Question

Many planets in our solar system contain organic chemicals including methane (CH4 ) and traces of ethylene (C2H4 ), ethane (C2H6 ), propyne (H3CCCH), and diacetylene (HCCCCH). Write the Lewis structures for each of these molecules.

Answer 1

Explanation:

Methane (CH₄)

Valence electrons of carbon = 4

Valence electrons of hydrogen = 1  

The total number of the valence electrons  = 4 + 4(1) = 8

The Lewis structure is drawn in such a way that the octet of each atom and duet for the hydrogen in the molecule is complete. So,  

The Lewis structure is:

                H

                 :

     H    :    C   :    H

                 :

                H

Ethylene (C₂H₄)

Valence electrons of carbon = 4

Valence electrons of hydrogen = 1  

The total number of the valence electrons  = 2(4) + 4(1) = 12

The Lewis structure is drawn in such a way that the octet of each atom and duet for the hydrogen in the molecule is complete. So,  

     H         H

      :           :

     C  :   :   C  

      :            :

     H           H

Ethane (C₂H₆)

Valence electrons of carbon = 4

Valence electrons of hydrogen = 1  

The total number of the valence electrons  = 2(4) + 6(1) = 14

The Lewis structure is drawn in such a way that the octet of each atom and duet for the hydrogen in the molecule is complete. So,  

       H         H

         :           :

H    :  C    :   C  :   H

         :           :

        H          H

Propyne (H₃CCCH)

Valence electrons of carbon = 4

Valence electrons of hydrogen = 1  

The total number of the valence electrons  = 3(4) + 4(1) = 16

The Lewis structure is drawn in such a way that the octet of each atom and duet for the hydrogen in the molecule is complete. So,  

       H        

         :          

H    :  C    :   C  :   :   :   C   :  H

         :          

        H    

Diacetylene (HCCCCH)  

Valence electrons of carbon = 4

Valence electrons of hydrogen = 1  

The total number of the valence electrons  = 4(4) + 2(1) = 18

The Lewis structure is drawn in such a way that the octet of each atom and duet for the hydrogen in the molecule is complete. So,  

H    :  C   :   :   :  C   :   C  :   :   :   C   :  H