Which one of the following organic compounds have the least carbon-carbon bond length?
Correct answer: C. Ethyne
- A. Ethene
- B. Ethane
- C. Ethyne
- D. Methane
Explanation
The bond length for a given pair of elements is a function of number and types of orbital overlaps. Single bonds, with their end-to-end overlap called sigma bonds are the longest (and also the weakest). A double bond consists of a sigma bond and a pi bond, the side to side overlap of p-orbitals. This moves the nuclei closer together and decreases the bond length (and increases the bond energy). A triple bond consists of two pi bonds and a sigma bond. The additional pi bond isn't any shorter than the first pi bond, but together the two pi bonds provide additional attraction and shorten the sigma bond allowing the triple bond to be the shortest (and strongest).C−C .......... 154 pmC=C .......... 134 pmC≡C .......... 121 pm
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About Alkynes
Alkynes are unsaturated hydrocarbons containing a carbon-carbon triple bond, with sp-hybridised carbon atoms and a linear arrangement around the bond. The content includes nomenclature, preparation, acidity of terminal alkynes, and addition reactions with hydrogen, halogens, hydrogen halides and water, as well as oxidation.
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