Question

Draw Lewis structures for the following compounds.

a)  HCN

b)  CS2

C)  HCCH 

 

Answer 1

a) Since the centre atom is C as it is less electronegative ( H can never be centre atom as it has 1 electron only) with 4 valence electron

And H has 1 valence electron so it will make 1 bond with C to complete its octet 

And N has 5 valence electrons so it will make 3 bonds with C to complete its octet 

Hence N will remain with 2 valence electrons and C and H with 0 as C is making 4 bonds using all 4 electrons and H is making 1 bond using 1 its 1 valence electron

hence the below Lewis structure 

 

b) Since the centre atom is C as it is less electronegative with 4 valence electron

And S has 6 valence electrons so it will make 2 bonds with C to complete its octet 

Hence S will remain with 4 valence electrons and C  with 0 as C is making 4 bonds using all 4 electrons with 2 S

hence the below Lewis structure 

 

c) Since the centre atom is C as it is less electronegative ( H can never be centre atom as it has 1 electron only) with 4 valence electron

And H has 1 valence electron so it will make 1 bond with C to complete its octet 

And C with make total 4 bonds, 1 with H and 3 with other C to complete its octet 

Hence both C will remain with 0 valence electron and H with 0 as H is making 1 bond using 1 its 1 valence electron and C is making 4 bonds using all its 4 valence electrons

hence the below Lewis structure 

Answers can be found in the Explanation section.