Simple structures and bonding models

[lan418]

Problem:

 

Use simple structure and bonding models to account for each of the following.

a) the bond length between the two carbon atoms is shorter in C2H4 than in C2H6.

b) The H - N - H bond angle is 107.5 degrees in NH3.

c) The bond lengths in SO3 are all identical and are shorter than a sulfur-oxygen single bond.

D) The I [3-] ion is linear. Note: the brackets [] indicate the ionic charge.

 

 

 

 

How do i approach this? i dont understand what they want, the molecular geometry ? the shape?

[Neurocomp2003]

a) there asking why the distance(bond length) of C2H4 is shorter than C2H6....which is because of the forces involving the Hs and also the double and single bond. Must also apply knowledge of valence electrons and stuff.

b)HNH its a geometric thing that involves understanding the equal forces amongst the 3 H atoms...(that is equally spaced)...

draw this one out and use geometry to get that angle

c) SO3,---> just show that the electron sharing is equal therefore identical....SO bond itself i'm guessing is the double and single bond issue again(valence electrons)

d) I-I-I, just show that the valence electrons are evenly distributed to both outside Is and that the outside Is don't interact.

and there is no polarity(the water molecule isn't linear because of these 2 things)

[agaubr]

a) The fact of the ethylene witha sigma bond and a pi bond for the double bond causes the atoms to be closer togther due the pi bond mst overlap the p-orbitals for bonding

b) H-N-H bond is from thefact ammonia is sp3 hybrid which is teterahedral where the bond should be 104 deg 28 minutes, but hte wider angle is due the lone pair of electrons on the ammonia and causes the tetrahedreal to distort

c) SO3 bondlinks are shortew due the fromation of resonance stabilized structures with electron sharing on all three bonds being the same