OCHEM bond strength

[joonkimdds]

---

Members don't see this ad.

Hi, I just went over my old OCHEM class test and found a question
similar to the one explained in Kaplan blue book page 348, 349.
The question sayd " which approach of two atomic orbitals would form the strongest bond?"

The kaplan said
"pi bond are weaker than sigma bond"

That was correct so I got rid of answer choices a and b(because only C and D are sigma bond, sorry for not posting the picture for choices)


so I compared C and D and they were
C) sp -> <- sp
D) sp -> <-ps


what do you think is the answer between C and D?
I have the answer but I won't post it to get the best explanation🙂))


p.s. by the way, do you guys know which is stronger between bonding and anti bonding molecular orbital?
the kaplan blue book on page 348 shows the picture of these but doesn't state which one is stronger.

 

[andyjl]

Hi, I just went over my old OCHEM class test and found a question
similar to the one explained in Kaplan blue book page 348, 349.
The question sayd " which approach of two atomic orbitals would form the strongest bond?"

The kaplan said
"pi bond are weaker than sigma bond"

That was correct so I got rid of answer choices a and b(because only C and D are sigma bond, sorry for not posting the picture for choices)


so I compared C and D and they were
C) sp -> <- sp
D) sp -> <-ps


what do you think is the answer between C and D?
I have the answer but I won't post it to get the best explanation🙂))


p.s. by the way, do you guys know which is stronger between bonding and anti bonding molecular orbital?
the kaplan blue book on page 348 shows the picture of these but doesn't state which one is stronger.

I would think D because you are overlapping the p orbitals to get the pi bond. and since eyou have an s bond already, this makes for a double bond (1 pi and 1 sigma) which is stronger than just an single sigma bond.

just look at the bonding names "bonding" and "anti-bonding"..bonding will be stronger. these are molecular orbitals that i believe kaplan doesn't really delve into. check your gchem book or search online for molecular orbitals and bonding...in short..if you have elecctrons placed in an anti-bonding orbital, it will not have bonding..thats why when you draw out the molecular orbital diagram,,thats why if you tried to make a diatomic helium, it won't work beccause you have two electrons in the non-bonding orbitals which cause it to be very unstable.

 

[hrndawg]

I think that answer c is right in regards to forming a stronger bond. In general, electrons in an s orbital are held closer to the nucleus and therefore form stronger bonds. So an s-p bond is stronger than a p-p bond, although they both form sigma bonds.

 

[joonkimdds]

I would think D because you are overlapping the p orbitals to get the pi bond. and since eyou have an s bond already, this makes for a double bond (1 pi and 1 sigma) which is stronger than just an single sigma bond.

just look at the bonding names "bonding" and "anti-bonding"..bonding will be stronger. these are molecular orbitals that i believe kaplan doesn't really delve into. check your gchem book or search online for molecular orbitals and bonding...in short..if you have elecctrons placed in an anti-bonding orbital, it will not have bonding..thats why when you draw out the molecular orbital diagram,,thats why if you tried to make a diatomic helium, it won't work beccause you have two electrons in the non-bonding orbitals which cause it to be very unstable.

is p + p orbital always pi bond? can it be sigma bond?
kaplan says "when two p orbitals overlap in a parallel fashing, it's pi bond".
and the picture of the C and D were head to head overlap so I think it's sigma bond between p and p.