A textbook represents magnesium oxide, MgO\mathrm{MgO}MgO, using a dot and cross diagram. The diagram shows one Mg2+\mathrm{Mg}^{2+}Mg2+ ion and one O2−\mathrm{O}^{2-}O2− ion, each in square brackets with its charge shown. The oxide ion has eight outer-shell electrons, including two transferred from magnesium.
Which statement identifies a limitation of this representation?
It leaves the charges of the magnesium and oxide ions unspecified.
It suggests that electrons are shared between magnesium and oxygen.
It shows the magnesium atom gaining two electrons from oxygen.
It represents only one pair of ions rather than the giant ionic lattice.
122 exam-style questions on OCR GCSE Chemistry 2.2 Bonding, covering 2.2.1 Metals, non-metals and the Periodic Table, 2.2.2 Types of chemical bonding and dot and cross diagrams, 2.2.3 Limitations of bonding models, and 2.2.4 Reactivity, atomic number and the modern Periodic Table. Each one has a worked solution and a mark scheme showing where the marks go.