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Chiral and Achiral Molecules

In stereoisomers, the difference lies in the spatial arrangement of atoms rather than the order in which they are connected.

Chiral and Achiral Molecules

In stereoisomers, the difference lies in the spatial arrangement of atoms rather than the order in which they are connected. The most fascinating stereoisomers are those that are mirror images of each other, parallel molecules. There is a concept known as chirality that determines the existence of these molecules. The word "chiral" was derived from the Greek for hand, since each hand is a mirror image of the other.

Achiral is the opposite of chiral. An achiral object can be superimposed with its mirror image. It is achiral, for instance, to have two sheets of paper. As opposed to our hands, chiral molecules cannot be superimposed. Both of your hands should be pointing in the same direction. Give this some time. Does it seem that they aren't lining up perfectly? Molecules are the same way.

Mirror images of chiral molecules cannot be superimposed on each other- they don't line up perfectly. They are known as enantiomers. So, what is so special about chiral molecules? Enantiomers and their chiral molecules will have the same physical and chemical properties (boiling point, melting point, polarity, etc.). DNA is one example of chiral molecule, as are amino acids and sugars in our bodies. Even though our hands seem to serve the same purpose, most people have trouble using both hands simultaneously to write. A chiral molecule and its interactions function similarly. It's similar to how your left hand won't fit into your right glove if you have two enantiomers of the same molecule.

In order to differentiate themselves from their mirror images, enantiomers must possess certain properties. These planes lack a plane of symmetry or a plane of internal reflection. Hence, mirror image halves cannot be produced from chiral molecules. It is also optically active. In the chemistry of life, organic compounds play an essential role. They are molecules created around atoms of carbon. They are important because of the energy they carry, primarily in the form of potential energy between atoms. Because a change in atomic arrangement can greatly affect such potential force, it is critical to know the concept of an isomer, a molecule that shares the same atomic make-up but differs in structural arrangements. In this article, we discuss a particular isomer called a stereoisomer, which is chiral.

In modern organic chemistry, steroisomerism and chirality, which describe the structure and function of many organic molecules, are crucial concepts that contribute to a greater understanding of the physical and theoretical reasons for the energy embedded within each of these molecules. Contrary to other isotopic compounds created by different atomic connections, stereoisomerism generally maintains the same number of atoms and types of elements as well as equal atomic connections.

How do stereoisomers differ from other compounds? The learner must be able to think and visualize in both two-dimensional and three-dimensional space in order to answer this question. The difference in the spatial arrangement between the atoms in stereoisomers makes them isomers.


Among the stereoisomer types discussed in this article, this one is an essential mirror-image, non-superimposable type. An excellent example can be found in Figure; notice how the gray plane in the middle demotes the mirror plane.

The atomic arrangements will not be equal for the left and right molecules if they are flipped over. Molecules have a relationship similar to that of left and right hands, and are called 'handed'. The article suggests that the reader utilize the 'hand' example since this can be counter-intuitive. Face your palms upwards, and clasp your hands together. Flip each side over. The palm of one hand should be shown, while the back of the other. Neither are the same, nor can they be superimposed.


It basically means that chiral molecules are mirror images that cannot be superimposed, and therefore say that chiral molecules are molecules whose mirror image (they must have one) is different from themselves. A molecule's chirality can be determined by several overlapping conditions. Here are two examples of molecules with differing chirality, achiral and chiral. A chiral molecule is distinguished by the presence of two atoms of the same element. If one creates a bisecting plane through the other two atoms, the images on either side are the same.

The molecule is referred to as achiral in this case. In other words, chiral molecules can be distinguished from achiral molecules by observing the presence of the bisecting plane between them. In all chiral molecules, no matter how complex or simple, there is no bisecting plane. In general, no molecules containing atoms of different elements can be achiral. Stereoisomerism is used to explain one type of its kind with chirality, which is a simple, but essential concept. In modern organic chemistry, chirality means that the chemical properties of a molecule differ from those of its mirror image.
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Ankur Choudhary is India's first professional pharmaceutical blogger, author and founder of, a widely-read pharmaceutical blog since 2008. Sign-up for the free email updates for your daily dose of pharmaceutical tips.
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