Can eclipsed and staggered conformations of ethane be isolated? Give reasons.
No, because the difference of energy between these two conformations is very small, so even at room temperature these two interconvert rapidly and hence cannot be isolated.
What kind of structural isomerism is shown by alkenes ?
Alkenes show two types of structural isomerism:
(i) Chain isomerism: It is caused by different arrangements of carbons in the chain. For example.
(ii) Position isomerism: It is caused due to the different positions of a double bond in the alkene. For example 1-butene and 2-butene.
Calculate the number of sigma (σ) and pi bonds in the following structures:
What are alkenes ?
What are the necessary and sufficient conditions for a compound to exhibit geometrical isomerism ?
Conditions for geometrical isomerism: There are two necessary conditions for a compound to possess geometrical isomerism:
(i) It must contain a carbon-carbon double bond in the molecule.
(ii) Two unlike atoms or groups must be linked to each doubly bonded carbon atoms.
Geometrical isomerism among alkenes does not occur when the doubly bonded carbon carry identical atoms or groups. For example, AAC = CAB does not exhibit geometrical isomerism.