The best prompt to begin such a construction is a Kekulé
representation of the molecule; able students can build quite
complex molecules using this modeling technique from such
representations. When students are familiar in the method of
constructing the models, they are able to build the models bond
by bond, dealing with each electron pair in turn. Figure 4 shows
the construction of a model of sulfuric acid using this method;
the sulfur has 12 electrons in its valence shell. In this
construction students largely ignore the number of valence
electrons in each shell until they come to evaluate the model at
the end of its construction. This leads to a “lightbulb” moment where they realize that not all the atoms have 8 electrons in
their outer shell. This is a useful prompt to extend students’
understanding of bonding theory and the usefulness of the
octet rule. Teachers can then choose whether to probe this idea
further or simply sow the seed for further learning, depending
on the constraints of their curriculum.