1      The potassium atom shares a pair of electrons with the fluorine atom to form a simple molecule.

2      After donating its valence electron to the fluorine atom, the potassium ion forms a molecule with the fluoride ion.

3      Potassium fluoride exists as a lattice (giant structure) consisting of potassium ions and fluoride ions.

4      Potassium fluoride exists as a lattice consisting of covalently bonded potassium and fluorine atoms.