mothballs, dry ice, zinc, co2
Probably because it was first recognized in fluorspar or fluorite (which is calcium fluoride).
Fluoride(s) may be found in toothpaste and is even added in trace quantities to drinking water in certain parts of the world. Fluorine is extremely reactive and not found in nature. It may be found...
The bond is covalent. Two atoms of the same element will never form an ionic bond with each other.
Iodine and solid Carbon dioxide both sublimate directly to gases with no liquid phase.