which Intramolecular forces are stronger?

[keliao]

I always thought that Covalent are stronger than Ionic. Iguess it all depends on what kind of compounds you campare it with. am i right?

Type of bond or attraction Range of bond energies, kJ/mol
Ionic bonds 700-4000 Covalent triple bonds 800-1000

Read more: http://science.jrank.org/pages/984/Bond-Energy.html#ixzz0GDTVaNEV&B

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[nze82]

To my knowledge Covalent bonds are ALWAYS stronger than Ionic bonds. I'm not sure where you've gotten those numbers from.
Think about it...
Glucose C6H12O6 is held together by covalent bonds between C, H, and O. If you put glucose in water, glucose molecules do not dissociate. They remain unchanged as C6H12O6 molecules.
On the other hand, NaCl is held together by ionic bonds. You put NaCl in water, and it dissociates (bonds break) into Na+ and Cl- ions immediately.

Another example that shows how weak ionic bonds really are is the association of peripheral proteins with the cell's membrane. Peripheral proteins are associated with the membrane via ionic interactions, which could be disrupted simply by changing the salt concentration of the solution.

Yet, another example of weak ionic bonds is the interaction of the substrate with the active site of the enzyme. Charged groups on the substrate interact with charged groups on at the active site to place the substrate in the proper orientation. But the minute the reaction is done, these ionic interactions are disrupted and the product is released.

I can go on for ever...

The point is Ionic interactions seem to always be weaker than covalent interactions.

 

[joonkimdds]

Covalent bond for the win~!
but don't get confused when it comes down to boiling point.
Although stronger bonds means higher BP, we only care about intermolecular force, not intra.

 

[nze82]

Covalent bond for the win~!
but don't get confused when it comes down to boiling point.
Although stronger bonds means higher BP, we only care about intermolecular force, not intra.

You should really think about getting some sleep Joonkimdds it's 3:40AM dude!

 

[peyman2002]

To make it more difficult, Metallic bonding is also a type of intramolecular bond, so this must be stronger than covalent, right?

 

[peyman2002]

To my knowledge Covalent bonds are ALWAYS stronger than Ionic bonds. I'm not sure where you've gotten those numbers from.
Think about it...
Glucose C6H12O6 is held together by covalent bonds between C, H, and O. If you put glucose in water, glucose molecules do not dissociate. They remain unchanged as C6H12O6 molecules.
On the other hand, NaCl is held together by ionic bonds. You put NaCl in water, and it dissociates (bonds break) into Na+ and Cl- ions immediately.

Another example that shows how weak ionic bonds really are is the association of peripheral proteins with the cell's membrane. Peripheral proteins are associated with the membrane via ionic interactions, which could be disrupted simply by changing the salt concentration of the solution.

Yet, another example of weak ionic bonds is the interaction of the substrate with the active site of the enzyme. Charged groups on the substrate interact with charged groups on at the active site to place the substrate in the proper orientation. But the minute the reaction is done, these ionic interactions are disrupted and the product is released.

I can go on for ever...

The point is Ionic interactions seem to always be weaker than covalent interactions.

I dont agree with your last 2 examples cause ionic bond is an intramolecular type of bond, not INTER. the only INTERmolecular bonds are H-bonds, dipole - dipole and dispersion forces.

 

[jay47]

Covalent bonds are not necessarily stronger than ionic. You don't compare bonds by how they dissolve in water, you judge them by how much energy it takes to break the bond thermodynamically. In most cases, two completely oppositely charged ionic atoms will take more energy to separate than two covalently attracted molecules.

Remember, ionic and covalent are really arbitrary denotations anyways; I believe anything with a difference of EN of 3.5 is described as "ionic" and anything with a difference under that is "covalent".

 

[nze82]

I dont agree with your last 2 examples cause ionic bond is an intramolecular type of bond, not INTER. the only INTERmolecular bonds are H-bonds, dipole - dipole and dispersion forces.

You're right! I think I got carried away trying to show ionic bonds are weak!

 

[keliao]

mmmmm thanks for replying guys..!!....

 

[purplepanda]

Convalent bonds are weaker overall.

Ask yourself, which compounds have a higher melting point (usually)? Ionic Bonds. Higher BP? Ionic Bonds.
Ionic bonds are stronger. It is this attractive force between the cation and anion that create a very strong bond. have higher melting points due to stronger electrostatic forces between ions.

Covalent bonds share electrons. They contain discrete molecular units with weak intermolecular forces = low melting points.

Why the debate and confusion? Because these values vary. From the website you provided, we see an overlap. This means that sometimes an ionic bond can be weaker than a covalent bond and vice versa. But overall, ionic bonds are stronger because a majority of them seem to follow the trend of high BPs, high melting points.

"Ionic bonds 700-4000 Covalent triple bonds 800-1000 " <----see the Ionic bonds in the 700's? They would be WEAKER than Covalent bonds. Those covalent bonds on the high ends would have large dipoles. Thus a larger difference in their electronegativity, kind of this partial + /partial - thing.

 

[purplepanda]

To my knowledge Covalent bonds are ALWAYS stronger than Ionic bonds. I'm not sure where you've gotten those numbers from.
Think about it...
Glucose C6H12O6 is held together by covalent bonds between C, H, and O. If you put glucose in water, glucose molecules do not dissociate. They remain unchanged as C6H12O6 molecules.
On the other hand, NaCl is held together by ionic bonds. You put NaCl in water, and it dissociates (bonds break) into Na+ and Cl- ions immediately.

Another example that shows how weak ionic bonds really are is the association of peripheral proteins with the cell's membrane. Peripheral proteins are associated with the membrane via ionic interactions, which could be disrupted simply by changing the salt concentration of the solution.

Yet, another example of weak ionic bonds is the interaction of the substrate with the active site of the enzyme. Charged groups on the substrate interact with charged groups on at the active site to place the substrate in the proper orientation. But the minute the reaction is done, these ionic interactions are disrupted and the product is released.

I can go on for ever...

The point is Ionic interactions seem to always be weaker than covalent interactions.

The point about Na + and Cl- really doesn't make sense. H2O is a covalent molecule. So when NaCl goes into solution those STRONG forces actually pull apart the H2O molecule.

You know your bio though lol. Geez I gotta study bio more haha!

 

[razblo]

My understanding of ionic bonds is that it's not really a bond because they don't share electrons but rather just an attraction to the atom because of it's opposite charge.

Edit: After re-reading that it might not make a lot of sense but it's the best wording I could come up with.

 

[HowAboutDAT]

so to sum things up, covalent molecules have stronger INTRAmolecular bonds, however ionic compounds have stronger INTERmolecular bonds?