Bond Energy vs. Bond Dissociation Energy vs. Stability

[DrMula]

this is correct, right?

higher stability=higher bond dissociation energy (harder to break), but low bond energy
lower stability= lower bond dissociation energy (easier to break), but high bond energy

Thanks!

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[brood910]

"bond energy" actually means the energy required to break a bond.
Some places misuse this term for potential energy.. This is the energy that you use for H = B.E.broken - B.E.formed.

Bond dissociation energy is DIFFERENT from bond energy unless we are talking about diatomic molecules. Bond dissociation energy is for individual bonds while bond energy is for AVG of all bond dissociation energies in the molecule.

I think you are confused with potential energy vs bond energy.

Potential energy is the one that makes bond less stable.
Think of a ball that is on the ground. If it is lifted up in the air, it will tend to go back down = unstable. Thus, longer bond = higher P.E. = less stable

 

[Schenker]

Mostly correct.

higher stability=higher bond dissociation energy (harder to break), but low high bond energy
lower stability= lower bond dissociation energy (easier to break), but high low bond energy

The former is colloquially known as a "low energy bond" and the latter a "high energy bond," but note that these are colloquialisms that mean the opposite of low bond energy and high bond energy, respectively.

 

[dudewheresmymd]

Mostly correct.
The former is colloquially known as a "low energy bond" and the latter a "high energy bond," but note that these are colloquialisms that mean the opposite of low bond energy and high bond energy, respectively.

so b/c the allylic position is more stable after the radical has formed, it takes less energy/easier to break --> lower bond energy --> in everyday language we refer to the actual bond itself as high energy bond? this is counterintuitive? can you clarify?

 

[polyatomic]

so b/c the allylic position is more stable after the radical has formed, it takes less energy/easier to break --> lower bond energy --> in everyday language we refer to the actual bond itself as high energy bond? this is counterintuitive? can you clarify?

The terminology definitely gets confusing here. I recall having a hard time remember what high/low meant for each piece of vocabulary.

I believe what you're talking about ("high-energy bond") is a term more commonly used in biology. We say ATP has a "high-energy bond" it is in a high energy state, and thus has a high energy potential (has lots of energy to give off if the bond is broken). In chemistry we talk more about bond-dissociation energies, which give off a slightly different meaning.

Wikipedia (http://en.wikipedia.org/wiki/Bond-dissociation_energy) does a really nice job here. They present the table below of "bond dissociation energies."

They show that the "STRONGER" bonds have HIGH bond-dissociation energies (like N=N), and are therefore difficult to break because it takes more energy to break the bond. While "WEAKER" bonds have LOW bond-dissociation energies (like I-I), and are therefore easy to break, because you don't need to add as much energy to break the bond.