What is the Difference Between Enantiomers and Stereoisomers

The main difference between enantiomers and stereoisomers is that enantiomers are a type of stereoisomer that are non-superimposable mirror images of each other whereas stereoisomers include both enantiomers and diastereomers.

Enantiomers and stereoisomers are terms used in the field of organic chemistry to describe different types of isomers, which are molecules with the same molecular formula but different arrangements of atoms.

Key Areas Covered

1. What are Enantiomers  
      – Definition, Features, Role
2. What are Stereoisomers
      – Definition, Features, Role
3. Relationship Between Enantiomers and Stereoisomers
      – Outline of Common Features
4. Difference Between Enantiomers and Stereoisomers
      – Comparison of Key Differences
5. FAQ: Enantiomers and Stereoisomers
      – Frequently Asked Questions

Key Terms

Enantiomers, Stereoisomers, Stereoisomerism

Difference Between Enantiomers and Stereoisomers - Comparison Summary

What are Enantiomers

Enantiomers are a branch of chemistry that explores the spatial arrangement of atoms within molecules. Enantiomers are a specific type of stereoisomer, which means they share the same molecular formula and connectivity of atoms but differ in their three-dimensional orientation. The distinguishing feature of enantiomers lies in their mirror-image relationship—they are non-superimposable, much like our left and right hands.

To understand enantiomers, consider a chiral molecule, one that lacks an internal plane of symmetry. Chirality arises when four different substituents surround a central carbon atom, creating a unique spatial arrangement. Enantiomers occur when two molecules are mirror images of each other, but not identical. This property makes them distinct entities with specific, albeit often subtle, differences in their interactions.

Enantiomers vs Stereoisomers

Figure 1: Enantiomers of Lactic Acid

The concept of chirality is important in fields such as pharmaceuticals, where the biological activity of a drug can be dramatically influenced by its stereochemistry. A classic example is thalidomide, a drug prescribed to pregnant women in the late 1950s. One enantiomer alleviated morning sickness, while the other caused severe birth defects. This tragic episode underscored the importance of considering stereochemistry in drug design and reinforced the need for enantiomerically pure compounds.

Chemists use various techniques to separate and analyze enantiomers, including chiral chromatography and asymmetric synthesis. Enantiopure compounds find applications in industries ranging from medicine to agriculture, ensuring precise control over their effects. The study of enantiomers continues to be a vibrant area of research, with implications not only in chemistry but also in the broader realms of biology and medicine. Understanding the intricacies of enantiomers opens doors to manipulating molecular interactions with precision, promising advancements in fields critical to human well-being.

What are Stereoisomers

Stereoisomers are found in organic chemistry, representing molecules with the same molecular formula and connectivity of atoms but differing in the spatial arrangement of atoms. This distinction leads to different properties and behaviors, even though their chemical compositions are identical. There are two main types of stereoisomers: geometric isomers and optical isomers.

Geometric isomers, also known as cis-trans isomers, arise when there is restricted rotation around a double bond or within a ring structure. In cis isomers, similar substituents are positioned on the same side of the molecule, while in trans isomers, they are on opposite sides. This geometric dissimilarity impacts the physical and chemical properties of the compounds. For example, cis and trans isomers may exhibit different melting points, boiling points, and reactivity.

Compare Enantiomers and Stereoisomers

Figure 2: Isomers

On the other hand, optical isomers, or enantiomers, result from the non-superimposable mirror images of a chiral molecule. Chirality arises when a molecule lacks a plane of symmetry, meaning it cannot be superimposed onto its mirror image. Enantiomers share identical physical properties but interact differently with plane-polarized light and exhibit distinct biological activities. One enantiomer might be therapeutically effective, while its mirror image could be inactive or possess adverse effects.

The study of stereoisomers is crucial in drug development, where slight differences in molecular arrangement can drastically impact a compound’s pharmacological properties. The separation and analysis of stereoisomers have practical applications in pharmaceuticals, agriculture, and materials science. Techniques like chromatography and chiral resolution methods play a pivotal role in isolating and studying these isomers.

Understanding stereoisomers provides valuable insights into the three-dimensional world of molecules, influencing fields ranging from medicine to materials engineering. As researchers delve deeper into the intricacies of stereochemistry, they uncover new opportunities for designing molecules with specific functions and properties.

Relationship Between Enantiomers and Stereoisomers

  • Enantiomers are a specific type of stereoisomers.
  • All enantiomers are stereoisomers, but not all stereoisomers are enantiomers.

Difference Between Enantiomers and Stereoisomers


Stereoisomers are a broad category of isomers where the atoms are connected in the same order, but the spatial arrangement of the atoms differs. Enantiomers are a type of stereoisomer that are mirror images of each other but cannot be superimposed onto one another.  


Enantiomers exhibit chirality, meaning they lack a plane of symmetry. Stereoisomers, in general, may or may not be chiral.

Optical Activity

Enantiomers rotate plane-polarized light equally but in opposite directions, resulting in equal and opposite specific rotations. Other stereoisomers may or may not exhibit optical activity.

FAQ: Enantiomers and Stereoisomers

Are enantiomers always chiral?

Yes, enantiomers are always chiral.

Are stereoisomers always chiral?

No, stereoisomers are not always chiral. Stereoisomers may be chiral or achiral.

Do enantiomers have 2 chiral centers?

Yes. They have 2 chiral centers.


The main difference between enantiomers and stereoisomers is that enantiomers are a type of stereoisomer that are non-superimposable mirror images of each other, whereas stereoisomers include both enantiomers and diastereomers.


1. “Enantiomers.” Byju’s.
2. “Stereoisomerism.” Encyclopedia Britannica.

Image Courtesy:

1. “Milchsäure Enantiomerenpaar” By NEUROtiker – Own work (Public Domain) via Commons Wikimedia
2. “Isomerism” By Vladsinger – Own work (CC BY-SA 3.0) via Commons Wikimedia

About the Author: Hasini A

Hasini is a graduate of Applied Science with a strong background in forestry, environmental science, chemistry, and management science. She is an amateur photographer with a keen interest in exploring the wonders of nature and science.

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