Two methyl radicals approach each other so that the axis joining the two carbon atoms is colinear. Each carbon is tetrahedrally surrounded by three hydrogen atoms and one unpaired electron.
Consider whether a double bond could form between the two carbon atoms under these conditions.
(1) Explain why two carbon atoms that are each sp3-hybridized cannot form a π bond with one another without first changing their hybridization.
(2) Describe how the orientation of the lobes in the sp3 hybrids on each carbon allows free rotation around the C–C σ bond that actually forms between the radicals.
(3) If the two carbons were re-hybridized to sp2, describe how a C=C double bond could form and predict how rotation about the internuclear axis would be affected.