Final answer:
The iodide ion, I-, is characterized as a nucleophile due to its negative charge and ability to donate a lone pair of electrons to form new covalent bonds.
Step-by-step explanation:
The iodide ion, I-, characterized in terms of chemical reactivity, would be considered a nucleophile. This is because an iodide ion has an extra electron, giving it a negative charge and a complete valence shell with lone pairs of electrons that it can donate to form a new covalent bond. In organic and bioorganic transformations, electrophiles are generally electron-deficient species that accept electron pairs, whereas nucleophiles are the species that donate electron pairs.
So, in the case of an iodide ion, I-, it has more electrons than protons and thus carries a negative charge. This makes it very willing to share its lone pair of electrons with an electrophilic center, such as in the substitution reactions where it often acts as a very good leaving group.