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### How to determine the relative contribution of resonance structures when different rules give contradictory outcomes?

In order to determine the relative contributions of resonance structures, my textbook gives the following rules (in order): The more covalent bonds a structure has, the higher it scores. Structures ...
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### Resonance structures and mechanism

I wrote the following resonance structures and our teacher wants us to write the curved arrows showing the mechanism as well... I was wondering if it's okay to show in which direction the mechanism ...
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### How does resonance fail in approximating chemical structures?

In the book "Concise Inorganic Chemistry" by Prof. JD Lee, it says here: These contributing structures do not actually exist. The $\ce{CO3^2-}$ does not consist of a mixture of these structures, ...
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### Why does coumarin predominantly exist in keto form?

By applying the logic that phenol exists in enol form rather than keto form as it attains aromatic character, why is it not the case in coumarin?
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### Which of the resonance structures is more stable?

I am quoting a rule on resonance from Organic Chemistry by T.W. Graham Solomons, Craig B. Fryhle, 12th edition, page 25. Structures in which all the atoms have a complete valence shell of ...
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### Stability and Resonance [duplicate]

The linked answers do attempt to clarify on 'stability' but I wanted an answer with specific connection to resonance. For example, the ethanoate ion can exist in many forms but, as we know from data,...
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### Which is most stable resonance structure of 4-nitrophenoxide ion?

According to my coaching module the first structure is more stable. Why is this so? I feel both must be approximately equally stable since negative charge is on oxygen in both cases. Would someone ...
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### Resonance structure and stability

Does the existence of resonance structures always translate as stability? I've been taught that resonance structures generally "spread out" charge in order to compensate for deficiency or excess of ...
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### Can a molecule be achiral whilst it's resonance form chiral?

I'm trying to work out whether methylphenylsulfoxide is a chiral molecule. It is my understanding that the sulfur uses sp2 hybridised orbitals. Why is this? The central sulfur atom is bound to 3 ...
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### What is the most “important” resonance structure of SCN⁻?

Numerous online references say that $\ce{SCN-}$ has two resonance structures: I am wondering why this structure is not also possible? I expect structure 3 to be rare because of the high formal ...
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### VSEPR theory, chemical bond and quantum mechanics

VSEPR theory correctly predicts the shapes of many symmetry-broken molecules such as $\ce{H2O}$ and $\ce{NH3}$. Take $\ce{NH3}$ for example. In VSEPR theory, the nitrogen atom is (approximately) at ...
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### Mechanism of Biosynthesis of Terpenes

There is a specific part of the biosynthesis of terpenes that makes me confused: According to this mechanism, the double bond of the isopentenyl pyrophosphate attacks the primary carbocation, when it ...
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### Where do the lone pairs go in the “true” resonance structure?

Consider the "true" resonance structure of $\ce{CO3^2-}$: The bottom diagram leaves out the 2 lone pairs, so 4 electrons disappeared in the bottom image as compared to the top one. Are these ...
A question on the 1996 AP Chemistry Free Response asks: The $\ce{N-O}$ bonds in the $\ce{NO2-}$ ion are equal in length, whereas they are unequal in $\ce{HNO2}$. Explain. Since the nitrogen ...