# How can I determine if and when a molecule has or needs a resonance structure?

A molecule can have resonance structures when it has a lone pair or a double bond on the atom next to a double bond.

Whenever you can draw two or more Lewis structures for a molecule, differing only in the locations of the electrons, the actual structure is none of the structures but is a hybrid of them all.

For example, what is the Lewis structure of the nitrite ion, NO₂⁻?

1. Decide which is the central atom in the structure. That will normally be the least electronegative atom (N).

2. Draw a skeleton structure in which the other atoms are single-bonded to the central atom: O-N-O.

3. Draw a trial structure by putting electron pairs around every atom until each gets an octet. In this editor, I will have to write it as ::Ö-N(::)-Ö::

4. Count the in your trial structure (20).

5. Now count the you actually have available.

1 N + 2 O + 1 = 1×7 + 2×6 +1 = 18.

The trial structure has two more electrons than are available.

6. Draw a new trial structure, this time inserting one double bond for each extra pair of electrons: O-N=O and O=N-O (two possibilities) — Right here, the two possibilities tell us that that we will have two resonance structures.

7. As before, add valence electrons to give each atom an octet:

8. Assign formal charges to each atom.

Each atom “owns” its lone pair electrons and half of the shared pairs.

The right hand O atom has 6 lone pair electrons plus 1 from the single bond. This is one more electron than in an isolated O atom. So the formal charge on O is -1.

The two resonance structures are:

The actual structure is none of these. It is a resonance hybrid of them both.

Show more

## Calculate the price of your order

550 words
We'll send you the first draft for approval by September 11, 2018 at 10:52 AM
Total price:
\$26
The price is based on these factors:
Academic level
Number of pages
Urgency
Basic features
• Free title page and bibliography
• Unlimited revisions
• Plagiarism-free guarantee
• Money-back guarantee
• 24/7 support
On-demand options
• Writer’s samples
• Part-by-part delivery
• Overnight delivery
• Copies of used sources
• Expert Proofreading
Paper format
• 275 words per page
• 12 pt Arial/Times New Roman
• Double line spacing
• Any citation style (APA, MLA, Chicago/Turabian, Harvard)

# Our guarantees

Delivering a high-quality product at a reasonable price is not enough anymore.
That’s why we have developed 5 beneficial guarantees that will make your experience with our service enjoyable, easy, and safe.

### Money-back guarantee

You have to be 100% sure of the quality of your product to give a money-back guarantee. This describes us perfectly. Make sure that this guarantee is totally transparent.

### Zero-plagiarism guarantee

Each paper is composed from scratch, according to your instructions. It is then checked by our plagiarism-detection software. There is no gap where plagiarism could squeeze in.

### Free-revision policy

Thanks to our free revisions, there is no way for you to be unsatisfied. We will work on your paper until you are completely happy with the result.

### Privacy policy

Your email is safe, as we store it according to international data protection rules. Your bank details are secure, as we use only reliable payment systems.

### Fair-cooperation guarantee

By sending us your money, you buy the service we provide. Check out our terms and conditions if you prefer business talks to be laid out in official language.

Order your essay today and save 10% with the coupon code: best10