Excited State

Definition

An excited state is a condition of an atom or molecule in which one or more electrons have absorbed energy and moved to a higher energy level than their ground state. This temporary state occurs when energy is supplied to the atom, often through absorption of light, leading to various phenomena such as spontaneous emission as the electrons eventually return to their ground state, releasing energy in the form of photons.

5 Must Know Facts For Your Next Test

1. An excited state is typically short-lived and will return to the ground state quickly, often within nanoseconds.
2. The energy difference between the ground state and excited state corresponds to the wavelength of light absorbed, determining the specific colors of light that an atom can absorb.
3. When an electron falls back from the excited state to the ground state, it releases energy in the form of a photon, which is responsible for phenomena like fluorescence.
4. Different atoms have unique energy levels, which results in each atom having a distinct pattern of absorption and emission lines in their spectra.
5. Excited states can lead to various applications, such as lasers, where controlled transitions between energy states are utilized to produce coherent light.

Review Questions

• How does an atom transition from its ground state to an excited state, and what role does energy play in this process?
  • An atom transitions from its ground state to an excited state when it absorbs energy, usually in the form of photons from light. This energy causes one or more electrons to move to higher energy levels. The amount of energy absorbed must match the energy difference between the ground state and the excited state's electron configuration. Once excited, the atom holds this state temporarily before returning to its ground state.
• Discuss how spontaneous emission relates to the concept of excited states and the behavior of atoms after they transition to these states.
  • Spontaneous emission occurs when an electron in an excited state returns to a lower energy level or ground state without external influence. As it does so, it releases energy in the form of a photon. This process illustrates how excited states are not stable; they exist only for a brief moment before spontaneously emitting light. The characteristics of this emitted light depend on the specific energies involved in the transition.
• Evaluate the significance of excited states in laser technology, considering how they influence the production of coherent light.
  • Excited states play a crucial role in laser technology by enabling controlled transitions that lead to stimulated emission. When a population of atoms is excited to a higher energy level through external pumping, they can be stimulated by incoming photons to emit additional coherent photons as they return to their ground states. This amplification process is fundamental to laser operation, resulting in highly focused and coherent beams of light that have numerous applications in fields ranging from medicine to telecommunications.

Related terms

Ground State: The lowest energy state of an atom or molecule, where electrons occupy the closest possible orbitals to the nucleus.

Photon: A quantum of electromagnetic radiation, which can be emitted when an electron transitions from an excited state back to a lower energy level.

Absorption Spectrum: A spectrum showing dark lines or bands that indicate wavelengths absorbed by electrons transitioning to higher energy levels in an atom.