Hydrocarbon Isomers

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Isomers Noun

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[eye-so-merz]

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Isomers

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Compounds that possess the same molecular formula but have different arrangements of atoms in their molecular structures.

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Example: This image shows two molecules with the same atoms but different structures: a straight 'linear' chain and a 'branched' chain, demonstrating the concept of isomers.

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Structural Isomers Noun

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[struk-cher-ul eye-so-merz]

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Structural Isomers

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Molecules with the same chemical formula where atoms are connected in a different order, resulting in distinct properties.

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Example: This image shows two molecules, butane and iso-butane. Both have the same chemical formula (C4H10) but their atoms are connected in different arrangements.

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Stereoisomers Noun

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[ster-ee-oh-eye-so-merz]

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Stereoisomers

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Isomers in which atoms are bonded in the same sequence but are arranged differently in three-dimensional space.

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Example: This image shows two molecules that have the same atoms and connections, but their attached groups (CH3) are arranged differently in 3D space, defining them as stereoisomers.

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Geometric Isomers Noun

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[jee-oh-met-rik eye-so-merz]

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Geometric Isomers

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Stereoisomers that arise from different spatial arrangements of groups around a rigid bond, such as a carbon-carbon double bond.

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Example: This image shows two geometric isomers. In the 'cis' form, the CH3 groups are on the same side; in the 'trans' form, they are on opposite sides.

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cis- Adjective

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[sis]

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cis-

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A prefix used in chemical nomenclature to indicate that functional groups are on the same side of a double bond.

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Example: This diagram of cis-2-Butene shows that in a 'cis' isomer, the main groups (CH3) are on the same side of the carbon-carbon double bond.

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trans- Adjective

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[tranz]

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trans-

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A prefix used in chemical nomenclature to indicate that functional groups are on opposite sides of a double bond.

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Example: In trans-isomers, similar groups (like CH3) are on opposite sides of the carbon-carbon double bond, unlike in cis-isomers where they are on the same side.

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Optical Isomers Noun

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[op-ti-kul eye-so-merz]

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Optical Isomers

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Stereoisomers that are non-superimposable mirror images of each other, often containing an asymmetric carbon atom.

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Example: This image shows that optical isomers are like your hands: they are mirror images of each other but cannot be perfectly stacked or superimposed.

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Chirality Noun

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[ky-ral-i-tee]

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Chirality

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The geometric property of a molecule that is non-superimposable on its mirror image, resulting in right- and left-handed forms.

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Example: This image shows that just like your left and right hands are mirror images but can't be perfectly stacked, some molecules, called chiral molecules, are non-superimposable mirror images of each other.

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dextro- (d-) Adjective

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[dex-troh]

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dextro- (d-)

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A prefix identifying the optical isomer that rotates the plane of polarized light in a clockwise direction.

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Example: This diagram shows how a 'dextro-' chemical in a liquid can bend light in a clockwise (right-turning) direction as the light passes through it.

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levo- (l-) Adjective

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[lee-voh]

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levo- (l-)

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A prefix identifying the optical isomer that rotates the plane of polarized light in a counterclockwise direction.

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Example: This diagram shows how a polarimeter works. When polarized light passes through a sample containing a 'levo-' isomer, the light's orientation is rotated left.