Current Flow: Electrons vs Ions
Electrons or ions — how different things carry current.
Setting up the bench…
What this lesson covers
Why it matters
A copper wire and a beaker of brine both light a bulb — but they move charge in completely different ways.
Predict first
How does molten sodium chloride carry an electric current?
Metals and graphite conduct by free electrons. Electrolytes (molten or dissolved ionic compounds and acids) conduct by free-moving ions. Substances with no free ions or electrons don't conduct.
- By moving ions — correct
- By moving electrons, like a metal
- It cannot carry current at all
What you do
Sort each one by how (or whether) it conducts electricity.
Check yourself
An electrolyte conducts electricity because it has…
Electrolytes carry charge through mobile ions, not electrons.
Why doesn't solid NaCl conduct?
The ions exist but are fixed in place until the salt is melted or dissolved.
- free-moving ions — correct
- free electrons
- no charged particles
- Its ions are locked in the lattice and can't move — correct
- It contains no ions
- It has too many electrons