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Describe how Bohr used line emission spectra to explain the existence of energy levels in atoms - Leaving Cert Chemistry - Question b - 2004
Question b
Describe how Bohr used line emission spectra to explain the existence of energy levels in atoms. Why does each element have a unique line emission spectrum? The fa... show full transcript
Worked Solution & Example Answer:Describe how Bohr used line emission spectra to explain the existence of energy levels in atoms - Leaving Cert Chemistry - Question b - 2004
Step 1
Describe how Bohr used line emission spectra to explain the existence of energy levels in atoms.
Answer
Niels Bohr proposed that electrons in an atom occupy fixed energy levels. These levels are quantized, meaning that only certain energies are allowed. When an electron in its ground state absorbs energy, it can jump to a higher energy level, becoming unstable. The electron will then fall back to a lower energy level, emitting energy in the form of light, which manifests as discrete wavelengths in the line emission spectrum.
Bohr illustrated this with an energy level diagram, showing the specific energies and transitions. The frequency of light emitted corresponds to the energy difference between the two levels, determined by the equation:
u $$ where $E$ is the energy, $h$ is Planck's constant, and $\nu$ is the frequency of the emitted light.Step 2
Why does each element have a unique line emission spectrum?
Answer
Each element has a unique electron configuration, which determines the arrangement and distribution of its electrons among energy levels. This distinct distribution leads to different electron transitions when an electron moves between energy levels. As a result, each element emits a unique set of wavelengths, creating its own characteristic line emission spectrum. Hence, the variation in energy levels and their associated transitions gives rise to different spectral lines.
Step 3
Step 4
Give one reason why this theory was updated.
Answer
Bohr's atomic theory was modified due to its inability to explain certain phenomena, such as the Zeeman effect, which involves the splitting of spectral lines in a magnetic field, and the wave-particle duality of electrons, which was later incorporated into quantum mechanics.