Inter molecur forces.........

[aamera]

What type of inter molecular forces are present in NH4OH?

[Cap'n Refsmmat]

Well, think about it. Would hydrogen bonding work in [ce]NH4OH[/ce]? Hydrogen bonding requires a hydrogen atom and an oxygen, nitrogen, or fluorine atom...

[ChemSiddiqui]

Ionic and covalent. If we dissociate the said molecule what is formed? NH4+ and OH- . So forces holding the molecule together is ionic while NH4 will be formed from covalent bonding!

[Cap'n Refsmmat]

He asked about intermolecular forces, not intramolecular forces.

[ChemSiddiqui]

He asked about intermolecular forces, not intramolecular forces.

 

OPPS... Sorry I didn't read it properly... !

[aamera]

Well, think about it. Would hydrogen bonding work in [ce]NH4OH[/ce]? Hydrogen bonding requires a hydrogen atom and an oxygen, nitrogen, or fluorine atom...

 

I m also thinking like that. NH4OH is formed when ammonia gas is dissolved in water. Water dissolve ammonia through H-bonding. But in water some part of NH4OH will be dissociate ( weak electrolyte) into NH4+ ions & OH- ions. Now what type of intermolecular forces will be there. Again H-bonding??????????

[hermanntrude]

the molecule NH4OH does not exist in aqueous solution. It is entirely dissociated into NH4+ and OH-

 

It's kind of semantics really but in this case the ionic attraction is intermolecular rather than intra molecular since the two ions are both molecular but not part of the same molecule. However, it's traditional not to refer to ionic bonds as intermolecular, since they're actually a bond, even when in the temporary state we find in a solution of an ionic compound.

 

Hydrogen bonding is also in there along with london dispersive forces. Hydrogen bonding is of course the strongest by far. You could say that there are dipole-dipole interactions but in fact that's what the hydrogen bond is. it's just a REALLY strong dipole-dipole interaction.

[gobin]

On 2/12/2008 at 12:16 PM, hermanntrude said:

......It's kind of semantics really but in this case the ionic attraction is intermolecular rather than intra molecular since the two ions are both molecular but not part of the same molecule. However, it's traditional not to refer to ionic bonds as intermolecular, since they're actually a bond, even when in the temporary state we find in a solution of an ionic compound.

Note- I am a novice and don't know much and I know you know this but i'm just replying to what you wrote for the benefit of anybody like the poster reading.

Ionic bonds are described as intramolecular..  (in the category of covalent bonds and metallic bonds)..

If you were to take the word "molecular"  in inter/intra molecular,  as  literal, then everything falls apart because any intramolecular bond is a bond between two molecular units. So I don't think it is to be taken literally like that.

I think in the case of the words intermolecular and intramolecular, the term molecular really refers more to "molecule"  

So then you at least see that Covalent and Metallic are intramolecular,  

As for ionic,  if for example an ionic compound like sodium chloride were boiled up, you'd get some ionic monomers forming, as well as ionic dimers eg..    

An atom of Na and an atom of Cl  bonded with an ionic bond.  That's clearly intramolecular.

One area where the definition of ionic bonding as intramolecular is a bit silly is in the case of a big crystal, if we take the idea that a big crystal is not a molecule. i.e. the idea that an "ionic lattice" is not a molecule.   But with these particular terms,  an "ionic lattice" would/could be thought of as a molecule.

One person I spoke to thought that the terms intermolecular and intramolecular don't really apply with an "ionic  lattice" 'cos if we understand it as not a molecule, then the terms just don't apply.  

Anyhow ionic bonds are always (or at least usually) described as intramolecular.. 

Also the term has to be stretched a bit, because   an ion dipole interaction is considered to be intermolecular,   A dipole is a type of molecule, but a monatomic ion isn't.  So there intermolecular is not between two molecules. So then the term intermolecular gets stretched to include what can be between an atom and a molecule.   So intermolecular becomes not necessarily only between molecules, but also between an atom and a molecule. 

added- and to maybe put a spanner in the works,  maybe there is a case that they can be described as intermolecular   eg if between two different ionic species  https://sites.duke.edu/thepepproject/module-2-drug-testing-a-hair-brained-idea/teacher-notes-chemical-bonds-and-forces/   "Ionic compounds exhibit electrostatic intermolecular forces that form strong bonds with other ionic species."    Also I notice this link https://www.reed.edu/chemistry/ROCO/Potential/intermolecular_inter.html; (which i'm looking into) describes  ion ion in the same category as ion dipole, as intermolecular.

Edited December 8, 2022 by gobin

[studiot]

8 hours ago, gobin said:

Note- I am a novice and don't know much and I know you know this but i'm just replying to what you wrote for the benefit of anybody like the poster reading.

Ionic bonds are described as intramolecular..  (in the category of covalent bonds and metallic bonds)..

If you were to take the word "molecular"  in inter/intra molecular,  as  literal, then everything falls apart because any intramolecular bond is a bond between two molecular units. So I don't think it is to be taken literally like that.

I think in the case of the words intermolecular and intramolecular, the term molecular really refers more to "molecule"  

So then you at least see that Covalent and Metallic are intramolecular,  

As for ionic,  if for example an ionic compound like sodium chloride were boiled up, you'd get some ionic monomers forming, as well as ionic dimers eg..    

An atom of Na and an atom of Cl  bonded with an ionic bond.  That's clearly intramolecular.

One area where the definition of ionic bonding as intramolecular is a bit silly is in the case of a big crystal, if we take the idea that a big crystal is not a molecule. i.e. the idea that an "ionic lattice" is not a molecule.   But with these particular terms,  an "ionic lattice" would/could be thought of as a molecule.

One person I spoke to thought that the terms intermolecular and intramolecular don't really apply with an "ionic  lattice" 'cos if we understand it as not a molecule, then the terms just don't apply.  

Anyhow ionic bonds are always (or at least usually) described as intramolecular.. 

Also the term has to be stretched a bit, because   an ion dipole interaction is considered to be intermolecular,   A dipole is a type of molecule, but a monatomic ion isn't.  So there intermolecular is not between two molecules. So then the term intermolecular gets stretched to include what can be between an atom and a molecule.   So intermolecular becomes not necessarily only between molecules, but also between an atom and a molecule. 

added- and to maybe put a spanner in the works,  maybe there is a case that they can be described as intermolecular   eg if between two different ionic species  https://sites.duke.edu/thepepproject/module-2-drug-testing-a-hair-brained-idea/teacher-notes-chemical-bonds-and-forces/   "Ionic compounds exhibit electrostatic intermolecular forces that form strong bonds with other ionic species."    Also I notice this link https://www.reed.edu/chemistry/ROCO/Potential/intermolecular_inter.html; (which i'm looking into) describes  ion ion in the same category as ion dipole, as intermolecular.

Welcome gobin, you may consider yourself anovice, but you seem a well informed one.

Normally resurrecting such an ancient thread, rather than starting your own new one, would be inappropriate but I can see how your post follows on from the discussion.

Classifying chemical bonds as inter (between) or intra (within) molecules only makes sense when molecules as indivisuals are actually present.
More advanced authors, such as Cotton and Wilkinson, use the word aggregate, not molecule, to describe ionic bonding in solids.

Quote

...There are a vast number of solid compounds which can be considered as very closely approximating aggregates of positive and negative ions interacting in a purely electrostatic manner.....

Other authors use words like lattice, crystal etc.

So perhaps you would clarify what exactly did you wish to discuss, bearing in mind that science has developed the 'term' molecule considerably since Descartes first introduced the word in the middle 1600s. Indeed some technical disciplines have extended it further from being a definite physical or concrete noun into purely abstract concepts.

 

[exchemist]

41 minutes ago, studiot said:

Welcome gobin, you may consider yourself anovice, but you seem a well informed one.

Normally resurrecting such an ancient thread, rather than starting your own new one, would be inappropriate but I can see how your post follows on from the discussion.

Classifying chemical bonds as inter (between) or intra (within) molecules only makes sense when molecules as indivisuals are actually present.
More advanced authors, such as Cotton and Wilkinson, use the word aggregate, not molecule, to describe ionic bonding in solids.

Other authors use words like lattice, crystal etc.

So perhaps you would clarify what exactly did you wish to discuss, bearing in mind that science has developed the 'term' molecule considerably since Descartes first introduced the word in the middle 1600s. Indeed some technical disciplines have extended it further from being a definite physical or concrete noun into purely abstract concepts.

 

One widely used term for these extended arrays, whether ionic or covalently bound, is "giant structures".