Question

Question on chemical bonding...

Answer 1

Is a double bond twice as strong as a single bond? Do three single bonds hold as
much energy as one triple bond?

From what I've read, they are not, but another source tells me that:

"Triple bonds share six electrons between two atoms and are stronger than double bonds, which share four electrons between two atoms. Single bonds, which share two electrons, are weaker than double bonds."

I've read other sources which state that double bonds are not necessarily twice as strong as a single bond due to some pi-sigma reason. (Note: I have no clue as to what the pi-sigma relations are, because this is the first time that I'm reading about it, plus my teacher has not covered it yet.).

Answer 2

A triple bond is stronger than a double bond which is stronger than a single bond.
However, this does NOT mean that a triple bond is thrice as strong as a single bond, or that a double bond is twice as strong as a single bond.
In fact, a double bond is composed of a single σ-bond & a single π-bond; a triple bond is composed of a single σ-bond and 2 π-bonds. σ-bonds are generally stronger than π-bonds, as the σ-bond is a head-on overlap of the orbitals while the π-bond is a sidewise overlap.

Answer 3

I was hoping for a more in-depth explanation for pi and sigma bonds, and why they are so, but that's fine. Thank You.

Answer 4

@Agent_A : For a thorough treatment of the subject, you may wish to refer to some College or University-level texts on general chemistry. University Chemistry by Peter E. Siska provides a pretty good analysis of the subject for starters.

Answer 5

Thanks. Yes, I've referred to some online sources, but most of them jump into the complicated matters pertaining to pi and sigma. Unless I'm seeking a root explanation further than what my book states (when in fact, the book may already state the root explanation):

"When orbitals overlap
side-by-side, the result is a pi ( 7T)
bond. When orbitals overlap endto-
end, they form a sigma (a) bond.
Two atoms can form only one sigma
bond. A single bond is a sigma bond, a
double bond consists of a sigma bond
and a pi bond, a triple bond consists of
a sigma bond and two pi bonds"

I suppose if that's the case, I'll just have to accept it as is. I just thought there was some more to it. Or rather, I like to break it down until the "Why is it so?" question turns into a "That's just the way it is!" answer...

Thanks again!

Answer 6

@Agent_A : There is as much as you'd want to go (i.e. there are no limits to the extent to which one can stretch the field). For instance, in most molecules, hybrid orbitals (take sp3 for instance) are often present, and the subject isn't as simple as just imagining a head-on overlap of two discrete p orbitals (in the case of a σ-bond) or a sidewise overlap of two p orbitals (for the π-bond) (which is often the case presented in introductory general chemistry texts).

Answer 7

Oh wow...