NH2 is a nucleophile.

Nucleophiles are species that have a lone pair of electrons and are capable of donating these electrons to form a new bond. They are attracted to positively charged atoms or molecules, known as electrophiles. On the other hand, electrophiles are species that can accept a pair of electrons and are attracted to nucleophiles.

1. Definition of Nucleophile:
A nucleophile is a species that donates a pair of electrons to form a new bond. It is characterized by the presence of a lone pair of electrons on an atom or a group of atoms. This lone pair of electrons can be used to form a bond with an electrophile.

2. Structure of NH2:
NH2 refers to an amino group (-NH2) attached to a molecule. In this case, we consider NH2 as a nucleophile due to the presence of a lone pair of electrons on the nitrogen atom. Nitrogen has five valence electrons, and in NH2, it forms three sigma bonds with hydrogen atoms, leaving one lone pair of electrons.

3. Electron Donating Ability:
The lone pair of electrons on the nitrogen atom in NH2 makes it a strong nucleophile. This lone pair is available to donate and form a new bond with an electrophile. The lone pair can be used to attack electrophilic centers, such as positively charged atoms or molecules, to initiate a chemical reaction.

4. Reactivity of NH2:
NH2 can participate in various nucleophilic reactions. For example, it can react with electrophiles such as alkyl halides, forming a new bond between the nitrogen atom and the electrophilic carbon atom. This type of reaction is known as nucleophilic substitution. NH2 can also react with carbonyl compounds, such as aldehydes or ketones, to form imines or enamines, respectively.

5. Examples of Nucleophilic Reactions:
NH2 can act as a nucleophile in reactions such as nucleophilic substitution, nucleophilic addition, and nucleophilic acyl substitution. In all these reactions, NH2 donates its lone pair of electrons to an electrophile, resulting in the formation of a new bond.

In conclusion, NH2 is considered a nucleophile due to the presence of a lone pair of electrons on the nitrogen atom. This allows it to donate electrons and form new bonds with electrophiles in various nucleophilic reactions.

It is a nucleophile..