# What is the perfect definition for chirality?

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? Could anyone explain how $\\ce{$cis$-[PtCl2(en)2]^2+}$ is optically active, but the $trans-$isomer is not?