An oxide contains sodium ions and oxide ions. Sodium atoms have electronic configuration 2,8,1 2,8,1\,2,8,1 and oxygen atoms have electronic configuration 2,62,62,6.
Draw a dot-and-cross diagram showing the correct smallest whole-number ratio of ions in this oxide. Use dots for oxygen's original outer-shell electrons and crosses for transferred sodium electrons. Show the oxide ion's outer shell and brackets and charges for all ions. Sodium ions may be represented without electron shells.
Deduce the formula of the oxide and explain why one sodium atom cannot supply all the electrons needed by one oxygen atom.
A student erases the ion charges but leaves the electron symbols unchanged. Explain why the resulting diagram no longer fully represents the bonding.
56 exam-style questions on Edexcel GCSE Chemistry 2.3 Ionic bonding, covering 2.3.1 Ions and the formation of ionic bonds, 2.3.2 Naming and deducing formulae of ionic compounds, and 2.3.3 Giant ionic lattices. Each one has a worked solution and a mark scheme showing where the marks go.