Emission Spectra

Introduction

• Emission spectra are patterns of light emitted by atoms when their electrons transition from higher energy levels to lower ones.
• These spectra provide valuable information about an element's atomic structure and are used for identification.

Energy Transitions and Photon Emission

• When an electron in an atom is in an excited state, it can return to a lower energy level.
• During this transition, the electron loses energy, which is released as a photon (a packet of light).
• The energy of the emitted photon is equal to the difference in energy levels the electron moves between.

Calculating Photon Energy

• The energy of a photon (E) can be calculated using the formula:
  • E = hν
• Where:
  • E is the energy of the photon.
  • h is Planck's constant.
  • ν is the frequency of the emitted light.

Specific Energy Transitions

• Each electron transition within an atom corresponds to a specific change in energy levels.
• Therefore, each transition produces a photon with a unique energy, frequency, and colour.

Line Emission Spectra

• Line emission spectra consist of discrete lines of specific colours representing different photon energies.
• These spectra are not continuous, as only light of specific frequencies is produced.
• Line spectra are characteristic of individual elements.

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Emission Spectra

Elemental Identification

• Different elements have distinct energy levels for their electrons, leading to unique line emission spectra.
• By analysing the line spectra of an unknown substance, scientists can identify the elements present.

Comparison with Continuous Spectra

• Continuous spectra, in contrast, are produced by electrons shared between many atoms, resulting in a broad range of possible frequencies.
• Continuous spectra do not exhibit distinct lines and are observed in materials with a continuous energy distribution.

Summary

• Emission spectra are patterns of light emitted when electrons in atoms transition from higher to lower energy levels.
• Each transition corresponds to a specific photon energy and results in line emission spectra.
• Line spectra are used to identify elements based on their unique patterns of spectral lines.
• Continuous spectra are observed in materials with a continuous energy distribution.