How does NH4+ come to being?

There are 5 valence electrons in Nitrogen and in order for it to have a complete outer shell (8 electrons) it needs 3 more electrons. Why is it the case that the Nitrogen needs 4 Hydrogen instead of 3 Hydrogen?


(What is the full name of $\ce{NH4+}$ other than Ammonium?)




Check this picture. Nitrogen has 5 electrons, as you've said: in ammonia, 3 for covalent bonds and 2 as electron pair (dots on picture). That's why ammonia is a base (check for Brønsted–Lowry theory). And bases are capable of donating electron pair - thus, accepting proton. Ammonia then becomes its conjugate acid - ammonium.


[![enter image description here](https://i.stack.imgur.com/JzgLf.png)](https://i.stack.imgur.com/JzgLf.png)


p.s. It's common IUPAC name is azanium.
<http://old.iupac.org/publications/books/rbook/Red_Book_2005.pdf>


 3