Final answer:
The incorrect statement about nucleophiles is that they are all negatively charged. Nucleophiles can be either neutral or negatively charged species that donate electrons to form bonds with electron-deficient atoms, often acting as Lewis bases.
Therefore the correct answer is option d. They are all negatively charged.
Step-by-step explanation:
Among the statements provided about nucleophiles, option d, 'They are all negatively charged,' is not correct. Nucleophiles can be neutral or anionic species that have the ability to donate a lone pair or bonding electrons to form a covalent bond. They are indeed Lewis bases, as they donate an electron pair (option a), and they do react with electrophiles at electron-deficient atoms (option b). The process involves nucleophiles donating an electron pair to the electrophile, leading to the formation of a new covalent bond (option c), which is also true. While most nucleophiles have an unshared electron pair that is donated to the electrophile (option e), they are not necessarily all negatively charged.
The distinction between a nucleophile and a base, although similar, pertains more to the type of reaction they participate in. While a base is generally involved in proton transfer reactions (acid-base reactions), a nucleophile is involved in reactions with electron-deficient atoms like carbon, which are not necessarily proton transfers. It's important to note that the reactivity of a nucleophile is not only about charge but also involves factors like steric hindrance and the solvent used.