Final answer:
The Lewis structure with H-N-H notation has four electron groups, comprising three bonding pairs (the bonds with hydrogen atoms) and one lone pair on the nitrogen atom, resulting in three bonding domains.
Step-by-step explanation:
The Lewis structure in question involves a nitrogen atom with two hydrogen atoms attached to it, as indicated by the H-N-H notation. According to the description, the nitrogen atom has four electron groups around it. This includes three bonding pairs and one lone pair. The three bonding pairs correspond to the single bonds that nitrogen forms with each hydrogen atom. The remaining lone pair consists of two electrons that are not shared with any other atom, existing as a lone pair on the nitrogen atom.
In summary, nitrogen forms three bonds with hydrogen atoms, creating a shape similar to a tetrahedron with one vertex occupied by the lone pair. This arrangement minimizes electron-electron repulsions between the electron groups around the nitrogen atom, following the VSEPR theory. Thus, the Lewis structure H-N-H indicated in the question has three bonding domains.