What is the reactive nature of aldehydes compared to ketones based on steric hindrance?

The reactivity of aldehydes compared to ketones is significantly influenced by steric hindrance. Aldehydes, which have one hydrogen atom attached to the carbonyl carbon, generally experience less steric hindrance. This structure allows for more effective interaction with nucleophiles, making aldehydes typically more reactive than ketones.

In contrast, ketones have two alkyl groups attached to the carbonyl carbon, which introduces greater steric bulk. This increased steric hindrance makes it more challenging for nucleophiles to approach and react with the carbonyl carbon in ketones. Therefore, they are generally less reactive in nucleophilic addition reactions compared to aldehydes.

Thus, the correct understanding is that ketones are less reactive due to the steric hindrance introduced by their two larger substituents, which inhibits nucleophilic attack at the carbonyl carbon.