relationship between bond strength, energy, and stability.

[muhali3]

Can someone tell me the relationship between bond strength, bond stability, and bond energy? I'm getting confused and am hearing different things.

The way I understand it... Stable bonds are weak bonds and therefore have low energy. Unstable bonds are strong bonds and have high energy.

??? is that right?

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[Cruzerthebruzer]

Stable bonds are strong bonds. If something requires little energy to break, or is relatively weak, it's unstable.

Compare a hotdog to a metal post, it takes little energy to break the hotdog but a lot to break the metal post, the metal post is also more sturdy/stable/strong.

Yeah, hotdogs and metal posts. Sounds like a post made after 1am.

 

[muhali3]

ok.

so.

shorter = stronger = stable = high bond energy

yeah?

cool.

 

[exquisitemelody]

You could remember the relationship about bond length if you think about a short wooden board and a long one. Which one is easier to chop in half? The long one. Therefore, that one is weaker.

 

[muhali3]

ok so, why do I hear sometimes that stable bonds are low energy? I assume they're referring to a different type of energy, not bond energy?

 

[ThunderBear]

I wish someone had followed up on this question.

My current understanding of bond energy is as follows...

1. Bond energy = energy required to break the bond.

2. Using above definition. Stable bonds are difficult to break and are therefore high in energy. Summarizing: Strong=Stable=High Energy=Shorter.

3. I think that when talking about stable bonds as being "low in energy" that refers to the change in free energy for the reaction. A bond that is strong will not readily react since it is already stable. Therefore it is low in free energy where free energy is the capacity to do work. Conversely a bond that is high in free energy is not stable and can release energy to form more stable bonds. Remember that forming bonds releases energy.

I know this thread has been neglected for a long time, but it's #1 on google so I'll give it some love.

 

[Temperature101]

ok so, why do I hear sometimes that stable bonds are low energy? I assume they're referring to a different type of energy, not bond energy?

They have low(er) potential energy in the energy diagram but more energy is needed to break the bonds that make the molecule.

 

[gwjib04]

High-energy bond is reactive, unstable, weak and probably long

High bond-energy is unreactive, stable, strong and probably shorter


Word order is absolutely critical here. (Summarized from TBR book section on thermochem.) BTW, yes the "high-energy bond" one would be higher on a reaction diagram

Glad you all brought this post up because its a messy jargon the chemists have for this stuff.

 

[circulus vitios]

ok so, why do I hear sometimes that stable bonds are low energy? I assume they're referring to a different type of energy, not bond energy?

It's an incredibly stupid convention and whoever invented it should be whipped.