Organic molecules

Table of Contents

1. Organic molecules
2. Hydrocarbons
   1. Names and structures of hydrocarbons
3. Reactions of hydrocarbons
   1. Substitution reactions
   2. Addition reactions
4. Functional groups
   1. Identifying functional groups
5. Alcohols
   1. Structure of alcohols
   2. Physical properties of alcohols
6. Reactions of alcohols
   1. Oxidation reactions
   2. Carboxylic acids
   3. Alcohols, carboxylic acids and esters
   4. Identification of alcohols
7. Nitrogen in organic molecules
   1. Amines
   2. Amino acids
8. Determination of formulae and structures
   1. Empirical formulae
   2. Molecular mass and formula

1. Additional resources:
   1. Glossary
   2. Print content

Addition reactions

Substitution reactions can be a bit difficult to control because of the high energy involved and the possibility of a range of products, but addition reactions are far more easy to control and predict – they can occur at room temperature. For the reactions that are covered in this course, it is very easy to work out what the products will be. Writing balanced equations for these reactions should also be straightforward because there is only one product. The only thing you have to do is to add the reactants together to work out what the product is.

Substitution reactions occur when molecules, such as halogens (Cl₂, l₂ ,Br₂,F₂), hydrogen (H₂), hydrogen halides (HCl, HBr) and water (H₂O) react with alkenes. The double bond breaks and becomes a single bond. The reacting molecule splits, and one atom is added to each end of the 'old' double bond.

An example of an addition reaction is: propene + chlorine → 1,2-dichloropropane.

This reaction is shown in the video below.

Text alternative to the addition reaction video

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The equation for this reaction is shown below:

C₃H₆ + Cl₂ → CH₃CHClCH₂Cl. Note that in the equation the formula of the product is shown as a structural formula to show where the chlorine atoms have been added. You should try to do this when writing these equations yourself.

 

Complete the worksheet on Reactions of hydrocarbons .

The answers can be accessed here .