Hi everyone. Could anyone please explain to me why the Coordination Number (number of nearest neighbors - also called bulk coordination number I think) influences the size of an atom. So if a particular atom has a CN of 12 it will occupy more volume than the same atom with a CN of 8 or 4. Is this something to do with the quantum mechanical orbital bonding? Could it possibly be something how the electron cloud 'stretches out', so to speak, to 'reach' the neighboring atoms? I have searched and I can't find anything which explains this. Thanks in advance.