Energy levels in atoms

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Thermal Radiation

  • All objects with a temperature above absolute zero emits thermal radiation

Why do objects emit this radiation?

  • All charged particles emit radiation when they accelerate
  • If an object has a temperature above absolute zero, then its electrons and protons will vibrate and emit radiation
  • Absolute zero is the temperature (-273oC, 0k) at which particles theoretically lose all their energy and stop vibrating.
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How do line spectra originate from hot gases?

  • A hot gas emits thermal radation at a set of discrete wavelengths. This corresponds to the emission of photons at a set of fixed energies.
  • In Bohr's model of the atom, electrons are present in several different sized orbits. Electrons in the outer orbits have a higher energy than electrons in the lower orbits.
  • When an electron drops down from a higher energy level towards the ground state the difference in energy is released as a photon
  • Electron energy levels are usually represented using horizontal lines. The ground state is at the bottom and the higher levels are arranged above.
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