6.1.2 Homologous Series

• What group do successive members of a homologous series differ by?

  CH2
• A homologous series is a series of organic compounds that have the same functional group and follow a similar general formula
• Arrange the following alkanes in order of increasing molecular formula size:

  1️⃣ Methane (CH4)

  2️⃣ Ethane (C2H6)

  3️⃣ Propane (C3H8)
• What functional group is present in alcohols?

  -OH
• The general formula for alkanes is CnH2n+2
• Alkenes contain a C=C double bond.
• What is the functional group in carboxylic acids?

  -COOH
• Match the homologous series with its functional group:

  Alkanes ↔️ None

  Alkenes ↔️ C=C

  Alcohols ↔️ -OH

  Carboxylic Acids ↔️ -COOH
• The compounds in a homologous series follow a similar general formula
• What is the difference in molecular composition between successive members of a homologous series?

  CH2
• Physical properties of homologous series compounds change gradually as molecular size increases.
• What is the functional group in alkanes?

  None
• The functional group in alkenes is the C=C double bond.
• Alcohols contain the -OH hydroxyl group.
• What is the functional group in carboxylic acids?

  -COOH
• Match the characteristic with its description in a homologous series:

  Same functional group ↔️ All compounds have the same functional group

  Similar general formula ↔️ Compounds follow a similar formula

  Differ by CH2 ↔️ Successive members differ by a CH2 group

  Gradual changes ↔️ Physical properties change gradually
• What is the general formula for alkanes?

  $C_{n}H_{2n + 2}$
• Successive members in a homologous series differ by a CH2 group.
• Physical properties in a homologous series change gradually as the molecular size increases.
• What is the definition of a homologous series?

  Organic compounds with same functional group
• Arrange the alkanes in order of increasing carbon atoms:

  1️⃣ Methane (CH4)

  2️⃣ Ethane (C2H6)

  3️⃣ Propane (C3H8)
• Which are common examples of homologous series?

  Alkanes, alkenes, alcohols, carboxylic acids
• Homologous series share the same functional group and general formula.
• Match the homologous series with its functional group:

  Alkanes ↔️ No functional group

  Alkenes ↔️ C=C double bond

  Alcohols ↔️ -OH hydroxyl group

  Carboxylic Acids ↔️ -COOH carboxyl group
• What is the general formula for carboxylic acids?

  $C_{n}H_{2n + 1}COOH$
• Homologous series include alkanes, alkenes, alcohols, and carboxylic acids
• Match the homologous series with its functional group:

  Alkanes ↔️ No functional group

  Alkenes ↔️ C=C double bond

  Alcohols ↔️ -OH hydroxyl group

  Carboxylic Acids ↔️ -COOH carboxyl group
• The general formula for alkanes is C_{n}H_{2n + 2}</latex>
• The functional group in alkenes is the C=C
• The general formula for alcohols is $C_{n}H_{2n + 1}OH$
• Homologous series share the same functional group and follow similar general formulas.
• The general formula for alkenes is C_{n}H_{2n}</latex>
• The functional group in alcohols is the -OH
• The general formula for carboxylic acids is $C_{n}H_{2n + 1}COOH$
• All members of a homologous series contain the same functional group
• Successive members of a homologous series differ by a CH2 group.
• Physical properties within a homologous series change gradually as molecular size increases.
• Arrange the following trends in physical properties of homologous series in order of increasing molecular size:

  1️⃣ Boiling Point

  2️⃣ Melting Point

  3️⃣ Density

  4️⃣ Solubility
• The boiling point of a homologous series increases due to increased intermolecular forces
• The solubility of a homologous series generally decreases as molecular size increases.