Which of the following is the correct Lewis structure for nitrogen gas, [tex]$N _2$[/tex]?
Answer (2)
Determine the number of valence electrons for each nitrogen atom: 5.
Calculate the total number of valence electrons for the N 2 molecule: 2 × 5 = 10 .
Draw the Lewis structure for N 2 such that each nitrogen atom has an octet of electrons: :N ≡ N:
Compare the drawn Lewis structure with the provided Lewis structure : N ≡ N : and conclude that it is correct.
Explanation
Problem Analysis We are asked to determine if the given Lewis structure for nitrogen gas ( N 2 ) is correct. The Lewis structure provided is : N ≡ N :
Valence Electrons of Nitrogen First, we need to determine the number of valence electrons for a nitrogen atom. Nitrogen is in group 15 (or 5A) of the periodic table, so it has 5 valence electrons.
Total Valence Electrons Since there are two nitrogen atoms in N 2 , the total number of valence electrons in the molecule is 2 × 5 = 10 valence electrons.
Drawing the Lewis Structure Now, let's draw the Lewis structure for N 2 . We start by drawing the two nitrogen atoms and placing a single bond between them: N-N. This uses 2 valence electrons, leaving 10 − 2 = 8 electrons to distribute. We can distribute these remaining electrons as lone pairs around the nitrogen atoms. To satisfy the octet rule for each nitrogen atom, we need to have 8 electrons around each N. So, we can try placing three bonds between the two N atoms, which means N ≡ N. This uses 3 × 2 = 6 electrons in the bonds. Then, we add one lone pair to each nitrogen atom. This adds 2 × 2 = 4 electrons. The total number of electrons used is 6 + 4 = 10 , which is the total number of valence electrons we calculated earlier. Therefore, the Lewis structure is :N ≡ N:
Conclusion Comparing the Lewis structure we derived (:N ≡ N:) with the provided Lewis structure (: N ≡ N :), we see that they are the same. Thus, the provided Lewis structure is correct.
Examples
Lewis structures are used to visualize the bonding between atoms in a molecule, which helps in predicting molecular properties like polarity and reactivity. For example, understanding the Lewis structure of C O 2 helps explain why it is a nonpolar molecule despite having polar bonds. In the case of nitrogen gas, its triple bond makes it relatively inert and unreactive, which is why it is used as a protective atmosphere in many industrial processes. Knowing the Lewis structure helps us understand why nitrogen is so stable and unreactive.
The correct Lewis structure for nitrogen gas ( N 2 ) is :N≡N:. Each nitrogen atom shares three pairs of electrons to satisfy the octet rule, totaling ten valence electrons. This structure indicates a strong triple bond between the two nitrogen atoms, confirming its stability.
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