25.3+Alkanes,+Alkenes,+&+Alkynes

Yes, there is only a one letter difference between all over these....

**Structural Isomers** are compounds with the same molecular formula but with different bonding arrangements. Alkanes [| Alkanes] are hydrocarbons that contain only single bonds of carbon.They are either straight-chain or branched-chain hydrocarbons. Another structure that alkanes can form in is **cycloalkanes**, which are rings or cycles. Their general formula is CnH2n, which differs from the straight-chain alkanes’ general formula, CnH2n +2. Whether straight-chained or a cycloalkane, alkanes other then combustion reactions have a low chemical reactivity because of the strength and lack of polarity of C-C and C-H bonds. When an isomer has a CH3 group that branches off the main chain it is named //iso//-isomer (example isobutene). **BUT** it becomes complicated when more isomers are added.

﻿Alkenes & Alkynes Alkenes are unsaturated hydrocarbons with at least one C=C bond. They are **geometric isomers**, which have the same molecular formula and groups bonded to one another, but differ in the spatial arrangeme nt of these groups. Alkenes have the capability of being geometic isomers due to the fact they have C=C bonds, which resist twisting. Alkynes are unsaturated hydrocarbons with one or more C≡ C bond. They unlike alkanes are highly reactive molecules. The naming of them is similar to alkanes expect you change -//ane// to //-yne//. **[|Addition Reactions]** is the most common chemical reaction alkenes and alkynes undergo, in which a reactant is added to the two atoms that form the multiple bond. Aromatic Hydrocarbons Aromatic Hydrocarbons are more stable then alkenes and alkynes due to the pi-electrons being delocalized in the pi-orbitals. They contain one or more benzene ring. Instead of addition reaction aromatic hydrocarbons complete **substitution reactions** in which one atom of a molecule is removed and replace by another atom or group of atoms.

**Work Cited**  "Alkene Reactivity." Michigan State University :: Department of Chemistry. Web. 23 Mar. 2011. . "Aromatic Hydrocarbons." Web. 23 Mar. 2011. . Brown, Theodore L., and H. Eugene LeMay. Chemistry: The Central Science. Upper Saddle River, NJ: Pearson Prentice Hall, 2008. Print. "Organic Nomenclature." Michigan State University :: Department of Chemistry. Web. 23 Mar. 2011.  .