8.1 Introduction to Titrations Organic Compounds Organic compounds contain carbon atoms, usually bonded to other carbon atoms and hydrogen atoms. They may also contain other elements such as halogens, nitrogen, oxygen, phosphorus, and sulphur. Drawing Organic Compounds 9.1 Introduction to Titrations Hydrocarbons Hydrocarbons are compounds that contain only carbon and hydrogen atoms. Alkanes are hydrocarbons containing only single bonds. They are saturated meaning there is no room for other atoms to bond to the carbon skeleton. They have the general formual C n H (2n+2) Some examples: 9.1 Introduction to Titrations Naming Alkanes You need to know the following prefixes for naming 9.1 Introduction to Titrations Naming Branched Alkanes 9.1 Introduction to Titrations Structural Isomers Define Different compounds with different chemical properties, and yet they have the same molecular formula Examples 2 of 3 possible structural isomers 9.1 Introduction to Titrations Cycloalkanes Define Carbon atoms bonded to each other to form a cyclic structure Examples 9.1 Introduction to Titrations Cycloalkanes - Naming 9.1 Introduction to Titrations Alkenes Define Alkenes are hydrocarbons containing double bonds. They are unsaturated. Naming Rules the same as alkanes except that parent chain name ends in ene 9.1 Introduction to Titrations Alkenes - Isomers Geometric isomers - alkenes that have the same structure, but the orientation of the groups across the double bond are different. Geometric isomers are also called cis-trans isomers. Examples 9.1 Introduction to Titrations Alkynes Define Hydrocarbons containing triple bonds. They are unsaturated. They have the general formula C n H (2n-2) Naming Rules Same as for alkanes except parent chain ends in yne. Example Notes 9.1 Introduction to Titrations Aromatic Hydrocarbons Define Contain at least one benzene ring. Benzene Ring Six carbon atoms in a ring. It has a molecular formula C 6 H 6. Resonance Structures The electrons in the benzene molecule are delocalized, meaning that they are spread across more than one atom. In other words, there is more than one way to draw its Lewis structure. Equivalent Lewis structures are called resonance structures 9.1 Introduction to Titrations Naming Benzene For benzenes where only two branches exist on the ring, the three possible 1,2-, 1,3-, and 1,4- positions can also be indicated using the prefixes ortho, meta, and para respectively. These prefixes describe how close the branches are to each other on the benzene ring (Figure below). A benzene ring with one methyl branch is commonly called toluene. A benzene ring with two methyl branches is commonly called xylene.