Final answer:
To draw a Lewis structure of ammonia, you should use 8 valence electrons. The nitrogen atom forms three covalent bonds with hydrogen, and the remaining two electrons form a lone pair on the nitrogen atom.
Step-by-step explanation:
Ammonia, which is represented as NH3, consists of one nitrogen atom and three hydrogen atoms. The central atom, nitrogen, has five valence electrons, while each hydrogen atom has one valence electron. To draw a Lewis structure for ammonia, we need to determine the number of valence electrons to be used.
The nitrogen atom contributes five valence electrons, while each hydrogen atom contributes one valence electron. Therefore, the total number of valence electrons is 5 (from nitrogen) + 3 (from hydrogen) = 8.
In the Lewis structure of ammonia, the nitrogen atom forms three covalent bonds with the three hydrogen atoms, using six of the eight valence electrons. The remaining two electrons form a lone pair on the nitrogen atom. The Lewis structure for ammonia is drawn by representing the nitrogen atom with three lines to represent the bonds with hydrogen atoms and placing two lone pairs around the nitrogen atom.