HardChemistryHigh School (11–12)Chemical Bonding › Lewis Structures and Ionic BondsNumericalConceptual
Nitrous oxide, N₂O, has the atoms in the order N-N-O.
Contributed by StemPy LabTry it on paper first. A hint, the key idea and the worked solution are here when you need them.
Nitrous oxide, , has the atoms in the order N-N-O. Count its valence electrons. Find the formal charges in structure A, , and structure B, . Which structure is better?
Need a reminder? The key ideaShow
Lewis structure: count the valence electrons, adding one per negative charge and taking one per positive charge. Join the outer atoms to the central atom and complete their octets. Put the rest on the centre, and make multiple bonds if the centre is short. Formal charge: . Exceptions to the octet rule: incomplete octet, odd electrons, expanded octet.
The worked solution
Have you tried it?
Work it out on paper first. It is fine to get stuck or make a mistake: that is how we learn. When you are ready, go through the solution one step at a time, and check each step against your own.
Step 1. Count. electrons.
Step 2. Structure A, N=N=O. End nitrogen: . Central nitrogen: . Oxygen: .
Step 3. Structure B, N≡N-O. End nitrogen: . Central nitrogen: . Oxygen: .
Step 4. Compare. Both have charges of the same size. B puts the negative charge on oxygen, the more electronegative atom, so B is a little better. The real molecule is a mix of both.
Answer: 16 electrons; the central nitrogen is in both; B is preferred.
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