4:19 know the general formula for alkanes

Alkanes have the general formula CnH2n+2

This means that to work out the number of hydrogens, you double the number of carbons and then add two.

4:20 explain why alkanes are classified as saturated hydrocarbons


Saturated:   A molecule containing only single bonds between carbon atoms. For example, alkanes as described as saturated molecules.

Unsaturated:   A molecule containing a carbon-carbon double or triple bond. For example, alkenes as described as unsaturated molecules.


4:21 understand how to draw the structural and displayed formulae for alkanes with up to five carbon atoms in the molecule, and to name the unbranched-chain isomers

The displayed formulae show all the atoms and bonds drawn out.

The molecular formulae just show the number of each type of atom in the molecule.

4:22 describe the reactions of alkanes with halogens in the presence of ultraviolet radiation, limited to mono-substitution knowledge of reaction mechanisms is not required

Alkanes react with bromine in the presence of UV light, e.g. sunlight.

A hydrogen atom in the alkane is replaced by a bromine atom.

This is known as substitution.


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Section 1: Principles of chemistry

      a) States of matter

      b) Atoms

      c) Atomic structure

     d) Relative formula masses and molar volumes of gases

     e) Chemical formulae and chemical equations

     f) Ionic compounds

     g) Covalent substances

     h) Metallic crystals

     i) Electrolysis

 Section 2: Chemistry of the elements

     a) The Periodic Table

     b) Group 1 elements: lithium, sodium and potassium

     c) Group 7 elements: chlorine, bromine and iodine

     d) Oxygen and oxides

     e) Hydrogen and water

     f) Reactivity series

     g) Tests for ions and gases

Section 3: Organic chemistry

     a) Introduction

     b) Alkanes

     c) Alkenes

     d) Ethanol

Section 4: Physical chemistry

     a) Acids, alkalis and salts

     b) Energetics

     c) Rates of reaction

     d) Equilibria

Section 5: Chemistry in industry

     a) Extraction and uses of metals

     b) Crude oil

     c) Synthetic polymers

     d) The industrial manufacture of chemicals

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