2.4.2 Alkanes and Alkenes

• The number of hydrogen atoms in alkanes is twice the number of carbon atoms plus two.

  True
• Steps for naming alkanes using IUPAC conventions

  1️⃣ Identify the longest carbon chain

  2️⃣ Name the parent alkane

  3️⃣ Number the chain from the nearest branch

  4️⃣ Identify and name substituents

  5️⃣ Combine the names
• The general formula of alkanes is C_n H_{2n+2}
• The general formula for alkanes is C_{n} H_{2n+2}.
• Match the molecular formula with its structural isomers:

  $C_{4} H_{10}$ ↔️ Butane, Isobutane

  $C_{5} H_{12}$ ↔️ Pentane, Isopentane, Neopentane
• The alkane CH3CH2CH(CH3)CH2CH3 is named 3-methylhexane.


  True
• Steps involved in the combustion of alkanes

  1️⃣ Alkanes react with oxygen

  2️⃣ Produce carbon dioxide and water

  3️⃣ Release heat in an exothermic reaction
• Alkenes have the general formula C_{n} H_{2n}.


  True
• What is the general formula for alkenes?

  $C_{n}H_{2n}$
• Match the bond type with the corresponding compound:

  Single bond ↔️ Alkanes

  Double bond ↔️ Alkenes
• The general formula for alkenes highlights that they are unsaturated hydrocarbons.

  True
• What type of hydrocarbons are alkanes?

  Saturated
• What is meant by isomerism in alkanes?

  Structural arrangements
• What is the name of a straight-chain alkane with 4 carbon atoms?

  Butane
• Alkanes are saturated hydrocarbons composed solely of carbon and hydrogen atoms.
• What type of bonds do saturated alkanes have?

  Single bonds
• The first step in alkane nomenclature is to identify the longest carbon chain.
• The boiling point of alkanes increases with increasing molecular size.
• Match the reaction type with its conditions and products:

  Combustion ↔️ Oxygen and heat ||| Carbon dioxide and water

  Substitution ↔️ Halogen and UV light ||| Halogenated alkanes and halogen acids

  Cracking ↔️ High temperature and pressure ||| Smaller alkanes and alkenes
• Alkenes are classified as unsaturated hydrocarbons due to the presence of a carbon-carbon double bond.
• What makes alkenes polar molecules?

  Carbon-carbon double bond
• What is the general formula for alkanes?

  C_{n}H_{2n+2}</latex>
• Match the component in the alkane general formula with its meaning:

  $C_{n}$ ↔️ Represents n carbon atoms

  $H_{2n + 2}$ ↔️ Represents 2n+2 hydrogen atoms
• Conformational isomers result from rotation around single bonds in alkanes.


  True
• The parent alkane for a carbon chain with 6 carbons is hexane
• Substituents in alkane nomenclature are listed alphabetically with their carbon number location.

  True
• Larger alkanes have higher melting points due to their ability to pack more closely together.


  True
• The combustion of alkanes is a highly exothermic reaction.


  True
• Alkenes are polar molecules due to the presence of a carbon-carbon double bond.


  True
• Alkenes are a class of unsaturated hydrocarbons composed of carbon and hydrogen atoms, with at least one carbon-carbon double bond.
• The general formula for alkenes is C_n H_{2n}
• What is the IUPAC name for the alkene with the structure CH3CH=CHCH2CH3?

  Pent-2-ene
• What is the general formula for alkanes?

  $C_{n} H_{2n + 2}$
• Steps in identifying isomers of alkanes

  1️⃣ Determine the molecular formula

  2️⃣ Draw possible structural arrangements

  3️⃣ Identify structural isomers

  4️⃣ Recognize conformational isomers
• Alkanes exhibit more geometric isomers compared to alkenes.

  False
• Conformational isomers differ due to bond rotation
• What is the parent alkane for a 6-carbon chain?

  Hexane
• Why does the boiling point of alkanes increase with molecular size?

  Stronger Van der Waals forces
• Combustion of alkanes produces carbon dioxide and water
• The process where large alkanes break down into smaller alkanes and alkenes is called cracking