Carbon has four outer-shell electrons and hydrogen has one electron. Methane has formula CH4\mathrm{CH_4}CH4.
Construct an outer-shell dot-and-cross diagram of methane. Use dots for carbon's electrons and crosses for hydrogen's electrons.
A student says that carbon forms methane by transferring one electron to each hydrogen atom. Use your diagram to explain why this is incorrect.
Explain why adding a fifth hydrogen atom with another shared pair would not match the usual complete-outer-shell model for carbon in methane.
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.