What is the perfect definition for chirality?

Question

Why is chirality defined differently for organic and inorganic compounds? Why are inorganic compounds deemed to be optically active if they have more than one of the same ligands attached to the central metal atom, but glycine is optically *inactive* for having two $\\ce{H}$ atoms attached to the carbon atom? Finally, what should be the criterion for chirality (optical activity) and the perfect definition for it?

Answer 1

Chirality is a molecule's ability to reflect polarizable due to the existence of two non-superimposable forms of the that molecule with the same molecular connectivity. Any molecule with an sp3 carbon connected to 4 unique substituents is deemed chiral.

The exception to this rule is if chirality is canceled out within the molecule due to intramolecular symmetry, "Meso" with one R and one S rotating polarizable light to the same magnitude in the opposite direction (+65 and -65). Note, meso molecules only exist in molecules with an even number of chiral carbons. Although meso molecules are achiral, the carbons themselves are still considered chiral.

Answer 2

Chirality is not defined differently. The reason that molecules are chiral might be different, but chirality has a pretty much fixed definition.

Chiral molecules (and objects) are not super imposable on their mirror images. Organic molecules are typically chiral because they have one or more chiral carbons. There is also axial chirality, when the molecule is chiral even though it lacks chiral centers. You could look up the wikipedia page on "axial chirality" if you are interested. Many Sophomore level exams completely ignore axial chirality, but there is the occasional professor who enjoys it.

In order for a chiral molecule to be optically inactive, it also must NOT be interconverting with it's enantiomer. Some special cases, such as amines with three unique groups and a lone pair, will do stuff like this. Again, this is rarely a focus of Sophomore level exams but it does occasionally come up.