Chemical Forums
Chemistry Forums for Students => Undergraduate General Chemistry Forum => Topic started by: wonderkid on July 26, 2006, 12:05:43 PM
-
ionic or covalent bond stronger?why?
-
For homolytic bond cleavage or heterolytic?
-
ionic ... i think bcoz it is metal and metal
-
Generally speaking, covalent bonds are stronger than ionic bonds. The ratio of the strength is 100:50, or 2:1.
Covalent bonds include covalent network bonds, which are extremely strong as evidenced by the diamond, which is a prime example of this.
-
Ionic bonds are easily destroyed (Al2O3 for example), while covalent bonds (diamond or water for example are much stronger, thats why we are having a hard time producing hydrogen :)
-
Ionic bonds are easily destroyed (Al2O3 for example)
You mean ionic bonds like in corundum (nothing else but Al2O3, when colored known as ruby or sapphire), one of the hardest minerals known?
-
Ionic bonds are easily destroyed (Al2O3 for example)
You mean ionic bonds like in corundum (nothing else but Al2O3, when colored known as ruby or sapphire), one of the hardest minerals known?
So maybe it's all relative? Perhaps it depends on what you are comparing it to. Like are the ionic bonds in Al2O3 stronger than the covalent bonds of. say BF3 or diamond?
-
So maybe it's all relative? Perhaps it depends on what you are comparing it to. Like are the ionic bonds in Al2O3 stronger than the covalent bonds of. say BF3 or diamond?
That's what I am aiming at - I don't think it is possible to state which of these bonds are stronger in general, as there are awlays counterexamples. Besides, we will have to agree first about what IS the bond strength.
-
COVALENT DUDE. Definetly covalent. You can state it, this is something that is almost ALWAYS true.
I'd bet my life on it.
But be careful, with the covalent bonds because there is intermolecular and intramolecular.
For example if you have a H2 gas floating about.
The H---H bond would be a strong covalent bond.
But the inter molecular bonds between a H2 ----- and another H2 molecule would be weak dispersion forces.
Or in the case of polar molucules, like water, weak dipole-dipole/hydrogen bondnig forces.
Even though the bonds BETWEEN molecules are week, the covalent bonds WITHIN the molecule itself are the strongest there is.
But if it is as lordhokage said a covalent network, then it is stronger still since the whole thing is made up of covalent bonds and no intermolecular forces, as diamond was used as the prime example, i do belive , the strongest thing known. That is, the amount of heat that would be needed to break those bonds is ... astronomical.
but in the case of ionic, wouldn't disolving it in water break the bonds? if not then isn't it closer to covalent?
-
COVALENT DUDE. Definetly covalent. You can state it, this is something that is almost ALWAYS true.
I'd bet my life on it.
But be careful, with the covalent bonds because there is intermolecular and intramolecular.
For example if you have a H2 gas floating about.
The H---H bond would be a strong covalent bond.
But the inter molecular bonds between a H2 ----- and another H2 molecule would be weak dispersion forces.
Or in the case of polar molucules, like water, weak dipole-dipole/hydrogen bondnig forces.
Even though the bonds BETWEEN molecules are week, the covalent bonds WITHIN the molecule itself are the strongest there is.
OK, so we have hydrogen bonding and we can even throw in coordination bonding too. Then there is the question of what phase is the species in. That still makes the point that it is all relative. Depending on the situation ionic bonding can be stronger than certain covalent bonds. The problem is, in most cases, we usually do not do these comparisons, we either compare two different covalent bonds or two different ionic bonds and the reason is it is all relative. ;)
-
Still :( intermolecular forces shouldn't count, we are really talking about the covalent bond right in there in that molecule. So in the defence of covalent bonds, the phase shouldn't matter :-\ :-[
-
Hydrogen bonding is indeed an example of covalent bonding, although it is much weaker than most covalent bonding. I still say, it has to do with the context, and the two things you are comparing. There are some covalent bonds that are fairly easy to break by the way. For example you can easily break the HBr bond by dissolving it in water. But you can't simply break the ionic AgCl bond by doing the same thing. So you could easily say that the ionic bond is stronger than the covalent bond in this case. But how about if they were both in the gas phase, than what? Is it the reverse? It is not that simple for me anyhow, it really depends on the context.
What is your reasoning behind saying that covalent bonding is "always" stronger than ionic bonding?
-
Ionic bonds are easily destroyed (Al2O3 for example)
You mean ionic bonds like in corundum (nothing else but Al2O3, when colored known as ruby or sapphire), one of the hardest minerals known?
I thought Al2O3 is aluminium-dirt? Forgive me, I am not very good at chemistry, but I am pretty sure its very easy to extact pure aluminium out of that.
-
I thought Al2O3 is aluminium-dirt? Forgive me, I am not very good at chemistry, but I am pretty sure its very easy to extact pure aluminium out of that.
Sorry, no idea what you mean by aluminium-dirt. Al2O3 is a very hard ionic substance. That's why aluminium parts - especially these covered electrolytically with thick layer of oxide - are mechanically so resistant. At the same time Al2O3 is rather easily dissolved in acids and bases. See Remove anodised coating (http://www.chemicalforums.com/index.php?topic=7251.0) thread for some details.
Pure aluminium extraction is not that easy; on the commercial/industrial scale it is done electrolytically and it's a nasty process both in terms of amount of energy required (see http://www.world-aluminium.org/production/smelting/index.html) and environment pollution.
-
You guys need to distinguish between homolytic versus heterolytic bond strength, and crystal hardness versus true bond clevage.
-
You guys need to distinguish between homolytic versus heterolytic bond strength, and crystal hardness versus true bond clevage.
This is a very good point. When we cleave an ionic bond, aren't we usually talking a heterolytic cleavage (i.e.-one atom (the nonmetal) is getting more electrons than the other)? I am guessing that homlytic cleavage is possible for ionic bonds (since anything is possible ;)), just extremely unlikely. Also, either could happen for covalent bonds (example, any binary acid). Crystal hardness is definitely not the same thing as bond cleavage energy, thay are measured in completely different ways.
Which brings me to my point, it is very difficult to compare the stregnths of ionic and covalent bonds. They are two different things, and the compounds they form have so many different properties, it is just not a striaght foward simple comparison.
-
Which brings me to my point, it is very difficult to compare the stregnths of ionic and covalent bonds. They are two different things, and the compounds they form have so many different properties, it is just not a striaght foward simple comparison.
I thought it was mine point ;)
-
Which brings me to my point, it is very difficult to compare the stregnths of ionic and covalent bonds. They are two different things, and the compounds they form have so many different properties, it is just not a striaght foward simple comparison.
I thought it was mine point ;)
See second post in this thread. ;)
-
;D, I know Mitch. I have been pressing the same point too ;)
-
Then we are all right. Scooby snacks all around :P