Melting Point Mystery
What sets ionic compounds apart from covalent ones.
Setting up the bench…
What this lesson covers
Why it matters
A salt crystal won't conduct electricity — until you melt it. Ionic and covalent compounds behave like two different worlds.
Predict first
Why does solid salt conduct only after it melts?
Ionic compounds have high melting points and conduct when molten or dissolved (free ions). Covalent (molecular) compounds melt low and usually don't conduct (no ions).
- Melting frees its ions to move and carry charge — correct
- Heat turns the salt into a metal
- Salt gains electrons when heated
What you do
Sort each property into the right type of compound.
Check yourself
Ionic compounds have high melting points because…
Strong electrostatic forces throughout the lattice need a lot of energy to break.
Which of these conducts electricity?
Only molten or dissolved ionic compounds have free-moving ions to carry charge.
- strong forces hold the ions across a giant lattice — correct
- the ions are very heavy
- they contain metal atoms that melt slowly
- Molten sodium chloride — correct
- Solid sodium chloride
- Solid sugar