Hydrocarbons Read pp

Hydrocarbons Compounds that contain ONLY hydrogen and carbon atoms. There are three kinds of hydrocarbons: Alkanes – single bond between carbon atoms Alkenes – one or more of the carbons have double bond(s) Alkynes – one or more of the carbons have triple bond(s)

# of C atomsPrefixAlkane IUPAC Name 1meth-methane 2eth-ethane 3prop-propane 4but-butane 5pent-pentane 6hex-hexane 7hept-heptane 8oct-octane 9non-nonane 10dec-decane

Structural Formulas for Alkanes 1.Draw the # of C atoms in a straight line according to prefix 2.Fill in the hydrogen atoms using single bond lines. Remember, Carbon has 4 valence electrons, so it holds 4 bonds!! ethane octane

Naming Alkanes 1.Count the # of carbon atoms  prefix 2.Write in the suffix “ane” (single-bonds only) butaneheptane

Structural Formulas – Alkenes and Alkynes 1.Draw the # of C atoms in straight line according to prefix 2.The number in front of the IUPAC name tells you which C atom the double/triple bond is located. 3.Fill in the H atoms. Remember, each C atom has 4 bonds, so double-check! 2-hexene1-pentyne

Naming Alkenes and Alkynes 1.Look at the structural formula. A double bond tells you it’s an alkene. A triple bond tells you it’s an alkyne. 2.Count # of C atoms  prefix 3.Read left-right and right-left. Take the lowest # that the C atom is located on. This # goes in front of prefix 4.Write ‘ene’ if alkene or ‘yne’ if alkyne.

Naming Alkenes and Alkynes H H H H H-C-C-C-C=C-H1-pentene H H H H H H H H H H-C-C-C-C-C≡C-C-C-H3-octene H H H H H H

Isomers Compounds that have the SAME molecular formula (eg. C4H8), but have different shapes. This leads to differences in chemical and/or physical properties. 1-pentene2-pentene BP: 30°CBP: 37°C

Properties of Hydrocarbons Alkanes are saturated. It cannot accept any more atoms/molecules. Alkenes and alkynes are unsaturated. Their double/triple bonds can be broken down to accept more atoms/molecules (see Addition Reactions) The longer the hydrocarbon (more C atoms), the more energy it takes to break it apart. The more C atoms, the higher the boiling point.

Combustion Reactions of Hydrocarbons When a hydrocarbon reacts with oxygen gas to form two products: CO 2 and H 2 O. Write a balanced equation to show the combustion of 1-pentane. C 5 H O 2  5CO 2 + 6H 2 O

Addition Reactions of Alkenes and Alkynes When a compound is added across a double or triple bond. This compound can be: A halogen (HCl, HBr, HI, HF) Water (H 2 O) Hydrogen gas (H 2 ) Note: The double bond becomes a single bond; the triple bond becomes a double bond.

Draw a structural formula equation for the addition reactions: a)2-butene and hydrogen bromine (HBr) H H H H H H H H H-C-C=C-C-H + H-Br  H-C-C-C-C-H H H H H Br H a)2-pentyne and water (H 2 O) H H H H H H H-C-C≡C-C-C-H + H-OH  H-C-C=C-C-C-H H H H H H OH H H

c) 2-heptene and hydrogen gas (H 2 ) H H H H H H H H H H H H H H H-C-C=C-C-C-C-C-H + H-H  H-C-C-C-C-C-C-C-H H H H H H H H H H H H H