1. If there are more than 2 elements, place the electron with the highest bonding capacity in the centre.
e.g. For the molecule NH3, nitrogen has a bonding capacity of 3, therefore it goes in the centre because hydrogen only has a bonding capacity of 1.
2. Complete single covalent bonds between the central and each terminal atom.
e.g. NH3 is created by using single bonds to make up the molecule.
3. Continue to form double and triple bonds until atom has reached a noble gas configuration.
e.g. Nitrogen has reached an octet and hydrogen only holds 2 electrons so there is no need to add double/triple bonds.
4. Determine molecular shape by considering the total number of electron pairs around central atom, and the number of lone pairs around central atom.
e.g. Nitrogen has 3 electron pairs with hydrogen and one lone pair. Therefore NH3 is a trigonal pyramidal (please look under the blogpost “Types of Shapes” for further explanation).
5. Although lone pairs influence the shape of the molecule only the atoms themselves make up the geometry of the atom.
e.g The lone pair repels the other electrons but are essentially “invisible” when drawing the diagram.
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