What is the chemical formula for the ammonium ion?

The ammonium ion has the chemical formula NH4+. This ion is formed when ammonia (NH3) accepts a proton (H+) and has a positive charge due to the addition of this proton. In NH4+, nitrogen is bonded to four hydrogen atoms, resulting in a molecular structure that is tetrahedral in shape. The presence of the additional hydrogen ion gives the ammonium ion a net positive charge, which is why it is represented as NH4+.

The molecular structure of the ammonium ion is important in various chemical reactions, especially in biological systems and in the formation of ammonium salts. Understanding the chemical nature of the ammonium ion is essential for comprehending its role in acid-base chemistry and its significance in various biochemical processes.

The other options do not correctly represent the ammonium ion. NH3+ suggests an incorrectly balanced charge and structure, while NH2- does not represent an ammonium species but rather an amide ion, which is negatively charged. NH4- would imply a negatively charged ammonium ion, which does not exist in stable form. Thus, NH4+ is the correct and recognized chemical formula for the ammonium ion.