What differentiates an atom's ground state from an excited state?

An atom's ground state is characterized as its lowest energy configuration, where electrons are in their most stable arrangement. In contrast, an excited state occurs when an atom absorbs energy, causing one or more of its electrons to move to a higher energy level. This transition to a higher energy level represents a temporary state because the excited electrons will eventually return to the ground state, releasing energy in the process.

Understanding that the excited state signifies an atom's electrons occupying an energy level above their normal configuration is key to grasping atomic behavior. This differentiation between ground and excited states is crucial in various applications, such as spectroscopy and understanding chemical reactions, as it illustrates how energy absorption and emission can alter atomic structures.