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Chiral Molecule

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    • \( \newcommand{\vecs}[1]{\overset { \scriptstyle \rightharpoonup} {\mathbf{#1}} } \) \( \newcommand{\vecd}[1]{\overset{-\!-\!\rightharpoonup}{\vphantom{a}\smash {#1}}} \)\(\newcommand{\id}{\mathrm{id}}\) \( \newcommand{\Span}{\mathrm{span}}\) \( \newcommand{\kernel}{\mathrm{null}\,}\) \( \newcommand{\range}{\mathrm{range}\,}\) \( \newcommand{\RealPart}{\mathrm{Re}}\) \( \newcommand{\ImaginaryPart}{\mathrm{Im}}\) \( \newcommand{\Argument}{\mathrm{Arg}}\) \( \newcommand{\norm}[1]{\| #1 \|}\) \( \newcommand{\inner}[2]{\langle #1, #2 \rangle}\) \( \newcommand{\Span}{\mathrm{span}}\) \(\newcommand{\id}{\mathrm{id}}\) \( \newcommand{\Span}{\mathrm{span}}\) \( \newcommand{\kernel}{\mathrm{null}\,}\) \( \newcommand{\range}{\mathrm{range}\,}\) \( \newcommand{\RealPart}{\mathrm{Re}}\) \( \newcommand{\ImaginaryPart}{\mathrm{Im}}\) \( \newcommand{\Argument}{\mathrm{Arg}}\) \( \newcommand{\norm}[1]{\| #1 \|}\) \( \newcommand{\inner}[2]{\langle #1, #2 \rangle}\) \( \newcommand{\Span}{\mathrm{span}}\)\(\newcommand{\AA}{\unicode[.8,0]{x212B}}\)

    A chiral molecule is a molecule that is not superimposable on its mirror image.

    eg. 1:

    chiralmolecule1.png

    Molecule 1 is not superimposable on its mirror image and, therefore, is chiral.

    eg. 2:

    chiralmolecule2.png

    Molecule 2 is not superimposable on its mirror image and, therefore, is chiral.

    An achiral molecule is a molecule that is superimposable on its mirror image.

    eg. 1:

    achiralmolecule1.png

    Molecule 3 is superimposable on its mirror image and, therefore, is achiral.

    eg. 2:

    achiralmolecule2.png

    Molecule 4 is superimposable on its mirror image and, therefore, is achiral.

    Alternatively, an achiral molecule is a molecule that has at least one plane of symmetry.

    eg. 1:

    chiralmolecule3.png

    The vertical plane that bisects the bromine atom and the methyl group, which is the plane of the screen, is a plane of symmetry. Thus, 3 is achiral.

    eg. 2:

    chiralmolecule4.png

    The vertical plane that bisects the molecule perpendicular to the plane of the screen is a plane of symmetry. Thus, 4 is achiral.

    A chiral molecule has no plane of symmetry.

    eg. 1

    chiralmolecule5.png

    1 is chiral and has no plane of symmetry.

    eg. 2:

    chiralmolecule6.png

    2 is chiral and has no plane of symmetry.

    Although relatively rare, molecules do exist that have no plane of symmetry but is achiral.

    eg:

    chiralmolecule7.png

    Thus, presence of a plane of symmetry is not a foolproof method to determine whether a molecule is chiral or achiral.

    This page titled Chiral Molecule is shared under a All Rights Reserved (used with permission) license and was authored, remixed, and/or curated by Gamini Gunawardena via source content that was edited to the style and standards of the LibreTexts platform; a detailed edit history is available upon request.

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