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2.7A: MO Theory: Orbital Interactions

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    Factors affect the strength of orbital interaction:


    1. Jean, Yvesand and Volatron, François. An Introduction to Molecular Orbitals. Oxford University Press. 11.03. 2005
    2. McBride, J. M. “MO Interactions (HOMO/LUMO)”. 2001. 07 Oct 2010. <>
    3. Housecroft, Catherine and Sharpe, Alan. Inorganic chemistry. 3rd edition. Prentice Hall. December 9, 2007

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    1, How do molecules orbitals form?

    The formation of molecular orbitals is from the overlap of atomic orbitals; or more specific, from the wave interaction of atomic orbitals.

    2, What are the factors that affect the orbital interaction?

    There are some significant factors that affect the strength of orbital interaction

    - Symmetry of the molecule orbital

    - The difference between orbitals’ energies

    - The orbitals' sizes

    - The distance between orbitals

    3, What are HOMO and LUMO? How do they interact in the molecule orbitals?

    The highest energy occupied molecular orbital is called HOMO

    The lowest energy unoccupied molecular orbital is called LUMO

    These orbitals are a pair and they lie very close together in energy of two molecules. Therefore, the interaction between them is very strong.

    4, What are the two types of electron waves interaction?

    In-phase and out of phase interactions

    5, How do the intensity of negative charge of electrons change in each types of of electron waves interaction?

    The intensity of negative charge of electrons increases in the in-phase interaction and decreases in the out-of-phase interaction.