Rotation about a carbon to carbon double bond is restricted because
Correct answer: C. turning one carbon would break the sideways overlap of the pi bond
- A. the sigma bond is too strong
- B. the atoms are too heavy
- C. turning one carbon would break the sideways overlap of the pi bond
- D. double bonds are ionic
Explanation
The pi bond depends on two parallel p orbitals overlapping sideways, and rotating one carbon by ninety degrees would destroy that overlap, which costs far more energy than is available at room temperature. This rigidity is what makes cis and trans isomerism possible in alkenes. Single sigma bonds rotate freely because their overlap is symmetrical about the axis.
Report an error
The more specific you are, the faster it gets fixed. A source beats an opinion.
Prefer email? support@testustad.com
About Sigma and Pi Bonds
A sigma bond forms by direct end-to-end overlap along the internuclear axis, whereas a pi bond forms by sideways overlap of parallel orbitals. The topic covers single, double and triple bonds, bond composition, restricted rotation and the relation between sigma and pi bonding and orbital hybridisation.
Practise Chemical Bonding
964 free Chemical Bonding MCQs from Chemistry, each with the correct answer and an explanation. Unlimited attempts, no account needed.
Discussion
Stuck on an option, or know a faster way to get there? Ask or explain it here.
No comments yet. Be the first to explain this one.
Exams that ask Chemistry questions like this
Chemistry is on 14 papers prepared for on TestUstad, and all of them draw the same bank, so this question is worth knowing for every one of them.
More Sigma and Pi Bonds questions
The number of sigma and pi bonds in a molecule of ethyne, C2H2, is
A sigma bond is formed by
In the ethene molecule, the carbon to carbon double bond consists of
A coordinate or dative covalent bond differs from an ordinary covalent bond in that
The number of sigma and pi bonds in a molecule of carbon dioxide is
A pi bond is weaker than a sigma bond because