Why are some molecules chiral and others achiral?

[Gannon]

I really don't understand any of this. I already know the answers to these, but I don't know why they are chiral or achiral. Any help is appreciated.

http://i57.photobucket.com/albums/g231/Paylardo/Chriality.jpg

The "HO" on the far left was cut off. It is just another hydroxyl group.

 

[chemisttree]

do you understand the term 'meso'? Sometimes it helps to build models of the structures and their mirror image to see if they are superimposable.

 

[Gannon]

I've built models, but when it comes to a test I'll need to be able to see that they can superimpose in more ways than one... I've seen meso further in the book where I'm studying, but other than that I know nothing about it. There is something about mirror planes and inversion centers that I understand a little bit, but I can't apply them to these.

 

[srinivass]

Derivation on angular acceleration

 

[Gannon]

I know how to find stereocenters; would that help me?

 

[chemisttree]

That is where you start. Familiarity with models will help you visualize the structures (without models) during your test. This is common practice in undergrad organic chem.