Carbon Compound

  1. Carbon is located in group 14. A carbon atom contain 6 electrons, therefore the electronic configuration is 2.4.
  2. It has 4 valance electrons in the outermost orbital, as shown in the diagram.
  3. In order to achieve a stable outer octet of electrons, it forms four covalent bonds. 


Example

Methane


When a carbon atom combines with four hydrogen atoms, it forms a molecule of methane, CH4

Ethane


If two carbon atoms join, each can still combine with three hydrogen atoms to form a molecule of ethane, C2H6.

Number of Bonds

Each carbon atom is tied to other atoms through four covalent bonds. All the four covalent bonds may exist in three forms as shown below:
 Possesses just single bond  Possesses a double bond  Possesses a triple bond

Carbon Compounds

Carbon compounds can be divided to:
  1. Organic carbon compounds 
  2. Inorganic carbon compounds




Hydrocarbon

MUST Remember!
Hydrocarbons are organic compounds that contain only carbon and hydrogen.
Saturated Hydrocarbon
Saturated Hydrocarbon
    1. Hydrocarbon is a compound made out of the elements carbon and hydrogen only.
    2. Examples of hydrocarbon are alkane, alkene and alkyne. 
    3. Hydrocarbon can be divided into two groups:
      1. saturated hydrocarbon
      2. Saturated hydrocarbons are hydrocarbons where all its carbon atoms are tied to each other through single covalent bond only. Examples: alkanes
      3. unsaturated hydrocarbon
      4. Unsaturated hydrocarbons are hydrocarbons which contains at least one double covalent bond among its carbon atoms. Examples: alkenes
Unsaturated Hydrocarbon
  1. Ethanol ( C2H5OH ), ethanoic acid (CH3COOH), metal methanoat (HCOOCH3), chloromethane (CH3Cl) and others are not hydrocarbons because the molecule contains other elements such as chlorine or oxygen other than carbon and hydrogen.
MUST Know!
  • Saturated – All single bond between carbons 
  • Unsaturate – Has at least one double/triple bond between carbons

Comparing Saturated and Unsaturated Hydrocarbon

Saturated Hydrocarbon Unsaturated Hydrocarbon
Combustion Produce less soot Produce more soot
Reaction with bromine water The brown colour of bromine remain unchanged Decoloarise the brown colour of bromine
Reaction with potassium manganate(VII) solution The purple colour of potassium manganate (VII) solution remain unchanged Decolourise the purple colour of potassium manganate (VII) solution

Sources of Hydrocarbon:

The main sources of hydrocarbons are
  1. Coal
  2. Natural gas
  3. Petroleum

Combustion of Hydrocarbon

All hydrocarbons undergo combustion with oxygen to produce carbon dioxide (or carbon monoxide/carbon) and water. There are 2 types of combustion:
  1. Complete combustion – organic compounds burn completely which form CO2 and H2O
  2. Incomplete combustion– organic compounds burn with limited supply of O2 which form C (soot), CO, CO2 and H2O.

Example

Complete combustion

C2H6 + 7/2 O2 → 2CO2 + 3H2O

C3H6 + 9/2 O2 → 3CO2 + 3H2O

Incomplete combustion

C2H6 + 5/2 O2 → 2CO + 3H2O

C2H6 + 3/2 O2 → 2C + 3H2O


C3H6 + 3O2 → 3CO + 3H2O

C3H6 + 3/2 O2 → 3C + 3H2O

Note:

  1. The soot from the combustion of a hydrocarbon depends on the percentage of carbon it contains.
  2. Higher carbon percentage in the hydrocarbon molecule will result sootier flame.

Homologous Series

    1. A series of compounds with similar chemical properties, in which members differ from one another by the possession of an additional CH2 group, is called a homologous series. 
    2. Each homologous series must have the following four characteristics:
      1. Every member in the homologous series can be represented by a common formula. For example: 
        1. Alkane: CnH2n+2
        2. Alkene: CnH2n
        3. Alcohol: CnH2n+1OH
        4. Carboxylic acid : CnH2n+1COOH
        5. Ester: CnH2n+1COOCmH2m+1
      2. Every member differ from others by the group -CH2– which has the relative mass 14. For example:
      1. Members of the same homologous series can be prepared through one common method. For examples, All alkenes can be prepared by dehydration of relevant alcohols.

Preparing Ethene (Dehydration of ethanol):

C2H5OH → C2H4 + H2O

Preparing Propene (Dehydration of propanol)

C3H7OH → C3H8 + H2O

    1. Members of the homologous series have the same chemical properties. For example:All alkenes show addition reaction as added into bromine.

Functional Group

Functional group is a group of atoms tied together which will take part in a chemical reaction therefore determine the chemical properties of the series.
  1. Members of the same homologous series have the same chemical properties because of the presence of a common functional group in all the molecules of the series.
  2. Functional group is a group of atoms tied together which will take part in a chemical reaction therefore determine the chemical properties of the series.
  3. Therefore, the homologous series is a family of organic compound that is made out of members with common functional group, common chemical properties, and consecutive members are differ by one carbon atom and two hydrogen atom, namely, –CH2-.
  4. Table below shows some homologous series and their respective general formula and functional group.

Carbon Compounds General Formula Functional group
Alkane CnH2n+2 Carbon-carbon single bond
– C – C –
Alkene CnH2n Carbon-carbon double bond
– C = C –
Alcohol CnH2n+1OH Hydroxyl group
– OH
Carboxylic Acids CnH2n+1COOH Carboxyl group
– COOH
Esters CnH2n+1COOCmH2m+1 Carboxylate group
– COO –