Can a single atom be considered a molecule?

no

Explanation:

Molecules are distinguished from ions by their lack of electrical charge. ... Atoms and complexes connected by non-covalent interactions, such as hydrogen bonds or ionic bonds, are typically not considered single molecules. Molecules as components of matter are common in organic substances (and therefore biochemistry).

A molecule is a single unit created by two or more atoms that are tightly bonded together. Diatomic molecules are molecules which are made of two atoms. Certain elements are diatomic elements because they do not naturally occur as single atoms, but as a pair of atoms
So the answer is NO

Iodine is not very soluble in water, therefore the iodine reagent is made by dissolving iodine in water in the presence of potassium iodide.

Explanation:

This makes a linear tri-iodide ion complex with is soluble that slips into the coil of the starch causing an intense blue-black colour