Name this molecule: CH2 CH CH2 CH2 CH3.

Study for the IGCSE Edexcel Chemistry Test. Access flashcards and multiple choice questions with hints and explanations. Get ready for your exam!

Multiple Choice

Name this molecule: CH2 CH CH2 CH2 CH3.

Explanation:
This question tests naming alkenes using the longest carbon chain that contains the C=C and the position of that double bond. Look at the structure CH2=CH-CH2-CH2-CH3: there are five carbon atoms in the main chain, so the base name is pent- (five carbons). The molecule has a C=C bond, so we use the -ene ending. The double bond starts at the first carbon when counted from either end, giving the locant 1. Put together, the name is pent-1-ene. If you tried pent-2-ene, that would mean the double bond is between carbons 2 and 3, which isn’t the case here. Hex-1-ene would mean six carbons, which isn’t correct for this structure.

This question tests naming alkenes using the longest carbon chain that contains the C=C and the position of that double bond. Look at the structure CH2=CH-CH2-CH2-CH3: there are five carbon atoms in the main chain, so the base name is pent- (five carbons). The molecule has a C=C bond, so we use the -ene ending. The double bond starts at the first carbon when counted from either end, giving the locant 1. Put together, the name is pent-1-ene. If you tried pent-2-ene, that would mean the double bond is between carbons 2 and 3, which isn’t the case here. Hex-1-ene would mean six carbons, which isn’t correct for this structure.

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