The Lewis Dot Structure for NH4+

Created by MakeTheBrainHappy

The Lewis Dot Structure for NH4+ (Ammonium) is shown above. These kinds of structures can also be shown by representing each of the bonds with two dots. Each atom in the bond has a full valence shell, with nitrogen having access to eight electrons and each hydrogen having access to two (this is why hydrogen only needs two). The covalent bonds between the N and the H are similar to the ones formed between two Hs because the relatively small difference in electronegativity between carbon and hydrogen. The whole structure is a cation due to the fact that Nitrogen is missing an electron. Neutral Nitrogen atoms have five valence electrons which are a part of the original structure, while this central atom has four. Therefore it has a +1 charge.

Ammonium is a tetrahedron structure in 3D space similar to methane. Source

The positively charged cation allows ammonium to act as a weak acid and occasionally revert to its original form (NH3 = Ammonia). NH4+ takes up a tetrahedral shape (as shown above) due to the fact that there are no lone pairs on the central atom. It is an important source of nitrogen for certain types of plant species.

Source

Ammonium is known for forming different kinds of salts which would be classified as ionic compounds. In the image above, there are two salts shown which involve the ammonium ion. These are Ammonium carbonate and Ammonium sulphate. 

Sources:
https://pubchem.ncbi.nlm.nih.gov/compound/ammonium#section=Information-Sources