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chemistry unit 4 aqa asymmetric carbon atoms?

http://filestore.aqa.org.uk/subjects/AQA-CHEM4-QP-JAN13.PDF

question 4a)i
i don't get it

i get what it means [i think?] but getting the answer wrong
Do you know what asymetric means? It means that every single carbon atom has four different bonds which are chiral. Chiral means that their structure is identical, but mirror-inverted. Here is an example:

http://upload.wikimedia.org/wikipedia/commons/thumb/e/e8/Chirality_with_hands.svg/765px-Chirality_with_hands.svg.png

As far as I understand the task you should draw such chiral molecules.
Reply 2
Avatar for zilly1
zilly1
Original post by pureandmodest
http://filestore.aqa.org.uk/subjects/AQA-CHEM4-QP-JAN13.PDF

question 4a)i
i don't get it

i get what it means [i think?] but getting the answer wrong



An asymmetric carbon is attached to 4 different atoms or groups.

Example, The asymmetric carbon atom is the one attached to two carbon atoms, an oxygen atom, and a hydrogen atom. One may initially be inclined to think this atom is not asymmetrical because it is attached to two carbon atoms, but because those two carbon atoms are not attached to exactly the same things, there are two different groups of atoms that the carbon atom in question is attached to, therefore making it an asymmetric carbon atom

Reply 3
Avatar for zilly1
zilly1
Original post by pureandmodest
http://filestore.aqa.org.uk/subjects/AQA-CHEM4-QP-JAN13.PDF

question 4a)i
i don't get it

i get what it means [i think?] but getting the answer wrong



How many can you find for the question?
Original post by zilly1
How many can you find for the question?


it's either 3 or 4
i'm not sure about the threonine. the one directly attached to the carbonyl c=o bond is asymmetrical, right?
but i'm not sure about the one above that. the one with the h-c-oh bond?
Reply 5
Avatar for zilly1
zilly1
Original post by pureandmodest
it's either 3 or 4
i'm not sure about the threonine. the one directly attached to the carbonyl c=o bond is asymmetrical, right?
but i'm not sure about the one above that. the one with the h-c-oh bond?



It's 4, the h-c-oh is because although attached to 2 carbons they are in different environments.
Original post by zilly1
It's 4, the h-c-oh is because although attached to 2 carbons they are in different environments.


ohh okay!
thankyou so much, i was so confused about this but it makes sense now :smile:
Reply 7
Avatar for zilly1
zilly1
Original post by pureandmodest
ohh okay!
thankyou so much, i was so confused about this but it makes sense now :smile:


Pleasure, good luck in your exams (I got my degree in applied chemistry in 2005).

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