Final answer:
A nucleophile is a type of species that donates electrons to an electron-deficient center to form a covalent bond. Nucleophiles are commonly seen in organic chemistry reactions, such as nucleophilic substitution reactions.
Step-by-step explanation:
A nucleophile is a type of species that acts as an electron donor by donating a lone pair or bonding electrons to form a covalent bond. In other words, it is a species that seeks an electron-deficient center to bond with. Nucleophiles are commonly seen in organic chemistry reactions, such as nucleophilic substitution reactions.
For example, in a nucleophilic substitution reaction, the nucleophile (Nu) replaces another nucleophile (X) on the substrate. This type of reaction involves an incoming nucleophile making a covalent bond with the electrophilic center, while the leaving group, which is a weaker nucleophile, departs.
In summary, a nucleophile is a species that donates electrons to an electron-deficient center, making it a sub-class of electrophiles. The reactivity of nucleophiles can vary, with good nucleophiles reacting faster in nucleophilic-electrophilic reactions.