A student draws a dot-and-cross diagram for an oxygen molecule, O2\mathrm{O_{2}}O2. The diagram shows one shared pair of electrons between the atoms and three non-bonding pairs of electrons on each oxygen atom.
Why is this diagram incorrect?
Each oxygen atom would have only seven electrons in its outer shell
Each oxygen atom would have more than eight electrons in its outer shell
The oxygen atoms should transfer electrons to form O2+\mathrm{O^{2+}}O2+ and O2−\mathrm{O^{2-}}O2− ions
The diagram shows 14 outer electrons, but two oxygen atoms have only 12
53 exam-style questions on Edexcel GCSE Chemistry 2.4 Covalent bonding, covering 2.4.1 Covalent bonding and simple molecules. Each one has a worked solution and a mark scheme showing where the marks go.