A covalent bond is between two nonmetals. An ionic bond is between a metal and a nonmetal. Potassium is a metal and iodine is a nonmetal, so their bond would most likely be ionic.
Light travels in waves AND in bundles called "photons".
It's hard to imagine something that's a wave and also a bundle.
But it turns out that light behaves like both waves and bundles.
If you design an experiment to detect waves, then it responds to light.
And if you design an experiment to detect 'bundles' or particles, then
that one also responds to light.
