Question 31

[mvenus9292913]

This doesn't exactly pertain to the question being asked, but I was curious because I've seen a question about it before (not through MCAT, but through ACS).

Can an atom other than a carbon atom form a chiral molecule? i.e. can a nitrogen with 4 different groups be considered a chiral molecule?

[admin]

The answer is YES ! However, you won't see that on the MCAT!

Even though you have given the definition that all students know about chiral compounds (bonded to 4 different substituents, perfect for the MCAT), the textbook definition is as follows:

Of or relating to the structural characteristic of a molecule that makes it impossible to superimpose it on its mirror image.

[rm5165104]

Will the MCAT specify "chiral carbon" or will they simply say "chiral center"? If it says "chiral center" should we just assume that they are specifically talking about the chiral carbons and nothing else?

Thank you.

[admin]

They can say either "carbon" or "center" and yes, by default for the MCAT, "center" refers to the central carbon.

Sometimes with the MCAT, you need to "go with the flow." The reason you practice so much is so that you can recognize patterns and be exposed to many posibilities. However, you must be open to the chance that they may use terminology on your test that is just a bit different from what you may have studied in undergrad. Be flexible and you'll be fine.

[admin]

bump

[mohsinalam5969]

A carbon bonded to four different groups is called a chiral carbon or a chirality centre. The chirality centre is indicated by asterisk.
Carbons that can be chirality centres are sp3-hybridised carbons; sp2 and sp-hybridised carbons cannot be chiral carbons because they cannot have four group attached to them.
The most prevalent chirality centers in organic chemistry are carbon atoms, which have four different groups bonded to them.
Any atom which has four different groups bonded to it is a chirality center. The more common of these atoms, with which an organic chemist should be familiar, are Si, N and P (note: a lone pair is included as one of the four different groups) They may be tetrahedral molecules or trigonal pyramidal molecules (where a lone pair is included as one of the four different groups).
I hope now you can easily understand this.

[berrahhh3022]

you mean if i chose any carbon atome i ll find systematiqualy a symetry plan between its substituant...!!!
conversly i find that all carbons were achiral