Structural isomers have the same molecular formula but differ in how the atoms are bonded to each other; that is, their attachment style is different.
Such molecules that differ by bonds while still having the same molecular formula are also known as constitutional isomers.
Learning Objective: To learn about tautomerism, a subtype of structural isomerism.
Skill Level – Intermediate
Prerequisites:
Learning Objective: To learn about metamerism, a subtype of structural isomerism.
Skill Level – Intermediate
Prerequisites:
Learning Objective: To learn about functional isomerism, a subtype of structural isomerism.
Skill Level – Intermediate
Prerequisites:
Learning Objective: To learn about ring–chain isomerism, a subtype of structural isomerism.
Skill Level – Intermediate
Prerequisites:
Learning Objective: To learn about positional isomerism, a subtype of structural isomerism.
Skill Level – Intermediate
Prerequisites:
Learning Objective: To learn about chain or nuclear isomerism, a subtype of structural isomerism.
Skill Level – Intermediate
Prerequisites:
Learning Objective: To learn what is structural isomerism and its subtypes.
Skill Level – Intermediate
Chapter: Structural Isomerism
Structural Isomerism | Stereoisomerism |
|---|---|
Isomers have the same molecular formula but differ in how the atoms are bonded to each other. | Isomers have the same molecular formula and bonding arrangement; however, they differ in how the atoms are arranged in 3-dimensional space (spatial orientation) with respect to each other. |
Such molecules that differ by bonds while still having the same molecular formula are also known as constitutional isomers. |
The discovery of isomerism marked the advent of structural chemistry, where it became significantly important to establish structural formulas, welcome the abundance of structurally diverse compounds, classify them, and study their individual properties and impacts.
Around the early 1800s, scientists began to notice the presence of isomerism in all types of compounds; however, at the time, it was referred to using different names.
The term allotrope was used to describe different varieties of an element that existed in different physical forms, such as diamond or graphite for carbon or monoclinic or rhombic for sulfur. Polymorphism was used to explain compounds that occurred in more than one crystalline form, like aragonite and calcite, both crystalline forms of calcium carbonate.
Accidental discoveries and insatiable curiosity fuel chemistry.
One such significant discovery is of isomerism, which also occurred around the period when the faith in vitalism, a belief that organic molecules must only come from living organisms, was dwindling.
It was a pleasant surprise to learn that urea, a by-product of urine produced by human kidneys, could also be synthesized by heating ammonium cyanate, an inorganic compound.
| n- | iso- | neo- | sec- or s- | tert- or t- | |
|---|---|---|---|---|---|
| Stands for | normal | isomer | Greek for new | secondary | tertiary |
| Structure | The carbon chain is continuous without any branching; therefore, it represents a straight-chain alkane. | Iso- prefix indicates branching of the straight chain alkane.
|
Prerequisite Reading: Structural Isomerism, Types of Hydrogen, Free radical halogenation
1) Functional Isomers are compounds that have same molecular formula but different functional groups.