Question

12(b). (i) Explain the term ionization potential. (ii) Using the energy level diagram shown (n=1 to n=∞, with given energies in eV), calculate the ionization potential of the hydrogen atom, given the transition from n=3 to n=1 emits a photon of wavelength 1.02×10⁻⁷ m.

Accepted Answer

(i) Ionization potential is the minimum energy required to remove the most loosely bound electron from an atom in its gaseous (ground) state.
(ii) Energy of transition ΔE=hc/λ = (6.6×10⁻³⁴×3×10⁸)/(1.02×10⁻⁷) = 1.94×10⁻¹⁸ J = 12.13 eV. Since ΔE=E₃-E₀ and E₃=-1.5 eV (from the diagram), E₀ = E₃-ΔE = -1.5-12.13 = -13.63 eV. The ionization potential is therefore 13.63 eV (magnitude of E₀).

WAEC Physics 2021 Theory — Question 28

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