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Doing a Minor Presentation of Parity/Chirality

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Vorde
#1
Nov14-12, 11:00 PM
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P: 784
Hello all.

I'm doing a small presentation on Chirality in my Chemistry class. As the teacher knows I'm really more of a physics/math kid, he said it was okay if I did my presentation on chirality in physics instead of the molecular stuff most people are doing. I knew a bunch before, and I've done some research since, but I was hoping you guys could tell me whether the gist of my 'presentation' is accurate enough.

Here it is, and this is the shortened version of course:
In chemistry it's easy to visualize Chirality as a process by which you find the 'mirror image' molecule of a specified compound. A question then arises as to how one would talk about Chirality of a fundamental particle which has no shape that can be altered by reflection. However, even though it doesn't seem like you could 'reflect' a fundamental particle, you can still define Chirality. If you remember, we talk about particles having 'up' or 'down' spin (this they've been taught).

Well, like it's name suggests, spin isn't just a number, it's a vector: meaning it's pointing in a direction. When a particle is moving, it's spin can either be pointing in the direction of motion or in the exact opposite direction as the particle is moving. If it's pointed in the same direction as the particle is moving then we call it a 'right handed' particle, and if it is moving in the opposite direction then we call it a 'left handed' particle. Now any particle can come in two varieties: left handed and right handed. And these are the two Chiralities of the particle, they are exactly the same in all respects except this. You'd think that, because no shape is changing, it wouldn't matter which Chirality the particle has, but that's not the case.

<Quick side-step onto the fundamental forces and the weak nuclear force - I'm confident about this part>

It turns out that the weak nuclear force will only interact with particles that are left handed! You can have two particles that are exactly identical except for the fact that they have different Chiralities, and one will interact freely with the weak nuclear force while the other will be totally ignored by it!
One of the big questions I have is that, knowing my audience, is it okay to ignore helicity and just talk about Chirality (eschewing the two together a bit)? I know it'll confuse everyone by trying to explain the difference between the two and I'd rather avoid that.

In general I want to make sure that a) I'm on target and b) I'm not oversimplifying.

Thanks for reading, and hopefully for helping me.
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DrDu
#2
Nov15-12, 01:36 AM
Sci Advisor
P: 3,596
The link between chemical and physical definition of chirality is not so straightforward.
Maybe the following article is interesting to you:

http://qjmed.oxfordjournals.org/cont...2/793.full.pdf
Vorde
#3
Nov15-12, 08:22 PM
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P: 784
Quote Quote by DrDu View Post
The link between chemical and physical definition of chirality is not so straightforward.
Maybe the following article is interesting to you:

http://qjmed.oxfordjournals.org/cont...2/793.full.pdf
First of all, thank you very much for that link; it was a really interesting read.

As for the rest of my little blurb, would it be within reason to say more or less what I'd said previously, but instead of ending where I did talk about some of the ways molecular Chirality plays a part in molecular formation?

DrDu
#4
Nov16-12, 01:52 AM
Sci Advisor
P: 3,596
Doing a Minor Presentation of Parity/Chirality

Quote Quote by Vorde View Post
Hello all.

One of the big questions I have is that, knowing my audience, is it okay to ignore helicity and just talk about Chirality (eschewing the two together a bit)? I know it'll confuse everyone by trying to explain the difference between the two and I'd rather avoid that.

In general I want to make sure that a) I'm on target and b) I'm not oversimplifying.

Thanks for reading, and hopefully for helping me.
I think that's ok. After all, helicity and chirality become equal for massless particles.


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