How many electrons (both lone and bond pairs) are used in the Lewis structure of NH₃?

Question

Quizplus · Accepted Answer

To draw the Lewis structure of the molecule, we first need to calculate the total number of valence electrons.

N: 5 valence electrons 
H: 1 valence electron x 1 = 1 
S: 6 valence electrons 
B: 3 valence electrons x 2 = 6 
U: 6 valence electrons x 2 = 12 
Total: 5 + 1 + 6 + 12 = 24 valence electrons

Then, we can start by placing the atoms and bonding them by single bonds.

N-S-B-U-B-S

Each N, S, and B has an octet, except for N. N needs one more electron to complete its octet. We can then add a lone pair to N to satisfy the octet.

:N-S-B-U-B-S:

Each U has an expanded octet with 10 electrons around it (2 lone pairs and 2 bonding pairs).

Finally, we can count the total number of electrons used in the Lewis structure.

Bonding pairs: 7 x 2 = 14 
Lone pairs: 2 x 2 = 4 
Total: 14 + 4 = 18

However, we need to consider that in the question, it asks for both lone and bond pairs. This means that we need to count each bonding pair as 2 electrons (since there are 2 electrons in a single bond) and each lone pair as 2 electrons.

Bonding pairs: 14 x 2 = 28 
Lone pairs: 4 x 2 = 8 
Total: 28 + 8 = 36

Therefore, the answer is C) 8.

How Many Electrons (Both Lone and Bond Pairs) Are Used