Draw the Lewis structure for NO2F. Is this molecule polar? or nonpolar?
The correct answer and explanation is:
Correct Answer:
The Lewis structure for NO₂F (nitryl fluoride) has nitrogen in the center, double bonded to one oxygen, single bonded to another oxygen (which has a negative formal charge) and single bonded to a fluorine atom. The nitrogen atom carries a formal positive charge. The structure is drawn as:
O
||
N — O
\
F
The molecule is polar.
Explanation:
To draw the Lewis structure for NO₂F, first count the total valence electrons. Nitrogen has 5 valence electrons, each oxygen has 6 (total 12), and fluorine has 7. Adding them gives 24 valence electrons. Next, arrange nitrogen at the center since it is less electronegative than oxygen and fluorine. Connect the nitrogen atom to the two oxygen atoms and the fluorine atom with single bonds. This uses up 6 electrons (3 bonds × 2 electrons).
After placing lone pairs to satisfy the octet rule, it becomes clear that nitrogen does not reach a stable structure with only single bonds because it will lack a full octet. To fix this, a double bond is created between nitrogen and one oxygen atom. This results in one oxygen having two lone pairs, the other having three lone pairs and a negative charge, and nitrogen having a formal positive charge.
Regarding polarity, the molecule has an asymmetric shape due to the arrangement of the double bonded oxygen, single bonded oxygen and fluorine attached to the nitrogen. The oxygen and fluorine atoms are highly electronegative and pull electron density toward themselves. This unequal distribution of electron density leads to a net dipole moment. Because the molecule is not symmetrical, the individual bond dipoles do not cancel out.
Therefore, NO₂F is polar. Its polar nature affects its physical properties, like its boiling point and how it interacts with other substances. Its polarity allows it to dissolve in polar solvents and makes it reactive in various chemical reactions. Understanding its structure and polarity is essential for predicting its behavior in chemical processes.