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Electron Sharing and bonding

  1. Nov 23, 2015 #1
    There's a rule bout unlike charges attract and like charges repel one another. How is it that in chemical bonding like in covalent bonding electrons form a bond or there is attraction from one unto the other. Isn't that ironic?
     
  2. jcsd
  3. Nov 23, 2015 #2

    jfizzix

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    Well, to take the simplest example of the bond in a hydrogen molecule, you have two positively charged nuclei, and two electrons. Each electron is attracted to both nuclei, but repelled by the other electron. Chemical bonds are then a sort of compromise; it's a local equilibrium where it would take more energy to smoosh them closer closer together or pull them further apart.

    That two electrons can be in the vicinity of positively charged nuclei is not without precedent.
    After all, Helium atoms have two electrons orbiting each of them and are stable, even though the electrons repel each other.
     
  4. Nov 23, 2015 #3
    But isn't Hydrogen atom electrically neutral? One +p and -e, what is then the attraction between one over the other? Is it not gravity or something?
     
    Last edited: Nov 23, 2015
  5. Nov 23, 2015 #4

    DrClaude

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    Forget about gravity. What you have, at long range, is the interaction of the instantaneous dipole. As the two atoms get closer, you will have the electron of one atom having a non-negligible overlap with the nucleus of the other atom.
     
  6. Nov 23, 2015 #5
    That's is more real I agree. thanks.
     
  7. Nov 23, 2015 #6

    DrDu

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    There is no attraction between the electrons and mutual repulsion of the electrons is rather an obstacle to bond formation. As others pointed out already, this repulsion is partially made off by the attraction of the nuclei, but this wouldn't explain bonding.
    The real reason behind bond formation is a quantum mechanical one: According to Heisenberg's uncertainty relation, the average momentum of an electron will be the lower, the more space it can occupy. Lower momentum also means lower kinetic energy. In a molecule, an electron has the chance to be found on either of two atoms instead of only one before bond formation. Hence it can occupy more space and it's kinetic energy gets lower.
     
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