Properties of ionic compounds
The of can be explained by their structure and .
Learn more on the properties of ionic compounds in this podcast.
Listen to the full series on BBC Sounds.
Melting points
Ionic compounds are held together by many strong forces between the oppositely charged . A lot of energy is needed to overcome these ionic bonds, so ionic compounds have high melting points.
| Ionic compound | Melting point |
| NaCl | 801°C |
| MgO | 2,852°C |
| Ionic compound | NaCl |
|---|---|
| Melting point | 801°C |
| Ionic compound | MgO |
|---|---|
| Melting point | 2,852°C |
Conduction of electricity
A substance can conduct electricity if:
- it contains , and
- these particles are free to move from place to place
Ionic compounds conduct electricity when (liquid) or in solution (dissolved in water), because their ions are free to move from place to place. Ionic compounds cannot conduct electricity when solid, as their ions are held in fixed positions and cannot move.
Solubility
Not all ionic substances are and some are more soluble than others.
When an ionic compound is added to water and it separates into its separate ions. The ions are surrounded by water .
Although a water molecule is neutral overall, it has a weak positive charge near its hydrogen atoms, and a weak negative charge near its oxygen atom. Water molecules surround the ions in solution because they are attracted by the charges of the ions.
