Atomic absorption spectra

1. Definition and Key Concepts

• An atomic absorption spectrum is a continuous spectrum with missing frequencies (dark lines).
• These dark lines occur when specific wavelengths of light are absorbed by atoms in a cool gas.
• Electrons in the gas absorb energy from the light and move to a higher (excited) energy state.
• The energy absorbed is equal to the energy difference between electron energy levels.

2. Characteristics of Atomic Absorption Spectra

• The missing wavelengths correspond to specific elements in the gas.
• Each element has a unique absorption spectrum, acting as a "fingerprint".
• Absorption lines appear at the same positions as emission lines for the same element.
• The higher the frequency of light absorbed, the higher the energy level of electrons.

3. Applications of Atomic Absorption Spectra

• Identifying Elements in Stars:
  • Astronomers use absorption spectra to determine which elements are present in stars and galaxies.
• Chemical Analysis:
  • Used in flame tests to identify metals.
• Medical and Industrial Uses:
  • Analysing blood samples or detecting metal contamination in water.

4. Key Takeaways

• Absorption spectra are unique for each element.
• Dark lines in a spectrum indicate which wavelengths have been absorbed.
• Combining an element's emission and absorption spectra results in a continuous spectrum.