Electron transition

An electron transition is the process by which an electron in an atom or molecule changes its energy level. This means it moves from one orbital (a region of probability where an electron is most likely found) to another, either closer to or further away from the nucleus.

Energy Levels
  • Imagine electrons orbiting the nucleus of an atom like planets around the sun.
  • Each electron occupies a specific energy level, similar to how planets exist in distinct orbits.
  • These levels are quantized, meaning they have specific allowed values and electrons cannot freely exist between them.
  • Electrons can absorb energy from various sources like light, heat, or electrical fields.
  • This energy “boosts” them to a higher energy level, similar to a planet receiving a push and moving further from the sun. This process is called excitation.
  • Excited electrons are unstable and want to return to their lower energy (ground state) like a planet settling back into its original orbit.
  • When they do, they release the excess energy in the form of light, heat, or other forms of radiation.
Types of Transitions
  • Absorption: An electron absorbs energy and moves to a higher level.
  • Emission: The electron releases energy and moves to a lower level.
  • Non-radiative transition: Electron loses energy without emitting light, often through collisions with other atoms.
About shells & orbitals
  • Think of shells as regions around the nucleus where electrons are most likely to be found. These regions are like “zones” or “areas” within the atom, organized according to their energy levels.
    • Shells are labelled using letters (K, L, M, N, etc.) starting from the nucleus outwards. Each shell has a specific energy, with the K shell being closest to the nucleus and having the lowest energy, followed by L, M, and so on.
    • Imagine them as concentric circles around the nucleus, with outer shells being like bigger “orbits” further away.
  • Within each shell, electrons occupy specific orbitals, which are subregions of probability where an electron is most likely to be found. These orbitals are like specific “paths” or “locations” within each shell.
    • While the shell gives a general region, the orbital pinpoints the specific area where the electron spends most of its time.
    • Each shell can hold a specific number of electrons depending on its shape and energy level.
Connecting Shells and Orbitals to Energy Levels
  • Each shell and orbital has a unique energy level. Electrons in lower shells (closer to the nucleus) and orbitals have lower energy levels than those in higher shells and orbitals. This is because they experience a stronger attraction from the positively charged nucleus, holding them closer and requiring more energy to escape.
  • Electron transitions typically happen between orbitals in different shells or within the same shell but with different energy levels. When an electron absorbs energy, it jumps to a higher-energy orbital (excitation). When it releases energy, it moves to a lower-energy orbital (de-excitation).
  • Imagine a carbon atom with six electrons. Two electrons are in the lowest energy K shell (1s orbital). The remaining four electrons occupy the L shell, two in the lower-energy 2s orbital and two in the slightly higher-energy 2p orbitals.
  • When a carbon atom absorbs light, one of the electrons in the 2s orbital might get excited and jump to an empty 2p orbital, moving to a higher energy level within the same shell.
Key Points
  • Shells and orbitals are ways to visualize the location and energy levels of electrons around the nucleus.
  • Electrons occupy specific orbitals within shells, with each shell having a unique energy level.
  • Electron transitions involve movement between orbitals, driven by absorption or release of energy.