Cambridge IGCSE Chemistry · Syllabus 0620 · Atoms, Elements and Compounds
Mobile ions
What is Mobile ions?
Charged particles that are free to move through a substance and so can carry an electric current. An ionic compound contains ions in every state, but they are locked in fixed positions in the solid lattice; melting or dissolving breaks the lattice apart and allows the ions to move, which is why an ionic compound conducts only when molten or in aqueous solution. The charge carriers in these cases are ions, never electrons.
This definition is part of the Atoms, Elements and Compounds chapter in Cambridge IGCSE Chemistry.