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Subject - Organic Chemistry

Based on their behavior towards linear-polarized light, chemical compounds can be divided into two groups: they either rotate the plane of the light or they do not. Optically active compounds belong to the first group. Their behavior is caused by special symmetry properties inherent in their crystals or molecules. K. Mislow proposed to use the term chirality (handedness, from the Greek cheir, hand) which was coined in 1904 by Lord Kelvin for the molecular property that gives rise to the optical activity. V. Prelog deserves credit for mathematically embedding chirality into group theory. Like a hand, a molecule is chiral if it is non-superposable on its mirror image. Symmetry considerations are used to decide if a molecule is chiral or achiral.

See also: optical activity

Subject - General Chemistry

Molecular systems and other geometrical objects that exclusively allow rotations as symmetry operations are called dissymmetric or chiral.

Recommended Learning Units

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This learning unit describes the drawing of molecules and the naming of the absolute configuration with the help of the Fischer projection.

Molecules with Several Chirality Centers and Meso CompoundsLevel 220 min.

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ChiralityLevel 230 min.

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Additional Chirality ElementsLevel 230 min.

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This learning unit explains chirality elements that are not chirality centers, such as chirality axes, helices and chirality planes, as well as the naming of absolute configuration of these chirality elements. In addition, heteroatoms as chirality centers are described.