The following links offer some useful revision to support your learning:
BBC Bitesize – Chemical Formulae
West OS – Writing Formula for Covalent Molecular Compounds
West OS – Writing Ionic Formulae Part 1
West OS – Writing Ionic Formulae Part 2 (Group Ions)
Miss Adams – Chemical Formulae – Prefix Names
Miss Adams – Chemical Formulae – Cross Over Method
Miss Adams – Chemical Fomulae – Valency Method
Miss Adams – Chemical Formulae – Writing Ionic Formulae
To help with your learning, you may also wish to try some of the following resources:
Game: Balancing Chemical Equations
Within the National 5 Chemistry course, you will need to know:
Chemical formulae
- Compound names are derived from the names of the elements from which they are formed.
- Most compounds with a name ending in ‘-ide’ contain the two elements indicated.
- The ending ‘-ite’ or ‘-ate’ indicates that oxygen is also present.
- Chemical formulae can be written for two element compounds using valency rules and a Periodic Table.
- Roman numerals can be used, in the name of a compound, to indicate the valency of an element.
- The chemical formula can also be determined from names with prefixes.
- The chemical formula of a covalent molecular substance gives the number of each type of atom present in a molecule.
- The formula of a covalent network gives the simplest ratio of each type of atom in the substance.
- Ions containing more than one type of atom are often referred to as group ions.
- Chemical formulae can be written for compounds containing group ions using valency rules and the data booklet.
- Ionic formulae give the simplest ratio of each type of ion in the substance and can show the charges on each ion, if required.
- In formulae, charges must be superscript and numbers of atoms/ions must be subscript.
