Lesson Notes By Weeks and Term v4 - SHS 3
ORGANIC FUNCTIONAL GROUPS
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ORGANIC FUNCTIONAL GROUPS
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Subject: Chemistry
Class: SHS 3
Term: 2nd Term
Week: 20
Grade code: 3.2.2.LI.2
Strand code: 3
Sub-strand code: 2
Content standard code: 3.3.2.CS.2
Indicator code: 3.2.2.LI.2
Theme: CHEMISTRY OF CARBON COMPOUNDS
Subtheme: ORGANIC FUNCTIONAL GROUPS
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This lesson introduces the fascinating world of synthetic polymers, which are large molecules that form the basis of plastics, fibres, and many other materials we use every day. In Ghana, we are surrounded by polymers: the sachet for our "pure water," the "take-away" food containers, the nylon fishing nets used by our coastal communities, and the PVC pipes used in construction. While these materials are incredibly useful, their disposal creates significant environmental challenges, such as the clogging of our drains in Accra and other cities. This lesson will explore how these materials are made, why they are so useful, and how we can manage their impact on our environment.
2.1. Basic Definitions Monomer: A small, simple molecule that can be joined together in repeating units to form a polymer. Think of it as a single bead or a single paperclip. *Example:* Ethene (C₂H₄) is the monomer for poly(ethene). Polymer: A very large molecule (a macromolecule) made up of many repeating monomer units chemically bonded together. "Poly" means "many." Think of it as a long chain of beads or paperclips. *Example:* Poly(ethene), also known as polythene, is the polymer. Polymerisation: The chemical process in which monomers are joined together to form a polymer. 2.2. Types of Polymerisation
There are two main types of polymerisation you need to know: Addition and Condensation.
A. Addition Polymerisation
This type of polymerisation involves the joining of monomers without the loss of any atoms or molecules. The monomers are typically alkenes (or substituted alkenes) which have a carbon-carbon double bond (C=C). Mechanism: The double bond in the monomer breaks, and the electrons are used to form new single bonds with neighbouring monomer units, creating a long saturated chain. Key Feature: The empirical formula of the polymer is the same as that of the monomer.