Both nitrogen (N) and chlorine (Cl) have electronegativity of 3.0. However, only nitrogen is involved in the hydrogen bonds (e.g., `NH_(3)`) and not chlorine. This is an account of smaller atomic size of nitrogen (atomic radius =70 ppm) as compared to chlorine (atomic radius =99 pm). Therefore, N can cause greater polarisation of N-H bond than Cl in case of Cl-H bond. Consequently, N atom is involved in hydrogen bonding and not chlorine.
