Figure 1.

Chirality and handedness. (a) A pair of shoes is chiral and handed. The right shoe is the mirror image of the left shoe, but none of the mirror images coincide with itself; (b) potatoes are chiral because there exists no mirror operation that transform them into themselves; however, they are not handed, and there exist no left- or right-handed potatoes; (c) a rotating ball can exhibit a left (clockwise) or a right (“handed”) (anti-clockwise) rotation and thus it may be called handed; however, one of its mirror images coincided with itself and therefore it is not chiral but helical.