Question

Difficulty: MediumAtomic Models

In a hydrogen atom modeled according to Bohr's theory, an electron undergoes a transition from an excited state with an energy of 1.51 eV-1.51\text{ eV} to a lower energy state of 3.40 eV-3.40\text{ eV}. Calculate the energy of the emitted photon in electron-volts (eV\text{eV}).

Answer: 1.89 eV

Answer

The energy of the emitted photon is 1.89 eV1.89\text{ eV}.
According to Bohr's atomic model, when an electron drops from an initial higher energy level EiE_i to a final lower energy level EfE_f, a photon is emitted carrying energy E=EiEfE = E_i - E_f. Substituting the given values gives E=1.51 eV(3.40 eV)=1.89 eVE = -1.51\text{ eV} - (-3.40\text{ eV}) = 1.89\text{ eV}.

Step-by-Step Solution

1
Identify the initial and final energy states of the electron.
Ei=1.51 eVE_i = -1.51\text{ eV} and Ef=3.40 eVE_f = -3.40\text{ eV}.
The electron moves from a higher (less negative) energy state to a lower (more negative) energy state.
2
Apply Bohr's energy quantization formula for photon emission Ephoton=EiEfE_{\text{photon}} = E_i - E_f.
Ephoton=1.51(3.40)=1.89 eVE_{\text{photon}} = -1.51 - (-3.40) = 1.89\text{ eV}.
By energy conservation, the energy lost by the transitioning electron equals the energy of the emitted photon.

Key Concept

Bohr's Energy Transition Postulate
Estimated Time:1m 0s
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