = 6 state is higher in energy than the n = 2 state. Going from a high energy state to a low energy state means that energy must be emitted.

(ii) Calculate the wavelength, in nm, of the radiation associated with the spectral line.

(iii) Account for the observation that the amount of energy associated with the same electronic transition (n = 6 to n = 2) in the He⁺ ion is greater than that associated with the corresponding transition in the H atom.

The positive charge holding the electron is greater for He⁺, which has a 2+ nucleus, than for H with its 1+ nucleus. The stronger attraction means that it requires more energy for the electron to move to higher energy levels. Therefore, transitions from high energy states to lower states will be more energetic for He⁺than for H.

2. Answer the following questions regarding light and its interactions with molecules, atoms and ions.

(a) The longest wavelength of light with enough energy to break the Cl-Cl bond in Cl2(g) is 494 nm.

(i) Calculate the frequency, in s-1, of the light.

(ii) Calculate the energy, in J, of a photon of the light.

(iii) Calculate the minimum energy, in kJ mol-1, of the Cl-Cl bond.

(b) A certain line in the spectrum of atomic hydrogen is associated with the electronic transition in the H atom from the sixth energy level (n = 6) to the second energy level (n = 2).

(i) Indicate whether the H atom emits energy or whether it absorbs energy during the transition. Justify your answer.

The n = 6 state is higher in energy than the n = 2 state. Going from a high energy state to a low energy state means that energy must be emitted.

(ii) Calculate the wavelength, in nm, of the radiation associated with the spectral line.

(iii) Account for the observation that the amount of energy associated with the same electronic transition (n = 6 to n = 2) in the He+ ion is greater than that associated with the corresponding transition in the H atom.

(a) The longest wavelength of light with enough energy to break the Cl-Cl bond in Cl₂(g) is 494 nm.

(i) Calculate the frequency, in s^-1, of the light.

(iii) Calculate the minimum energy, in kJ mol^-1, of the Cl-Cl bond.

(iii) Account for the observation that the amount of energy associated with the same electronic transition (n = 6 to n = 2) in the He⁺ ion is greater than that associated with the corresponding transition in the H atom.