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Chemistry LibreTexts

Molecular Orbitals

  • Page ID
    31929
  • The following diagrams illustrate the combination of molecular orbitals in 'fragments' to produce molecular orbitals in common molecules. The purpose of this page is to show how orbitals combine (overlap) to produce sigma and pi bonds. The orbitals were all calculated using semiempirical calculations, so the results shown should not be considered highly accurate.

    s + s = sigma (σ)

    H Atom s orbital + H Atom s orbital = H2 Molecular Orbital
    s atomic orbital s atomic orbital sigma (σ) bond

    s + p = sigma (&sigma)

    H Atom s orbital + CH3 with p orbital = Methane molecular orbitals
    s atomic orbital p-like orbital sigma (σ) bond

    p + p = sigma (σ)

    CH3 with p orbital + CH3 with p orbital = Ethane molecular orbitals
    p-like orbital p-like orbital sigma (σ) bond

    sigma vs. pi bonds

    Ethane molecular orbitals Ethene molecular orbitals
    sigma bond (σ) pi bond (π)