• In order to study the physical properties and chemical reactions of organic compounds, they are classified into groups of compounds called the homologous series..

• The same general formula..
• The same functional group.
• The same chemical properties.
• Consecutive members differ by one carbon atom and two hydrogen atoms (\(CH_2\) or relative molecular mass = 14).
• Physical properties that gradually change from one member to the next.
• The homologous series that will be learned in this topic is as shown below:
  • Alkane
  • Alkene
  • Alkyne
  • Alcohol
  • Carboxylic acid
  • Ester

• Alkane: a group of organic compounds that are saturated hydrocarbons. 
• A single carbon atom can form 4 bonds with other atoms.
• The general formula of alkane: \(C_nH_{2n+2}\)
• The molecular formula and structural formula of the first ten member of alkanes is as shown below:

Molecular Formula

Structural Formula

• Increases as going down the group.

• As going down the group, the molecular size increases.
• Requires more energy to overcome the attractive forces.

• Increases as going down the group.

• As going down the group, the molecular size increases.
• Requires more energy to overcome the attractive forces.

• Increases as going down the group.

• As going down the group, the molecular size increases.

• Insoluble in water.

• Alkanes are covalent compounds.

• Does not conduct electricity.

• Does not contain freely moving ions.

•  Alkene: a group of organic compounds that are unsaturated hydrocarbons. 
• The general formula of alkene: \(C_nH_{2n}\)
• Homologous series: a group of organic compounds represented by a general formula, have the same functional group and every member is different from the others by a common structural unit, \(-CH_2\).
• Functional group: atom or group of atoms that determines the chemical properties of members of a homologous series.
• The molecular formula and structural formula of the first ten member of alkene is as stated below:

Number of Carbon Atoms

Molecular Formula

Structural Formula

• Increases as going down the group.

• As going down the group, the molecular size increases.
• Requires more energy to overcome the attractive forces.

• Increases as going down the group.

• As going down the group, the molecular size increases.
• Requires more energy to overcome the attractive forces.

• Increases as going down the group.

• As going down the group, the molecular size increases.

• Insoluble in water.

• Alkenes are covalent compounds.

• Does not conduct electricity.

• Does not contain freely moving ions.

•  Functional group: hydroxyl group, \(-OH\).
• General formula: \(C_nH_{2n+1}OH\).
• The structural formula and molecular formula of alcohol is as shown below:

• Replacing the ‘e’ at the end of the alkane name with ‘ol’.
• Example: methane to methanol.
• For a longer alcohol chain, the position of the hydroxyl group is mentioned in the name of the alcohol. 

1. Determine the name of the main chain based on the number of carbon atoms in the longest and continuous carbon chain.
2. The numbering of the main chain starts from the end closes to the hydroxyl group.
3. Determine the position of the hydroxyl group in the main carbon chain.
4. Determine the position of the branch chain.

• Remember, priority is given to the hydroxyl group first, then the branch chain.

Industry

Uses

• Solvents for paints, sticker, ink, lacquer and varnish.
• Used as fuel.

• Production of chemicals such as ethanoic acid and ester.

• Cosmetics, perfumes, toothpaste and skin lotions.

• To make medicines

• Functional group: carboxyl group, \(-COOH\).
• General formula: \(C_nH_{2n+1}COOH\).

• Replacing the ‘ol’ at the end of alcohol name with ‘oic acid’.
• Example: methanol to methanoic acid.

1. Determine the name of the main chain based on the number of carbon atoms in the longest and continuous carbon chain.
2. The numbering of the longest carbon chain starts from the carboxyl group.
3. Determine the position of the branch chain. 

• Fruits and vegetables contain carboxylic acid.
  • Orange has citric acid.
• Milk becomes sour because of the lactic acid formed.
• Used in daily life items:
  • Cosmetics.
  • Liquid detergent.
• Used in the food industry:
  • Food flavouring.
  • Food preservatives.

• In order to study the physical properties and chemical reactions of organic compounds, they are classified into groups of compounds called the homologous series..

• The same general formula..
• The same functional group.
• The same chemical properties.
• Consecutive members differ by one carbon atom and two hydrogen atoms (\(CH_2\) or relative molecular mass = 14).
• Physical properties that gradually change from one member to the next.
• The homologous series that will be learned in this topic is as shown below:
  • Alkane
  • Alkene
  • Alkyne
  • Alcohol
  • Carboxylic acid
  • Ester

• Alkane: a group of organic compounds that are saturated hydrocarbons. 
• A single carbon atom can form 4 bonds with other atoms.
• The general formula of alkane: \(C_nH_{2n+2}\)
• The molecular formula and structural formula of the first ten member of alkanes is as shown below:

Molecular Formula

Structural Formula

• Increases as going down the group.

• As going down the group, the molecular size increases.
• Requires more energy to overcome the attractive forces.

• Increases as going down the group.

• As going down the group, the molecular size increases.
• Requires more energy to overcome the attractive forces.

• Increases as going down the group.

• As going down the group, the molecular size increases.

• Insoluble in water.

• Alkanes are covalent compounds.

• Does not conduct electricity.

• Does not contain freely moving ions.

•  Alkene: a group of organic compounds that are unsaturated hydrocarbons. 
• The general formula of alkene: \(C_nH_{2n}\)
• Homologous series: a group of organic compounds represented by a general formula, have the same functional group and every member is different from the others by a common structural unit, \(-CH_2\).
• Functional group: atom or group of atoms that determines the chemical properties of members of a homologous series.
• The molecular formula and structural formula of the first ten member of alkene is as stated below:

Number of Carbon Atoms

Molecular Formula

Structural Formula

• Increases as going down the group.

• As going down the group, the molecular size increases.
• Requires more energy to overcome the attractive forces.

• Increases as going down the group.

• As going down the group, the molecular size increases.
• Requires more energy to overcome the attractive forces.

• Increases as going down the group.

• As going down the group, the molecular size increases.

• Insoluble in water.

• Alkenes are covalent compounds.

• Does not conduct electricity.

• Does not contain freely moving ions.

•  Functional group: hydroxyl group, \(-OH\).
• General formula: \(C_nH_{2n+1}OH\).
• The structural formula and molecular formula of alcohol is as shown below:

• Replacing the ‘e’ at the end of the alkane name with ‘ol’.
• Example: methane to methanol.
• For a longer alcohol chain, the position of the hydroxyl group is mentioned in the name of the alcohol. 

1. Determine the name of the main chain based on the number of carbon atoms in the longest and continuous carbon chain.
2. The numbering of the main chain starts from the end closes to the hydroxyl group.
3. Determine the position of the hydroxyl group in the main carbon chain.
4. Determine the position of the branch chain.

• Remember, priority is given to the hydroxyl group first, then the branch chain.

Industry

Uses

• Solvents for paints, sticker, ink, lacquer and varnish.
• Used as fuel.

• Production of chemicals such as ethanoic acid and ester.

• Cosmetics, perfumes, toothpaste and skin lotions.

• To make medicines

• Functional group: carboxyl group, \(-COOH\).
• General formula: \(C_nH_{2n+1}COOH\).

• Replacing the ‘ol’ at the end of alcohol name with ‘oic acid’.
• Example: methanol to methanoic acid.

1. Determine the name of the main chain based on the number of carbon atoms in the longest and continuous carbon chain.
2. The numbering of the longest carbon chain starts from the carboxyl group.
3. Determine the position of the branch chain. 

• Fruits and vegetables contain carboxylic acid.
  • Orange has citric acid.
• Milk becomes sour because of the lactic acid formed.
• Used in daily life items:
  • Cosmetics.
  • Liquid detergent.
• Used in the food industry:
  • Food flavouring.
  • Food preservatives.