Question

I understood this at one point and now I'm confused again! :(
What's the difference between 2,2-dimethyl and 2-ethyl? It's hard to find proper drawings online...
For example, for naming CH3CH2C(CH3)2CH2NH2,
Why wouldn't it be 2-ethyl-1-butanamine rather than 2,2-dimethyl-1-butanamine?

Thanks so much in advance! This unit is really difficult for me :(

Answer 1

2,2 dimethyl means two CH3 branches attached to the second carbon of the parent chain.

2-ethyl means the -CH2CH3 chain attached to the second carbon of the parent chain. the parent chain is the longest chain.

the longest chain in the formula you gave consisted of 4 carbons i.e. from the Carbon attached to the NH2 to the CH3 at the leftmost. The (CH3)2 means that two CH3 branches attached to C i.e. C(CH3)2 which is on Carbon 2. so, two CH3 is dimethyl, on carbon 2 is 2-dimethyl.....amine

2-ethyl-1-butanamine means that the -CH2CH3 is attached to carbon number 2 (when counting from the NH2),of the parent chain consisting of 4 carbons. so the only way to do that is to remove the (CH3)2 branches and plug in the CH2CH3 branch.