# How many stereocenters in the compound?

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#### swtseselala

##### Full Member
7+ Year Member
Need help!! Mcat next week and I cannot find the answer to this question anywhere.

I know the formula is 2^n. I pretty much know how to find them (should have 4 different substituents bound to central chiral atom) But do Nitrogens count as a chiral center or just the Carbons?

Need help!! Mcat next week and I cannot find the answer to this question anywhere.

I know the formula is 2^n. I pretty much know how to find them (should have 4 different substituents bound to central chiral atom) But do Nitrogens count as a chiral center or just the Carbons?

Long answer yes, in the world of Orgo you can have Nitrogen atoms (which can be electronically tetrahedral) that are considered chiral. This also sometimes occurs with Si and P. The lone pairs can be considered as one of the 4 different groups.

Short answer NO, the AAMC has never, from what I have seen in the last 10 years expected students to use non-carbons as chiral centers. In all of the AAMC material released since 2001, I have never come across a Question that considered a non-carbon atom as a chiral center when counting. For the purposes of the MCAT, chiral = carbon.

Hope this helps. Good Luck!

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Usually when they should a big molecule as ask how many chiral centers, all you have to do is count the number of carbons with a wedge or dash attached to them. I've yet to see a problem where it was not that simple.

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Usually when they should a big molecule as ask how many chiral centers, all you have to do is count the number of carbons with a wedge or dash attached to them. I've yet to see a problem where it was not that simple.

This is a poor strategy as two substituents could be identical.

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Long answer yes, in the world of Orgo you can have Nitrogen atoms (which can be electronically tetrahedral) that are considered chiral. This also sometimes occurs with Si and P. The lone pairs can be considered as one of the 4 different groups.

Short answer NO, the AAMC has never, from what I have seen in the last 10 years expected students to use non-carbons as chiral centers. In all of the AAMC material released since 2001, I have never come across a Question that considered a non-carbon atom as a chiral center when counting. For the purposes of the MCAT, chiral = carbon.

Hope this helps. Good Luck!

This will help enormously for my mcat. Testing Sept 23rd. Thank you!

you can have Nitrogen atoms (which can be electronically tetrahedral) that are considered chiral. This also sometimes occurs with Si and P. The lone pairs can be considered as one of the 4 different groups.

This is only in extreme cases where Nitrogen cannot flip the plane of its lone pair. I can count on the fingers of my two hands how many molecules I have seen act like that.