Yes, according to the wave-particle duality of light, a single atom can emit light as both a wave and a particle. In quantum mechanics, particles such as atoms can exhibit wave-like behavior under certain circumstances. When an atom undergoes a transition between energy levels, it can emit or absorb photons, which are discrete packets of electromagnetic radiation.
When an atom emits light, it can be described as emitting photons, which are particle-like entities. Each photon carries a specific amount of energy and momentum and can interact with matter as a particle. This particle-like behavior is evident when we observe individual photon interactions, such as in the photoelectric effect.
However, the behavior of light can also be described using wave concepts. Light waves exhibit properties like interference, diffraction, and polarization. These wave-like properties are observed when light undergoes phenomena like interference patterns in the double-slit experiment or the diffraction of light through a narrow slit.
Therefore, when an atom emits light, it releases photons as discrete particles, but these photons collectively form a wave that exhibits wave-like properties. The wave-particle duality allows us to understand and explain the behavior of light in different experimental scenarios.