Question

select the correct answer. which structure is the lewis structure for ammonia (nh₃)?
a.
$stackrel{..}{n}$—h—h—h

b.
h
|
h—n—h

c.
h
|
h—$stackrel{..}{n}$—h

d.
h—$stackrel{..}{n}$—h—h

Explanation:

To determine the Lewis structure of \( \text{NH}_3 \) (ammonia), we analyze the valence electrons: Nitrogen (\( \text{N} \)) has 5 valence electrons, and each Hydrogen (\( \text{H} \)) has 1, so total valence electrons are \( 5 + 3(1) = 8 \). Nitrogen forms three single bonds with Hydrogen atoms (using 6 electrons), leaving one lone pair (2 electrons) on Nitrogen.

• Option A: Shows single bonds between \( \text{N} \) and \( \text{H} \) atoms in a linear chain, but Lewis structures for \( \text{NH}_3 \) are trigonal pyramidal - like (with \( \text{N} \) as the central atom), and this structure does not show the lone pair on \( \text{N} \) correctly (also, the bonding is linear, not central - atom - based).
• Option B: The central \( \text{N} \) is bonded to three \( \text{H} \) atoms, but there is no lone pair on \( \text{N} \), which is incorrect as \( \text{N} \) should have one lone pair (since it uses 3 of its 5 valence electrons in bonding, leaving 2 as a lone pair).
• Option C: The central \( \text{N} \) is bonded to three \( \text{H} \) atoms, and there is a lone pair (two dots) on \( \text{N} \). This matches the valence electron distribution: 3 single bonds (6 electrons) and 1 lone pair (2 electrons), totaling 8 valence electrons.
• Option D: The lone pair is shown on the bond line, which is incorrect. Lone pairs should be associated with the central atom (Nitrogen) in the Lewis structure, not on the bond between \( \text{N} \) and \( \text{H} \).

Answer:

C. \(

$$\begin{matrix} & & \text{H} & & \\ & & | & & \\ \text{H} & - & \text{N} & - & \text{H} \\ & & \text{..} & & \end{matrix}$$

\)