Which of the following best explains the presence of discrete lines in atomic emission spectra?

• A. Electrons in atoms transition between specific energy levels, emitting photons of distinct energies.
• B. The nucleus of the atom vibrates at certain frequencies, producing discrete spectral lines.
• C. Atoms emit a continuous range of energies as electrons move randomly within the atom.
• D. Electrons are ejected from the atom, causing the emission of a broad spectrum of light.

Answer: (A)

Verified step by step guidance

1. Understand that atomic emission spectra consist of discrete lines, which means the emitted light has specific wavelengths rather than a continuous range.
2. Recall that electrons in an atom occupy quantized energy levels, meaning they can only exist at certain fixed energies.
3. When an electron transitions from a higher energy level to a lower energy level, it emits a photon whose energy corresponds exactly to the difference between these two levels.
4. The energy of the emitted photon determines the wavelength of the light, given by the equation \(E = \frac{hc}{\lambda}\), where \(E\) is energy, \(h\) is Planck's constant, \(c\) is the speed of light, and \(\lambda\) is the wavelength.
5. Because the energy levels are discrete, the photons emitted have specific energies, resulting in discrete lines in the emission spectrum.