Final answer:
When an electron moves from a lower to a higher energy level within an atom, it absorbs a photon corresponding to the energy difference between the two levels. This concept is integral to the Bohr model of the atom and can be observed in the spectral lines of elements.
Step-by-step explanation:
Understanding Electron Transitions and Photon Interactions
When an electron moves from a lower to a higher energy level, the electron absorbs a photon. This process is crucial in understanding the behavior of electrons within atoms and is foundational to atomic physics and quantum mechanics. In the context of the Bohr model of the atom, if an electron wants to ascend to a higher energy level, it absorbs energy in the form of a photon. The energy of the photon must match the energy difference between the two levels. Conversely, when an electron falls from a higher energy level to a lower one, it emits a photon carrying away the excess energy.
The emission or absorption of photons by atoms can be observed in spectral lines, with each transition corresponding to a specific photon energy (and, therefore, a specific wavelength). For example, the Balmer series represents transitions where electrons fall from higher energy levels to the second energy level, emitting photons of specific wavelengths that are visible to the human eye. On the other hand, when discussing electron capture, a positively ionized atom attracts free electrons to become neutral again, emitting photons during the process.
In summary, the correct answer to the student's question is that when an electron moves to a higher energy level, it absorbs a photon (b).