Properties of Ionic Compounds - Structure & Bond
Chemistry: Cambridge International GCSE Supplement, topic 2.4.1
Properties of Ionic Compounds: Structure and Bonding
Ionic compounds form strong crystal lattices and have high melting points due to strong bonds. They conduct electricity only when molten or dissolved in water.
Ionic compounds structure
- Ionic compounds form a giant lattice of positive and negative ions.
- Opposite charges attract, creating strong ionic bonds.
- The ions arrange regularly in a 3D pattern.
- This structure is very stable and affects the compound's properties.
High melting and boiling points
- Ions in ionic compounds attract strongly.
- Ionic bonds require a lot of heat energy to break.
- This results in high melting points and boiling points.
- Example: Sodium chloride melts at 801°C.
Electrical conductivity in solid state
- In solid ionic compounds, ions cannot move freely.
- Ions are locked in place in the lattice.
- Solid ionic compounds do not conduct electricity.
Electrical conductivity when molten or aqueous
- Ionic compounds conduct electricity when molten or dissolved.
- Heat melts the lattice, freeing the ions.
- Water breaks the lattice apart, allowing ions to move.
- Free ions carry electric current effectively.
Summary of properties and reasons
- Ionic compounds have high melting and boiling points due to strong ionic bonds.
- They do not conduct electricity when solid because ions are fixed.
- They conduct electricity when molten or dissolved because ions move freely.
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