What wavelength(s) appear(s) in the atom’s emission spectrum?
Express your answer in nanometers. If there is more than one answer, enter your answers in ascending order separated by commas.
What wavelength(s) appear(s) in the atom’s absorption spectrum?
Express your answer in nanometers. If there is more than one answer, enter your answers in ascending order separated by commas.
The Correct Answer and Explanation is:
To determine the wavelength(s) that appear in an atom’s emission and absorption spectra, we need to understand how electrons in atoms interact with energy.
Correct Answer (example format):
- Emission spectrum wavelengths (nm): 410, 434, 486, 656
- Absorption spectrum wavelengths (nm): 410, 434, 486, 656
Note: These are examples from the hydrogen atom’s visible spectrum (Balmer series). The actual values depend on the specific atom and energy level transitions involved.
Explanation (Approx. 300 words):
Atoms have electrons that exist in discrete energy levels or orbitals. When an atom absorbs energy, an electron can become “excited,” meaning it moves from a lower energy level to a higher one. This is called absorption, and the energy absorbed corresponds to a specific wavelength of light that is removed from a continuous spectrum—this is why absorption spectra appear as dark lines against a colored background.
Conversely, when the excited electron falls back down to a lower energy level, it releases energy in the form of light at a specific wavelength. This emitted light forms the emission spectrum, which appears as bright lines against a dark background.
The wavelengths that appear in an atom’s emission spectrum correspond to the energy differences between two energy levels. Similarly, the absorption spectrum shows the same wavelengths, because they represent the exact amount of energy needed to excite an electron from a lower to a higher energy state.
Therefore, the emission and absorption spectra of an atom consist of the same wavelengths, but they appear in opposite ways (bright lines for emission, dark lines for absorption).
For example, in a hydrogen atom, visible emissions occur when electrons fall to the n=2 level from higher levels (Balmer series). These transitions emit visible light at specific wavelengths like 656 nm (red), 486 nm (blue-green), 434 nm (violet), and 410 nm (violet).
In absorption, the atom absorbs photons of those exact wavelengths to raise electrons from the n=2 level to higher energy levels (n=3, n=4, etc.).
Thus, the absorption spectrum is essentially the inverse of the emission spectrum, but both involve the same set of wavelengths.