Name: resonance in nitrite and carbonate ions
Uploaded: 2025-05-22T09:05:33.000Z
Duration: 2 min 16 s
Channel: JoVE

대부분의 분자와 이온은 단일 루이스 구조로 표현됩니다. 그러나, 특정 화합물에서, 일부 전자는 특정 결합 또는 원자에 국한보다는 다중 결합 또는 원자를 통해 탈국된다. 이러한 화합물은 여러 루이스 구조로 정확하게 나타낼 수 있다.
황 삼산화화물에 대한 루이스 구조를 고려하십시오. 각 산소와 중앙 유황 원자 사이의 단일 결합은 산소 원자에 대한 옥텟을 만족시다. 그러나 유황에 대한 전체 옥텟에 도달하려면 유황과 산소 원자 중 하나 사이에 추가 결합이 형성되어야합니다.
황 삼산화물의 이러한 여러 루이스 구조는 공명 구조 또는 기여 구조라고합니다. 모든 구성 요소 원자의 공간 위치는 동일하게 유지됩니다. 그러나, 원자 전자는 다르게 분포된다.
이 이중 머리 화살표 쉼표로 생각할 수 있으며 평형에있는 공명 구조와 혼동해서는 안됩니다. 이러한 분자에서 실제 구조는 가중 평균 또는 공명 구조의 하이브리드입니다.
공명 구조는 '전자 밀기'에 의해 식별, 또는 채권으로 외로운 쌍을 변환하고 그 반대의 경우도 마찬가지, 곡선 화살표로 표시로. 이렇게 하면 분산된 영역을 매핑합니다.
이러한 탈지역화는 공명 안정화를 초래합니다- 즉, 이론적 비지역화 구조보다 더 낮은 잠재적 에너지를 가진 분자입니다.
기여 구조가 다른 것보다 에너지가 낮은 경우 실제 분자 구조와 더 가깝게 유사합니다. 특정 환경 설정은 다양한 기여 구조의 상대적 에너지를 추정하는 데 사용됩니다.
첫째, 모든 원자가 원자 껍질을 채우는 구조는 더 안정적입니다. 둘째, 더 많은 수의 공유 채권을 가진 구조는 더 안정적입니다. 셋째, 공식적인 요금을 최소화하는 구조는 더 안정적입니다.
마지막으로, 더 많은 전기 음성 원자에 음전하를 운반하는 구조와 덜 전기 음극에 대한 양전하가 더 안정적입니다.

공명 및 하이브리드 구조

Resonance and Hybrid Structures

공명 이론에 따르면, 동일한 원자 배열을 가진 두 개 이상의 루이스 구조가 분자, 이온 또는 라디칼에 대해 기술될 수 있는 경우 실제 전자 분포는 다양한 루이스 구조에서 나타나는 분포의 평균입니다.

공명 구조 및 공명 하이브리드

아질산염 음이온(NO2-)의 루이스 구조는 실제로 N–O 및 N=O 결합의 위치에 따라 구별되는 두 가지 다른 방식으로 그려질 수 있습니다.


<img alt="Figure1" src="/files/ftp_upload/11684/11684%20PT%20Figure%201.svg" style="text-align: center; height: 50px;">

아질산염 이온에 단일 결합과 이중 결합이 포함되어 있으면 두 결합 길이가 다를 것으로 예상됩니다. 두 원자 사이의 이중 결합은 동일한 두 원자 사이의 단일 결합보다 짧고 강합니다. 그러나 실험에 따르면 NO2-의 두 N-O 결합은 모두 동일한 강도와 길이를 가지며 다른 모든 특성도 동일합니다. 질소가 옥텟을 갖고 두 결합이 모두 동등한 NO2−에 대한 단일 루이스 구조를 쓰는 것은 불가능합니다.NO2-


대신, 공명 개념이 사용됩니다. NO2-의 각 질소-산소 결합에서 전자의 실제 분포는 이중 결합과 단일 결합의 평균입니다.

개별 루이스 구조를 공명 구조라고 합니다. 분자의 실제 전자 구조(공명 형태의 평균)를 개별 공명 형태의 공명 하이브리드라고 합니다. 루이스 구조 사이의 양방향 화살표는 이들이 공명 형태임을 나타냅니다.



<img alt="Figure2" src="/files/ftp_upload/11684/11684%20PT%20Figure%202.svg" style="text-align: center; height: 50px;">

탄산염 음이온인 CO3는 공명의 두 번째 예를 제공합니다.


<img alt="Figure3" src="/files/ftp_upload/11684/11684%20PT%20Figure%203.svg" style="text-align: center; height: 75px;">

<ul style="list-style-type: disc; display: flex; flex-direction: column; gap: 10px; padding: 0 0 0 40px;">
<li>중앙 원자의 옥텟을 완성하려면 산소 원자 하나가 탄소에 이중 결합을 가져야 합니다.
</li>
<li>그러나 모든 산소 원자는 동일하며 세 원자 중 어느 하나에서 이중 결합이 형성될 수 있습니다. 이는 탄산 이온의 세 가지 공명 형태를 발생시킵니다.
</li>
<li>동일한 공명구조 3개를 쓸 수 있으므로 탄산이온의 실제 전자배열은 3개 구조의 평균으로 알려져 있습니다.
</li>
<li>다시 실험을 통해 세 가지 C-O 결합이 모두 정확히 동일한 것으로 나타났습니다.
</li>
</ul>

공명 하이브리드로 설명되는 분자는 공명 형태로 설명되는 전자 구조를 결코 갖지 않습니다. 공명 형태 간에 변동되지 않습니다. 오히려 실제 전자 구조는 항상 모든 공명 형태로 나타나는 평균입니다.


이 문서는 에서 발췌되었습니다 <a href="https://openstax.org/books/chemistry-2e/pages/7-4-formal-charges-and-resonance">Openstax, Chemistry 2e, Chapter 7.4 Formal Charges and Resonance</a>.

공명 이론에 따르면, 동일한 원자 배열을 가진 두 개 이상의 루이스 구조가 분자, 이온 또는 라디칼에 대해 작성될 수 있다면 ...

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Organic Chemistry

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Unit 1

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Covalent Bonding and Structure

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주요 용어 및 개념

resonance in nitrite and carbonate ions

Resonance explains why some Lewis structures do not match the measured properties of a molecule or ion. When two or more Lewis structures have the same atom arrangement, the real electron distribution is an average of the structures shown.

The nitrite anion, NO2−, is one example. It can be drawn in two ways, with the N–O and N=O bonds in different places. If nitrite had one single bond and one double bond, the two bond lengths should be different, because a double bond is shorter and stronger than a single bond.

Experiments show that both N–O bonds in NO2− have the same length and strength. They are identical in all other properties as well. A single Lewis structure cannot show this and still give nitrogen an octet, so resonance is used to describe the ion.

The separate Lewis structures are called resonance structures. The true electronic structure is called a resonance hybrid, which is the average of the resonance forms. A double-headed arrow between Lewis structures shows that they are resonance forms. Nitrite does not switch back and forth between them. Its electron distribution is always the average of the forms.

The carbonate anion, CO3 2−, gives a second example. One oxygen must form a double bond to carbon to complete the octet on the central atom, but each oxygen atom is equivalent. That means the double bond can be placed with any one of the three oxygens, creating three resonance forms.

Because the three resonance structures are identical, the electron arrangement in carbonate is the average of all three. Experiments show that all three C–O bonds are exactly the same. A resonance hybrid never has the exact electronic structure of just one resonance form.

Resonance in Nitrite and Carbonate Ions

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Resonance explains why some Lewis structures do not match the measured properties of a molecule or ion. When two or more Lewis structures have the same atom arrangement, the real electron distribution is an average of the structures shown. The nitrite anion, NO2−, is one example. It can be drawn in two ways, with the N–O and N=O bonds in different places. If nitrite had one single bond and one double bond, the two bond lengths should be different, because a double bond is shorter and stronger...

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Explore how resonance explains equal bond lengths in nitrite and carbonate ions, and learn the difference between resonance structures and a resonance hybrid.

Resonance in Nitrite and Carbonate Ions | JoVE K12

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Resonance in Nitrite and Carbonate Ions

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