The table shows data for four halogens.
| Halogen | Boiling point (∘C^\circ\mathrm{C}∘C) | Energy needed to break the covalent bond in the molecule (kJ mol−1\mathrm{kJ\,mol^{-1}}kJmol−1) |
|---|---|---|
| F2\mathrm{F_{2}}F2 | -188 | 158 |
| Cl2\mathrm{Cl_{2}}Cl2 | -34 | 243 |
| Br2\mathrm{Br_{2}}Br2 | 59 | 193 |
| I2\mathrm{I_{2}}I2 | 184 | 151 |
Which conclusion is best supported by the data?
The boiling point of each halogen is set by the strength of its covalent bond
Iodine has the highest boiling point because its covalent bond is the strongest
Chlorine has the strongest bond, so its molecules attract each other most strongly
Boiling does not break covalent bonds; boiling point rises as molecules get larger
48 exam-style questions on Edexcel GCSE Chemistry 2.5 Types of substance, covering 2.5.1 Classifying substances by structure and bonding, 2.5.2 Properties of ionic and simple molecular substances, 2.5.3 Giant covalent structures: diamond and graphite, 2.5.4 Fullerenes, graphene and simple polymers, 2.5.5 Properties of metals and non-metals, and 2.5.6 Limitations of bonding models and representations. Each one has a worked solution and a mark scheme showing where the marks go.