Explain what is meant by the term covalent bonding.
Describe or draw a dot-and-cross diagram to show the bonding in a molecule of carbon dioxide, CO2\text{CO}_2CO2. Show only the outer electrons.
Substances P and Q are covalently bonded and have simple molecular structures. The table below gives the boiling points for substances P and Q.
| Substance | Boiling point in ∘C^\circ\text{C}∘C |
|---|---|
| P | -162 |
| Q | -89 |
Explain why substances with simple molecular structures have low boiling points.
Suggest why the boiling point of Q is higher than the boiling point of P.
Substance Q has the empirical formula CH3\text{CH}_3CH3 and an MrM_rMr value of 30. Determine the molecular formula of substance Q.
Substance Y is also covalently bonded, but its structure is different from that of P and Q. It has a boiling point of 3550 ∘C3550\ ^\circ\text{C}3550 ∘C.
Explain, in terms of its structure, why Y has such a high boiling point.
15 exam-style questions on Edexcel IGCSE Chemistry Covalent bonding. Each one has a worked solution and a mark scheme showing where the marks go.