Lewis Dot

**Lewis** **Dot**

Rule 3: Too many electrons

©copyright by James B. Condon (2013) all rights reserved.

©Some of the graphics are supplied by Corel Corporation with their permission.

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altered. Donations to the Roane State Foundations would be appreciated in

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Index:

A Rule 3 - Too many e – s

2–

B Example 1 - SF 4

C Example 2 - PF 5

–

D Example 3 - I 3

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1

**Lewis** **Dot** Rule 3: Too many electrons for the

rule of 8 (2) to accommodate them.

Rule 4: Elements in periods (rows) 3 and greater

can accommodate 10 and 12 electrons if they are

not terminal atoms.

2

**Lewis** **Dot** Rule 3: Too many electrons for the

rule of 8 (2) to accommodate them.

Rule 4: Elements in periods (rows) 3 and greater

can accommodate 10 and 12 electrons if they are

not terminal atoms.

Example 1: What is the **Lewis** **Dot** structure for

SF 2– ion?

3

**Lewis** **Dot** Rule 3: Too many electrons for the

rule of 8 (2) to accommodate them.

Rule 4: Elements in periods (rows) 3 and greater

can accommodate 10 and 12 electrons if they are

not terminal atoms.

Example 1: What is the **Lewis** **Dot** structure for

SF 2– ion?

""

F

!!

= charge

" "

initially:

"

S = 6

""

! ""

F" S

" F

4×F = 4×7 " ! ! " ! "

"

charge = 2

"

total = 36

" F ""

"

""

4

**Lewis** **Dot** Rule 3: Too many electrons for the

rule of 8 (2) to accommodate them.

Rule 4: Elements in periods (rows) 3 and greater

can accommodate 10 and 12 electrons if they are

not terminal atoms.

Example 1: What is the **Lewis** **Dot** structure for

SF 2– ion?

""

F

!!

= charge

" "

initially:

"

S = 6

""

! ""

4×F = 4×7

F" S

"

! ! F

" " ! "

"

charge = 2

"

total = 36

" F ""

"

""

5

**Lewis** **Dot** Rule 3: Too many electrons for the

rule of 8 (2) to accommodate them.

Rule 4: Elements in periods (rows) 3 and greater

can accommodate 10 and 12 electrons if they are

not terminal atoms.

Example 1: What is the **Lewis** **Dot** structure for

SF 2– ion?

""

!!

= charge

initially:

" F

" !!

= left over

S = 6 ""

""

4×F = 4×7

F S F

"

– –

from the

""

""

"

sulfur

charge = 2

F

" "

total = 36

""

6

**Lewis** **Dot** Rule 3: Too many electrons for the

rule of 8 (2) to accommodate them.

Rule 4: Elements in periods (rows) 3 and greater

can accommodate 10 and 12 electrons if they are

not terminal atoms.

Example 1: What is the **Lewis** **Dot** structure for

SF 2– ion?

!! = charge

Thus, there are too : F : !!

= left over

many electrons for the

: F – S–

F : from the

rule of 8 to

sulfur

accommodate. S can : F :

therefore take 10 or 12

7

**Lewis** **Dot** Rule 3: Too many electrons for the

rule of 8 (2) to accommodate them.

Rule 4: Elements in periods (rows) 3 and greater

can accommodate 10 and 12 electrons if they are

not terminal atoms.

Example 1: What is the **Lewis** **Dot** structure for

SF 2– ion?

charge

So, the 4 electrons left

over are placed on the

S atom.

(S is not in a terminal

position.)

:

F

: :

F – –

:

S

F

:

F

:

left over

from the

sulfur

8

**Lewis** **Dot** Rule 3: Too many electrons for the

rule of 8 (2) to accommodate them.

Rule 4: Elements in periods (rows) 3 and greater

can accommodate 10 and 12 electrons if they are

not terminal atoms.

Example 1: What is the **Lewis** **Dot** structure for

SF 2– ion?

2–

initially:

S = 6

4×F = 4×7

charge = 2

total = 36

:

F

: :

F S–

F

– :

:

F

:

after:

12 × : on F = 12 × 6

2 × : on S = 2 × 2

4 × – = 4 × 2

total = 36

U

9

**Lewis** **Dot** Rule 3: Too many electrons for the

rule of 8 (2) to accommodate them.

Rule 4: Elements in periods (rows) 3 and greater

can accommodate 10 and 12 electrons if they are

not terminal atoms.

Example 2: What is the **Lewis** **Dot** structure for

PF 5 ?

initially:

P = 5

5×F = 5×7

total = 40

"

""

"

" F"

"

"

F

"

""

! ""

F" " ! P!

"F "

"

" " " ""

!

F

"

""

""

"

10

**Lewis** **Dot** Rule 3: Too many electrons for the

rule of 8 (2) to accommodate them.

Rule 4: Elements in periods (rows) 3 and greater

can accommodate 10 and 12 electrons if they are

not terminal atoms.

Example 2: What is the **Lewis** **Dot** structure for

PF 5 ?

initially:

P = 5

5×F = 5×7

total = 40

"

""

"

" F"

"

"

F

"

""

! ""

F" " ! P!

"F "

"

" " " ""

!

F

"

""

""

"

11

**Lewis** **Dot** Rule 3: Too many electrons for the

rule of 8 (2) to accommodate them.

Rule 4: Elements in periods (rows) 3 and greater

can accommodate 10 and 12 electrons if they are

not terminal atoms.

Example 2: What is the **Lewis** **Dot** structure for

PF 5 ?

initially:

P = 5

5×F = 5×7

total = 40

""

F

" "

""

""

F P F

"

– –

""

""

"

F

" "

""

""

"F "

" " ! = left over

from the

phosphorous

12

**Lewis** **Dot** Rule 3: Too many electrons for the

rule of 8 (2) to accommodate them.

Rule 4: Elements in periods (rows) 3 and greater

can accommodate 10 and 12 electrons if they are

not terminal atoms.

Example 2: What is the **Lewis** **Dot** structure for

PF 5 ?

initially:

P = 5

5×F = 5×7

total = 40

:

F

: :

F P–

F

– :

:

F

:

""

"F "

" " ! = left over

from the

phosphorous

13

**Lewis** **Dot** Rule 3: Too many electrons for the

rule of 8 (2) to accommodate them.

Rule 4: Elements in periods (rows) 3 and greater

can accommodate 10 and 12 electrons if they are

not terminal atoms.

Example 2: What is the **Lewis** **Dot** structure for

PF 5 ion?

Since there is 1 F

with 7 electrons

and one other

electron left over,

P may assume

10 electrons.

:

F

: :

F P–

F

– :

:

F

:

""

"F "

" " ! = left over

from the

phosphorous

14

**Lewis** **Dot** Rule 3: Too many electrons for the

rule of 8 (2) to accommodate them.

Rule 4: Elements in periods (rows) 3 and greater

can accommodate 10 and 12 electrons if they are

not terminal atoms.

Example 2: What is the **Lewis** **Dot** structure for

PF 5 ?

Since there is 1 F

with 7 electrons

and one other

electron left over,

P may assume

10 electrons.

:

F P–

F

– :

:

F

:

F left over

! = left over

from the

phosphorous

15

**Lewis** **Dot** Rule 3: Too many electrons for the

rule of 8 (2) to accommodate them.

Rule 4: Elements in periods (rows) 3 and greater

can accommodate 10 and 12 electrons if they are

not terminal atoms.

Example 2: What is the **Lewis** **Dot** structure for

PF 5 ?

initially:

P = 5

5×F = 5×7

total = 40

:

F P–

F

– :

:

F

:

after:

15 × : on F =15 × 2

5 × – = 5 × 2

= 40

U

16

**Lewis** **Dot** Rule 3: Too many electrons for the

rule of 8 (2) to accommodate them.

Rule 4: Elements in periods (rows) 3 and greater

can accommodate 10 and 12 electrons if they are

not terminal atoms.

Example 3: What is the **Lewis** **Dot** structure for

I – 3 ion?

17

**Lewis** **Dot** Rule 3: Too many electrons for the

rule of 8 (2) to accommodate them.

Rule 4: Elements in periods (rows) 3 and greater

can accommodate 10 and 12 electrons if they are

not terminal atoms.

Example 3: What is the **Lewis** **Dot** structure for

I – 3 ion?

! = charge

initially

3 × I = 3 × 7

"

I " "" ""

" " I

" " "

" I

charge = 1

"

"

"

total = 22

18

**Lewis** **Dot** Rule 3: Too many electrons for the

rule of 8 (2) to accommodate them.

Rule 4: Elements in periods (rows) 3 and greater

can accommodate 10 and 12 electrons if they are

not terminal atoms.

Example 3: What is the **Lewis** **Dot** structure for

I – 3 ion?

! = charge

initially

3 × I = 3 × 7

"

I " "" ""

" " I

" " "

" I

charge = 1

"

"

"

total = 22

19

**Lewis** **Dot** Rule 3: Too many electrons for the

rule of 8 (2) to accommodate them.

Rule 4: Elements in periods (rows) 3 and greater

can accommodate 10 and 12 electrons if they are

not terminal atoms.

Example 3: What is the **Lewis** **Dot** structure for

I – 3 ion?

! = charge

There is now 9

electrons about

""

:

the central

I – I – I :

"" "

atom and 1 left

over from the

charge.

20

**Lewis** **Dot** Rule 3: Too many electrons for the

rule of 8 (2) to accommodate them.

Rule 4: Elements in periods (rows) 3 and greater

can accommodate 10 and 12 electrons if they are

not terminal atoms.

Example 3: What is the **Lewis** **Dot** structure for

I – 3 ion?

charge

Thus, I

accommodates

""

:

10 electrons

I – I – "

I :

"

!

21

**Lewis** **Dot** Rule 3: Too many electrons for the

rule of 8 (2) to accommodate them.

Rule 4: Elements in periods (rows) 3 and greater

can accommodate 10 and 12 electrons if they are

not terminal atoms.

Example 3: What is the **Lewis** **Dot** structure for

I – 3 ion?

initially

3 × I = 3 × 7

charge = 1

total = 22

I – I –

I

: :

–

after:

6 × : on the

terminal Is = 6 × 2

3 × : on the

central I = 3 × 2

2 × – = 2 × 2

totat = 22U

22

The end of **Lewis** **Dot** rule 3

Do the second exercise in your lab manual using rule 3

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