Defining the Excited State
An excited state occurs when an electron within an atom or molecule absorbs energy and moves from its usual lowest energy level (ground state) to a higher energy level. This elevated state is temporary and unstable, meaning the electron will not remain there indefinitely.
How Atoms Reach an Excited State
Atoms can enter an excited state by absorbing energy from various sources, such as heat, light (photons), or electrical discharge. When an electron gains sufficient energy, it "jumps" to an unoccupied orbital further from the nucleus, corresponding to a higher energy shell or subshell.
Light Emission: Returning to Ground State
Because an excited state is unstable, the electron quickly falls back to a lower energy level, eventually returning to its ground state. As it descends, it releases the absorbed energy, often in the form of electromagnetic radiation, such as visible light (e.g., in neon signs or fireworks) or other forms like UV or infrared.
Significance in Science and Technology
Understanding excited states is crucial for fields like spectroscopy, which analyzes the light emitted or absorbed by substances to identify their composition. It's also fundamental to technologies such as lasers (where atoms are purposefully put into excited states to amplify light), LEDs, and fluorescent materials, which all rely on controlled electron transitions.