National Chemistry

These notes are for the Scottish National Chemistry course taught in fourth year in most Scottish schools.

The notes available here are concise notes. They are NOT to be considered as material to learn from - they are for revision.

 The notes are arranged under the following topics

National 3 Unit 1
Unit 2
Unit 3

National 4 and 5 Unit 1 Rates of Reaction
Atomic Structure
Bonding and Properties
Acids and bases

National 4 and 5 Unit 2 Fuels and Homologous Series
Consumer Products
Carbohydrates

National 4 and 5 Unit 3 Metals
Plastics
Fertilisers
Nuclear Chemistry
Chemical analysis

.

National 4 and 5 Polymers

Polymers

1. Most plastics and synthetic (man-made) fibres are made from oil
  Properties - easy clean - hygienic; light; durable; electrical insulator; easily coloured; last a long tome (are not biodegardable)

Natural - expensive, wear out, but biodegradable and made from renewable sources
Man-made - made from finite resource (oil) - not biodegradable but cheap and long lasting.

Problems:
some plastics burn or smoulder giving off poisonous fumes.
not biodegradable

2 Thermosetting plastics cannot be reshaped by heating and melting - used for items which get hot - plugs, switches, electrical appliances. (They are set)
Thermoplastic plastics can be melted or reshaped.

3 Plastics are polymers - very large molecules made from a small molecule called a monomer-
 Many monomers are unsaturated hydrocarbons - aIkenes (with C=C) - produced by cracking longer chain aIkenes. Monomers form polymers by addition polymerisation.
Addition polymerisation

ethene produces polythene ;
  monomer polymer
  H H H H H H H H H H H H H

  C=C C=C C=C ------> -C-C- C- C-C-C-C -

  H H H H H H H H H H H H H

  ethene polythene

 Alkene monomers react by addition (breaking one of the bonds in the C=C) to polymerise

One bond of the double bond breaks open allowing each unsaturated monomer to make a
 connecting bond. (watch)
repeating unit

CONDENSATION POLYMERISATION
In this style of polymerisation the monomers join together and produce a water molecule. Polyesters are formed in this manner. The boxes represent a combination of atoms – this can vary quite widely. The atoms in the box are of no particular interest – just copy exactly if you need to.

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