Structural isomerism (or constitutional isomerism) is a form of isomerism in which molecules with the same molecular formula have atoms bonded together in different orders, as opposed to stereoisomerism. In chemistry, isomers are molecules with the same chemical formula and often with the same kinds of bonds between atoms, but in which the atoms are arranged differently. ... In chemistry, a molecule is an aggregate of two or more atoms in a definite arrangement held together by chemical bonds [1] [2] [3] [4] [5]. Chemical substances are not infinitely divisible into smaller fractions of the same substance: a molecule is generally considered the smallest particle of a pure... A chemical formula (also called molecular formula) is a concise way of expressing information about the atoms that constitute a particular chemical compound. ... Atomic redirects here. ... Main article: stereochemistry Stereoisomerism is the arrangement of atoms in molecules whose connectivity remains the same but their arrangement in space is different in each isomer. ...

Three three categories of constitutional isomers are skeletal, positional, and functional isomers.

In skeletal isomerism (or chain isomerism) components of the (usually carbon) skeleton are distinctly re-ordered to create different structures. For example 3-methylpentane is a chain isomer of 2-methylpentane. Pentane exists as three isomers: n-pentane, isopentane and neopentane. Pentane (also known as amyl hydride or skellysolve) is an alkane hydrocarbon with the chemical formula CH3(CH2)3CH3. ... Pentane also known as amyl hydride or skellysolve is an alkane hydrocarbon with the chemical formula CH3(CH2)3CH3. ... Pentane also known as amyl hydride or skellysolve is an alkane hydrocarbon with the chemical formula CH3(CH2)3CH3. ...

In position isomerism a functional group changes position on the chain. In the diagram, pentan-2-ol has become pentan-3-ol. Many aromatic isomers exist because substituents can be positioned on different parts of the benzene ring. Only one isomer of phenol or hydroxybenzene exists but cresol or methylphenol has three isomers where the additional methyl group can be placed on three different positions on the ring. Xylenol has one hydroxyl group and two methyl groups and a total of 6 isomers exist. In organic chemistry, functional groups are specific groups of atoms within molecules, that are responsible for the characteristic chemical reactions of those molecules. ... In chemistry, an aromatic molecule is one in which electrons are free to cycle around circular arrangements of atoms, which are alternately singly and doubly bonded to one another. ... Phenol, also known under an older name of carbolic acid, is a colourless crystalline solid with a typical sweet tarry odor. ... Cresols are organic chemical compounds which are methylphenols. ... Xylenol or dimethylphenol is a benzene derivative with two methyl groups and a hydroxyl group. ...

In functional group isomerism a functional group splits up and becomes a different group. Here is an example of functional group isomerism: take cyclohexane, C₆H₁₂ and 1-Hexene, also C₆H₁₂. These two are considered functional group isomers because cyclohexane is an alkane and 1-Hexene is an alkene. Both must have the same molecular formula. Image File history File links File history Legend: (cur) = this is the current file, (del) = delete this old version, (rev) = revert to this old version. ... Cyclohexane is a cycloalkane with the molecular formula C6H12. ... 1-hexene is a higher olefin, or alkene, with a formula C6H12. ... Chemical structure of methane, the simplest alkane Alkanes are chemical compounds that consists only of the elements carbon (C) and hydrogen (H) (i. ... The chemical structure of ethylene, the simplest alkene. ... A chemical formula (also called molecular formula) is a concise way of expressing information about the atoms that constitute a particular chemical compound. ...

Image File history File links C6H12_isomers. ...

References

• Clark, Jim. "Structural isomerism" in Chemguide, n.l., 2000, December 7Web article