3-methylpent-2-ene isomer

Yes, it does. Of the two carbons on the double bond, one has hydrogen and CH3, the other has CH3 and C2H5. Each has two different groups, so there are cis-trans isomers.

Hey had a feeling they had E/Z isomers, just needed some reassurance. Sorry to bother again, but could you please push me in the right direction with this one, too?

3,4-dimethylhex-3-ene.

I draw the double bonds with the methyl groups but I'm unsure where to place the hydrogen's? Do I have to try and balance them on each side of the double bond?

Anyway, when I draw the skeletal structure I get two CH3 groups and two CH2C groups. Therefore, will they only be cis-trans isomers?

Thanks

You're correct, each carbon in the double bond has a CH3 and C2H5 group attached. Given that each has two different groups, they are cis-trans

I'm not sure what you mean by balancing hydrogens. They are balanced on either side of the double-bond, but only because this particular molecule happens to be symmetrical. If it was 'hept' instead of 'hex', it wouldn't be symmetrical.

Thanks for the help! What I mean by balancing hydrogen's is, for example:

2-ethylpent-1-ene. When I draw the structural formula two carbons are completely unsaturated. Would this be correct? Or would I have to share the hydrogen's so as many carbons can have at least 1 hydrogen; or do I just give the first carbon the maximum amount of hydrogen's then move to the next carbon?

May be a silly question and sorry if it doesn't make sense. Only into my second week of AS!

When finding the structure of a hydrocarbon, start with the main chain. In this case, it's 'pent', so there are 5 carbons in the longest chain. Choosing to list these 5 carbons 1-5 from one end to the other, we can then add the functional groups. There is a double bond in position 1 - this means linking carbon 1 and 2 is a double bond. Secondly, there is an ethyl group on the second. We now know that the second is bonded to carbon 1 (by a double bond), carbon 3 (and the rest of the main-chain) and the ethyl group. This makes four bonds on carbon two, so it cannot have any more bonds, so is not bonded to any hydrogen atoms. All the other carbon atoms still have bonds 'left over', so they are all bonded to hydrogen atoms.

Hope that wasn't too confusing.