Chapter 2, Problem 6CTQ

It is impossible to draw a legitimate Lewis structure of a neutral ${\text{NH}}_4$ molecule. Hypothetically,how many valence electrons would such a neutral ${\text{NH}}_4$ molecule have ifit could exist?
a. The +1 cation, ${\text{NH}}_4{}^{+}$ , does exist. How many valence electrons does one ${\text{NH}}_4{}^{+}$ ion have?
b. Draw the Lewis structure for ${\text{NH}}_4{}^{+}$