Properties of a free radical scavenger

Antioxidants are free radical scavengers and are able to reduce free radicals to make them stable. What I am interested in is why some molecules make for superb free radical scavengers and why others don't. For example why Vitamin E is a better scavenger then say methane (I know the comparison is silly but for arguments sake).


If its possible could the answer be as simplified as possible as I have not yet reached an advanced enough level in chemistry. I would also like to stay away from the biological aspect of free radicals would like the answer to be in purely chemistry terms.


