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CH1012
MULTI-ELECTRON
ATOMS
• MOs are only formed when the AOs have
the correct orientation and similar energies.
the correct orientation and similar energies.
• This means that in atoms with more than 2 electrons
the AOs that combine must have similar quantum numbers.
1s will combine with 1s
not with 2s.
2px will combine with
2px not with 2pz
• 2 x s orbitals combine to give a MO with s
symmetry. eg. 2s + 2s ® s2s + s*2s
symmetry. eg. 2s + 2s ® s2s + s*2s
• 2 x px orbitals give a s symmetry MO
• 2 x pz orbitals combine to give a p MO
2 x py orbitals combine to give a p MO
2 x py orbitals combine to give a p MO
