DISCUSSION OF MULTIPLE BOND

 MULTIPLE BOND

EXAMPLE 1

STEP 1 : Draw the correct Lewis structure. 

                                     STRUCTURE 1                                         STRUCTURE 2 

                   (Lewis structure without label)                    (Lewis structure with label)

Diagram 1: Lewis structure that be used to count the total number of electron pairs in                    C1 & C2

STEP 2 : Write the total number of electron pairs of central atoms

C1 & C2  have the same number of electron pairs. 

Thus, number of electron pairs for C1 & C2 = 2

STEP 3 : State the type of hybridization (On the central atom)

C1 & C2  = sp (based on the no. of electron pairs will indicate the type of hybrid)

STEP 4 : HYBRIDIZATION PROCESS

Table 1 : Process of hybrid in C2H2 

STEP 5 : Show overlapping of the orbitals

Overlapping unhybridized 2p orbital of C1 & C2 are represented with red and blue color. Moreover, overlapping between 2 unhybridized 2p orbital of C must be in parallel position in order to form pi bond. It is because the overlapping of orbitals to form pi bond is sideway.  

STEP 6: Explanation of sigma & pi bonds

Formation of sigma bonds:-

1.  1 of sp hybrid orbital of C1 is overlapping end to end with 1 of 1s orbital of H atom         to form 1 sigma bond.

2.  1 of sp hybrid orbital of C2 is overlapping end to end with 1 of 1s orbital of H atom         to form 1 sigma bond.

3.  1 of sp hybrid orbital of C1 is overlapping end to end with 1 of sp hybrid orbital of         C2 to form 1 sigma bond.

4. 2 of unhybridized 2p orbitals of C1 are overlapping sideway with 2 unhybridized 2p        of C2 to form 2 pi bonds.

EXAMPLE 2

STEP 1 : Draw the correct Lewis structure. 

Diagram 1: Lewis structure that be used to count the total number of electron pairs in    C1 , C2 & C3

STEP 2 : Write the total number of electron pairs of central atoms

C1 has amount of electron pairs.

C2 & C3  have the same number of electron pairs. 

Thus, number of electron pairs for :- 

1) C1    = 4

2) C2 & C3 = 3

STEP 3 : State the type of hybridization (On the central atom)

C1 = sp3

C2 & C3  = sp2 (based on the no. of electron pairs will indicate the type of hybrid)

STEP 4 : HYBRIDIZATION PROCESS

Table 2 : Process of hybrid in CH3CH=CH2  (FOR C1 atom)

Table 2 : Process of hybrid in CH3CH=CH2  (FOR C2 & C3 atoms)

STEP 5 : Show overlapping of the orbitals

Overlapping unhybridized 2p orbital of C2 & C3 are represented with blue color. Moreover, overlapping between 2 unhybridized 2p orbital of C must be in parallel position in order to form pi bond. It is because the overlapping of orbitals to form pi bond is sideway.  

STEP 6: Explanation of sigma & pi bonds

Formation of sigma bonds:-

1.  3 of sp3 hybrid orbital of C1 are overlapping end to end with 3 of 1s orbital of H             atoms to form 3 sigma bonds.

2.  1 of sp3 hybrid orbital of C1 is overlapping end to end with 1 of sp2 hybrid orbital         of C2 to form 1 sigma bond.

3.  1 of sp2 hybrid orbital of C2 is overlapping end to end with 1 of sp hybrid orbital         of  C3 to form 1 sigma bond.

4. 2 of sp2 hybrid orbital of C3 are overlapping end to end with 2 of 1s orbital of H to            form 2 sigma bonds.

5. 1 of unhybridized 2p orbitals of C2 is overlapping sideway with 1 unhybridized 2p        of C3 to form 1 pi bond.