Is the there not repulsion between the individual electrons within the bonding pairs ? Why does the "bonding pair " have an overall repulsive effect on the other lone and bonding pairs ?


There is repulsion between the individual electrons of a bonding pair (and within a lone pair, for that matter). The reason that the electrons can be found in that "pair" nonetheless is that those "pairs" are actually orbitals - allowed "spaces" for electrons. Of these orbitals, there are many more than there are electrons in a molecule: they can thus be classified as occupied and unoccupied. They differ in energy: the "closer" an orbital is to a nucleus, for instance, the lower the energy of the electrons occupying it. Often, the electrons are lower in energy when sharing an orbital than when not sharing it - because in case of the latter, one of the electrons ends up in a higher orbital (think Aufbau principle). One might also say that the electron-nucleus attraction overcomes the electron-electron repulsion of the electrons within a pair.

The natural question to ask next is: why do we not have more than 2 electrons per orbital? The answer is that you cannot have 2 electrons with the same spin (a fundamental relativistic property of an electron) in one orbital (There are reasons for this, but elaborating them goes too far at this point). Electrons have either +1/2 or -1/2 spin - thus you get one of each within a VSEPR pair.

There is repulsion between electron pairs, simply as a result of the identical charges of the electrons.

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