CHEM261 Lecture Notes - Sigma Bond, Antibonding Molecular Orbital, Linear Combination
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CHEM261 Full Course Notes
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As two hydrogen atoms come together, molecular hydrogen (h2) is formed. 2 x h (single h atom with 1 electron) Energy diagram of two hydrogen atoms interacting to form a bond: 1 is the average h-h bond distance e. g. h2. Combination of atomic orbitals of s- character gives molecular orbital called sigma molecular orbital ( ) Mixing of atomic orbitals (with the wrong geometry for bonding) to form hybrid orbitals with the correct geometry for bonding. Will only happen for bonding sp3 hybridization. Angle between two h atoms in methane: 109 , close to that with other elements. No free rotation around double bonds because the p orbitals have to line up. Overlap of atomic orbitals with s component gives sigma molecular orbital (bond) H ethylene = ethene sigma + pi = double bond sp2+sp2 p+p. Angle between two atoms: 180o e. g. acetylene/ethyne. 1s y sigma (s of h and sp of c)
