[CasualSoul]

please see attatched

Thank you in advance


Edit - see second drawing...tried to correct it based on comments given ..the oxygen still looks a bit dodgey though

[cosmobear92]

I could be wrong, but shouldn't the methyl groups be attached to the next carbon, as in the second carbon from the left? Soz, it's been like a year since I did chem.
And your oxygens are wrong as well.

[illusionz]

Your carbon backbone is correct but your oxygens are completely wrong. How many bonds does each carbon and each oxygen need?

[Jack_Smith]

(Original post by cosmobear92)
I could be wrong, but shouldn't the methyl groups be attached to the next carbon, as in the second carbon from the left? Soz, it's been like a year since I did chem.

thats what i thought, shouldnt it be placed from the shortest end? :/

[KyraBloke]

(Original post by cosmobear92)
I could be wrong, but shouldn't the methyl groups be attached to the next carbon, as in the second carbon from the left? Soz, it's been like a year since I did chem.

Carbon 1 is the COOH carbon, so he's right there xd


However, one of your oxygens has 3 bonds :P

You need to have both of the oxygens attached to the carbon - not one Oyxgen attached to another.

[cosmobear92]

(Original post by KyraBloke)
Carbon 1 is the COOH carbon, so he's right there xd


However, one of your oxygens has 3 bonds :P

You need to have both of the oxygens attached to the carbon - not one Oyxgen attached to another.

Aah no, yeah you're right. It's the oxygens that are drawn wrong, the -COOH group is meant to be drawn like this:

[CasualSoul]

ooo right! right so does oxygen always have to have 4 bonds like carbon?

Also I'm gonna try and correct it..please tell me if its right

[cosmobear92]

Carbon has four bonds, oxygen has two bonds

[illusionz]

(Original post by CasualSoul)
ooo right! right so does oxygen always have to have 4 bonds like carbon?

No. A simplified rule for oxygen:

1 bond - negatively charged
2 bonds = neutral
3 bonds = positively charged

If you're not expecting it to have a charge and it doesn't have 2 bonds, you've done something wrong.

[CasualSoul]

Also, in the second drawing above I've placed the two methly groups on the second carbon counting from the RIGHT

If I decided to place them on the second carbon counting from the LEFT would it be right

[KyraBloke]

(Original post by CasualSoul)
Also, in the second drawing above I've placed the two methly groups on the second carbon counting from the RIGHT

If I decided to place them on the second carbon counting from the LEFT would it be right

It'd be wrong if you were to do this. There a certain rules when naming carbon structures. I struggle remembering them (in A2 there's a few more to remember), but i know in this instance, the COOH carbon is carbon 1.

Btw, an easy way to remember how many bonds atoms can form is this.

1 2 3 4
H O N C

[cuckoo99]

if you are still not sure and if you do biology aswell check out the structual formula for an amino acid as there is a carboxylic acid attached there too

[CasualSoul]

right, I think I sorta know what I'm doing now..just need to practice a couple of these and ensure my oxygens and carbons have the correct number of bonds.

Thanks people.

[lukas1051]

You need to learn the functional groups, once you identify which ones should be present the rest is easy. Your second drawing is correct.

With any carboxylic acid, so you should immediately draw -COOH (C with a double bond to O a single bond to OH and a single bond to a carbon chain - this is a standard, common functional group). The next piece of information is the number of carbons in the chain given by but- and then the methyl chains are added last, counting from the carbon attached to the functional group - in this case the C on -COOH is number one. In the first drawing, assuming your carboxylic acid group was correct, it would still be wrong because you have not counted from the correct carbon.

You should never have to worry about the number of bonds as long as you get your basic functional groups correct because it all falls into place. Just be aware of C=C double bonds, and obviously remember that carbon has four bonds.

[CasualSoul]

yes lukas!

just added all that to my notes- great summary

[lukas1051]

(Original post by CasualSoul)
yes lukas!

just added all that to my notes- great summary

No problem. If you need chemistry notes/revision material, this website is probably the best one of the internet if you don't already know about it: http://www.knockhardy.org.uk/ppoints.htm