Chapter 3: Problem 4
Show that if we add a constant to all of the energies in hydrogen, the energies of the various transitions are unaffected.
Short Answer
Expert verified
Adding a constant to all energy levels does not change the transition energies.
Step by step solution
01
- Understand Hydrogen Energy Levels
The energy levels in a hydrogen atom are given by the formula: \( E_n = - \frac{13.6 \text{ eV}}{n^2} \) where \( n \) is a positive integer representing the principal quantum number.
02
- Adding a Constant to Energy Levels
Suppose we add a constant \( C \) to all energy levels: \( E_n' = E_n + C \). This means the new energy level for any state \( n \) becomes \( E_n' \).
03
- Calculate Transition Energy with Constant
The energy of a transition between two levels \( n_1 \) and \( n_2 \) (with \( n_1 < n_2 \)) is given by \( \Delta E = E_{n_2} - E_{n_1} \). With the added constant, this becomes: \( \Delta E' = E_{n_2}' - E_{n_1}' \). Substitute in the modified energy levels: \( \Delta E' = (E_{n_2} + C) - (E_{n_1} + C) \)
04
- Simplify the Expression
After substitution, the expression simplifies to: \( \Delta E' = E_{n_2} - E_{n_1} + C - C \). The terms involving \( C \) cancel out: \( \Delta E' = E_{n_2} - E_{n_1} \)
05
- Conclusion
Notice that \( \Delta E' \) (the transition energy with the added constant) is equal to \( \Delta E \) (the original transition energy) since the constant \( C \) cancels out. Hence, the energies of the transitions are unaffected by the addition of a constant.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
energy transitions
Energy transitions are a key concept in atomic physics, particularly for hydrogen atoms. An energy transition occurs when an electron moves between two energy levels. These levels are quantized, meaning electrons can only exist in certain discrete energy states. An electron emits or absorbs a photon when it transitions from a higher energy level to a lower one or vice versa. The energy of the photon corresponds to the difference between these energy levels, which is calculated as: \( \Delta E = E_{n_2} - E_{n_1} \). This means that the energy change (\( \Delta E \)) depends solely on the electronic levels involved. Adding a constant to all energy levels does not change this difference, hence the transition energy remains the same.
quantum mechanics
Quantum mechanics is the framework that explains the behavior of particles at microscopic scales. It particularly describes how electrons inhabit discrete energy levels in atoms. Unlike classical mechanics, where particles can have any energy, quantum mechanics restricts energies to specific values. The energy of an electron in a hydrogen atom is dictated by formulas derived from quantum mechanics. One such formula for hydrogen is: \( E_n = - \frac{13.6 \text{ eV}}{n^2} \). The negative sign indicates that the electron is bound to the nucleus. Any changes in the energy levels, such as adding a constant, do not alter the fundamental quantum mechanical principles or the transition energies.
principal quantum number
The principal quantum number, symbolized as \( n \), is a fundamental concept in quantum mechanics. It indicates the main energy level an electron occupies and can be any positive integer (1, 2, 3, ...). Larger values of \( n \) correspond to higher energy levels further from the nucleus. The energy level formula for hydrogen is: \( E_n = - \frac{13.6 \text{ eV}}{n^2} \), where \( E_n \) gets less negative (higher energy) as \( n \) increases. Understanding \( n \) is crucial for calculating energy transitions. The difference in energy levels between two states \( n_1 \) and \( n_2 \) determines the transition energy, not the absolute energy values themselves.
constant addition in energy levels
Adding a constant to all energy levels means each energy level is increased by the same amount. In the case of hydrogen, the energy levels are initially given by \( E_n = - \frac{13.6 \text{ eV}}{n^2} \). If we add a constant \( C \): \( E_n' = E_n + C \). For any two energy levels \( n_1 \) and \( n_2 \), the energy transition is: \( \Delta E = E_{n_2} - E_{n_1} \). With the added constant: \( \Delta E' = (E_{n_2} + C) - (E_{n_1} + C) = E_{n_2} - E_{n_1} \). Thus, the constant cancels out, showing that the transition energies remain unaffected by the constant addition. This demonstrates the relative nature of energy measurements in quantum systems.