Final answer:
To say that an atom is excited means that its electrons have been boosted to higher energy levels due to energy absorption, and they can emit light or photons as they return to lower energy levels.
Step-by-step explanation:
To say that an atom is excited is to say that one or more of its electrons have absorbed energy and have been promoted to higher energy levels than their ground state. This process is known as atomic excitation. When an atom absorbs enough energy, its electrons can be boosted into a higher shell or energy level, moving at greater speed and possessing more kinetic and potential energy. Eventually, these excited electrons tend to release some of the absorbed energy by jumping back to their original or lower energy levels, often emitting light or a photon in the process. This is a foundational concept in the study of quantum mechanics and spectroscopy, where the phenomena of absorption, emission, and the energy levels of electrons are crucial.