Why energy is released when an electron is added to a neutral atom?

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If the electron statistical distribution around the atomic kernel had been perfectly spherically symmetric, and if the electron occurance distribution had not mutually overlapped, than by the Gauss law of electrostatics, the net force between a neutral atom and an electron would have been zero.

But as neither of above conditions is true, a kernel charge is not fully screened off by electrons, acting as having a residual, "effective charge", what allows releasing energy by bounding an extra electron. See Slater rules.

An extra electron puts among other electrons some extra stress=mutual repulsion, what somewhat decreases this released energy.

As effective kernel charge and electron mutual repulsion ( classical and Pauli ones ) are 2 major factors affecting energies of electron orbitals in multi-electron atoms.

When the former factor is stronger, energy is released by an extra electron bounding, like for fluorine. And vice versa, like for helium.

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Wolgwang
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Wolgwang

Updated on January 31, 2023

Comments

  • Wolgwang
    Wolgwang 9 months

    Question :

    Why energy is released when an electron is added to a neutral atom?

    I read somewhere

    “When electrons are added to an atom, the increased negative charge puts stress on the electrons already there, causing energy to be released.”

    I didn't understand What is stress and how energy is released due to stress?

    • AChem
      AChem about 3 years
      Please do not personify atoms and sub-atomic particles. Electrons and atoms are not human beings who have to vent their energy in order to de-stress. Whoever wrote it just ignore this statement because the writer does not know what he/she is writing. Sub-atomic particles have a world of their own which is very different from what we know and understand. There is no such thing as stress or congestion of having too many electrons.
    • Wolgwang
      Wolgwang about 3 years
      @M. Farooq Ok I ignore that statement.
    • AChem
      AChem about 3 years
      Search about electron affinities "electron affinities can be negative (energy is released when an electron is added), positive (energy must be added to the system to produce an anion), or zero (the process is energetically neutral)". See google.com/…
    • AChem
      AChem about 3 years
      The point is that energy is not always released.
    • Poutnik
      Poutnik about 3 years
      @M. Farooq Note that stress has multiple meanings and only some of them are related to feelings as a high discomfort. Some others are objective, like the one used in mechanical engineering as a tension. It may be stretched being applied to quantum systems, but has nothing to do with human emotions.
    • Wolgwang
      Wolgwang about 3 years
      @M. Farooq I know that electron affinities can be negative. But my question is “Why sometime energy is released?”
    • Poutnik
      Poutnik about 3 years
      But the stress=repulsion is not reason of energy release.
    • Wolgwang
      Wolgwang about 3 years
      @Poutnik Yes. That's why I am asking the reason.
  • Wolgwang
    Wolgwang about 3 years
    Can you define energy? I thought heat energy changes.
  • Poutnik
    Poutnik about 3 years
    Who am I to define energy, if it is already defined and definition available on many places ? :-)
  • Wolgwang
    Wolgwang about 3 years
    In my physics textbook, it is defined as "The capacity to do work".
  • Poutnik
    Poutnik about 3 years
    See e.g.Wikipedia
  • Wolgwang
    Wolgwang about 3 years
    Ok Got it. Thanks
  • Admin
    Admin about 3 years
    No element releases energy by losing an electron.
  • Maurice
    Maurice about 3 years
    @ Yuvraj. Sorry ! Your long comment is nearly unreadable, because it has no punctuation sign. No points, no commas !