## Bond Order

Michelle Yu 1L
Posts: 34
Joined: Fri Sep 25, 2015 3:00 am

### Bond Order

I know that when BO=3, it means a triple bond.
However if I get BO=1.5, what kind of bond is that?

Dan Dinh 3K
Posts: 22
Joined: Fri Sep 25, 2015 3:00 am

### Re: Bond Order

Hi Michelle,

I was wondering that too. Does a 1.5 bond order number mean that a molecule has resonance, thus contributing to a more stable structure? Therefore, would a 1.5 bond order mean that it is more stable than a bond order of 1 since its resonance contributes to its stability? I know I just answered a question with another question, but this is something I was wondering as well!

Michelle Yu 1L
Posts: 34
Joined: Fri Sep 25, 2015 3:00 am

### Re: Bond Order

I'm not sure if it has resonance or not, but i know that the bigger the bond order, the more stable the molecule because there are more bonding than aniti bonding i think.

Erin Murashige 1L
Posts: 25
Joined: Fri Sep 25, 2015 3:00 am

### Re: Bond Order

The .5 part of the bond order relates back to resonance structure and resonance hybrid. So with a bond order of 1.5, the bond can either be a single or double bond due to resonance structures. So the 1.5 bond order gives an average between the two types of bonds.

KaylaH
Posts: 26
Joined: Fri Sep 25, 2015 3:00 am

### Re: Bond Order

If Bond order is not a full number, then it does mean resonance structures (combination of single and double, or double and triple) are at play because the electrons are delocalized.

Chloe 3D
Posts: 21
Joined: Fri Sep 25, 2015 3:00 am

### Re: Bond Order

While a fractional bond order is an indication of resonance in most cases, I believe there are some exceptions. Consider the molecule NO, for example. It has a bond order of 2.5. However, because the molecule is composed of only two atoms, there is no possible resonance structure.