Hydrocarbons Chapter 8:
What is carbon chemistry? • Compounds containing Carbon make up 90% of all chemicals and form the basis of living things • Organic chemistry is the study of Carbon compounds
How does Carbon form so many compounds? The electronic configuration of carbon is 1s22s22p2. It can form a wide variety of compounds because: • each carbon atom has four valence electrons, all available for bonding with other atoms • a carbon atom can form strong covalent bonds with other carbon atoms • bonds between carbon atoms can be single or multiple.
Hydrocarbons • Compounds made up of Hydrogen and Carbon are known as Hydrocarbons • Hydrocarbons can be classified into several series or families • The first series is known as the “alkanes”
Alkanes • Are a family that consist of carbon and hydrogen only • They contain only single bonds • CnH2n+2 • Compounds that differ only by –CH2- belong to the same homologous series • Compounds of the same homologous series share the same similar properties
Representing Alkanes We use structural formulas to represent hydrocarbons You will notice that each carbon atom: • forms a single covalent bond to four other atoms • each hydrogen atom forms a single covalent bond to one carbon atom • the four atoms bonded to each carbon atom are arranged in a tetrahedral manner around the carbon.
Structural Isomers When we come to draw a structural formula for C4H10, however, there are two possible arrangements that satisfy the bonding requirements of each of the four carbon atoms and ten hydrogen atoms
Structural Isomers These two compounds are structural isomers. That means that they have the same molecular formula (C4H10) but a different arrangement of their atoms. Structural isomers have similar chemical properties but differ in some physical properties such as melting and boiling temp. As molecules become larger, the number of possible arrangements of atoms increases rapidly.
Saturated Hydrocarbons The alkanes are known as saturated hydrocarbons. Because there are only single bonds between carbon atoms, they are ‘saturated’ with hydrogen atoms. Carbon and hydrogen can also form families of compounds in which there are double or triple bonds between carbon atoms. These compounds are unsaturated as they do not contain the maximum number of H atoms.
Naming Alkanes Alkanes use the prefix relevant to the number of Carbons, and ends in “ane”. Four things you may be asked for: • Name the compound • Write the molecular formula • Draw the Structural formula • Write the condensed structural formula
Alkenes The alkenes form a new homologous series. Their members differ by -CH2- and contain a single double bond between two carbon atoms and share similar chemical properties. CnH2n Alkenes are unsaturated as they contain less than the maximum amount of Hydrogens possible. They are named using the same prefix and end in “ene”. Isomers exist in Alkenes as well. Isomers can be branched, straight chain or even a different position of the double bond.
Your Turn: • Complete the Handout • Name the alkanes • Draw the Structural formula • Write the semi-structural (condensed) formula • Write the molecular formula • Chapter 8 Review Questions • Q 2, 3, 4, 5, 6 • Complete the second handout of challenge questions Don’t forget – SACT due next Wednesday!! Check the blog and keep up to date!!