Question 5.3: Hybrid Orbitals in Larger Molecules Propylene, C3H6, a start......
Hybrid Orbitals in Larger Molecules
Propylene, C_3H_6, a starting material used to manufacture polypropylene polymers, has its three carbon atoms connected in a row. Draw the overall shape of the molecule, and tell what kinds of orbitals on each atom overlap to form the C-C and C-H bonds.
STRATEGY
Draw an electron-dot structure of the molecule, use the VSEPR model to predict the geometry around each carbon atom, and predict the hybridization of each carbon atom based on the VSEPR bond angles.
A molecule with the formula C_3H_6 and its carbons connected in a row does not have enough hydrogens to give each carbon four single bonds. Thus, propylene must contain a double bond and have two trigonal planar carbon atoms along with one tetrahedral carbon. Trigonal planar atoms have 120° bond angles and sp² hybridization, while tetrahedral atoms have 109° bond angles and sp³ hybridization. Thus, the C—C single bond is formed by overlap of an sp³ orbital and an sp² orbital, the C=C double bond is formed by overlap of two sp² orbitals and two p orbitals, and each C-H bond is formed by overlap of a hydrogen 1s orbital with the hybrid orbital on the carbon to which it is attached.
