"6N+2 Rule" for Writing Lewis Octet Structures

"6N+2 Rule" for Writing Lewis Octet Structures

 

 

The "6N+2 Rule" states that 6N+2 valence electrons are required to write an all-single-bonded, non-cyclic Lewis octet structure, where N is the number of non-hydrogen atoms in the molecule.

모두 단일 결합인 비고리형 루이스 구조에 필요한 원자가전자 수는 (6N+2)개이다. 여기서 N은 수소를 제외한 원자 수이다.

 

 

[Rules for Writing Lewis Octet Structures]

 

1) Calculate V, the total number of valence electrons in the molecule.

분자 내 각 원자의 원자가전자 수의 합을 V.

 

2) Calculate A, the number of valence electrons required for an all-single-bonded, non-cyclic Lewis octet structure, using the "6N+2 Rule".

(6N+2) 규칙을 사용하여 계산한 수를 A.

 

3) Calculate EB, the number of extra bonds, by subtracting the answer in step (1) from that in step (2) and dividing the resulting difference by 2: EB = (A – V) / 2.

(A – V) / 2 값을 EB.

 

For example, if A minus V is 4 electrons, then EB = 4/2 = 2, and there must be either 2 double bonds, or 1 triple bond, or 1 double bond and 1 ring, or 2 rings resent in any octet structure.

EB가 2이면, 이중 결합(d) 2개, 또는 삼중 결합(t) 1개, 또는 이중 결합 1개와 고리(r) 1개, 또는 고리 2개가 루이스 구조에 존재할 수 있다.

 

 

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[Sample]

 

(1) C2 H4 F

 

V = (2 × 4) + (5 × 1) + (1 × 7) = 20

A = ( 6 × 3 ) + 2 = 20

EB = (20 – 20) / 2 = 0

 

⇨ No multiple bonds or rings are present.

 

Acetic acid

 

 

 

(2) C O2

 

V = (1 × 4) + (2 × 6) = 16

A = ( 6 × 3 ) + 2 = 20

EB = (20 – 16) / 2 = 2

 

⇨ Possibilities: ① 2d; ② 1t; ③ 1d + 1r; ④ 2r

 

Carbon dioxide

 

 

 

(3) C2 H4 O2

 

V = (2 × 4) + (4 × 1) + (2 × 6) = 24

A = ( 6 × 4 ) + 2 = 26

EB = (26 – 24) / 2 = 1

 

⇨ Possibilities: ① Id; ② 1r

 

Acetic acid

  

  

1,3-Dioxetane (1,3-dioxacyclobutane)