chemistry dipoles
When a molecule like a carboxylate ION dissolves in solution, does it form ion dipoles with water molecules or are they hydrogen bonds or both?
I.e. COO- ||||||| H-O-H
I.e. COO- ||||||| H-O-H
Ion-dipole attractions only
A molecule is electrically neutral. A carboxylate ion is not a molecule
A hydrogen bond is a partially electrostatic attraction between a hydrogen which is bound to a more electronegative atom such as nitrogen, oxygen, or fluorine, and another adjacent atom bearing a lone pair of electrons.
An ion-dipole force is an attractive force that results from the electrostatic attraction between an ion and a neutral molecule that has a dipole.
A molecule is electrically neutral. A carboxylate ion is not a molecule
A hydrogen bond is a partially electrostatic attraction between a hydrogen which is bound to a more electronegative atom such as nitrogen, oxygen, or fluorine, and another adjacent atom bearing a lone pair of electrons.
An ion-dipole force is an attractive force that results from the electrostatic attraction between an ion and a neutral molecule that has a dipole.
Original post by BobbJo
Ion-dipole attractions only
A molecule is electrically neutral. A carboxylate ion is not a molecule
A hydrogen bond is a partially electrostatic attraction between a hydrogen which is bound to a more electronegative atom such as nitrogen, oxygen, or fluorine, and another adjacent atom bearing a lone pair of electrons.
An ion-dipole force is an attractive force that results from the electrostatic attraction between an ion and a neutral molecule that has a dipole.
A molecule is electrically neutral. A carboxylate ion is not a molecule
A hydrogen bond is a partially electrostatic attraction between a hydrogen which is bound to a more electronegative atom such as nitrogen, oxygen, or fluorine, and another adjacent atom bearing a lone pair of electrons.
An ion-dipole force is an attractive force that results from the electrostatic attraction between an ion and a neutral molecule that has a dipole.
So does that mean a soap will form ion dipoles to water rather than hydrogen bonds at its hydrophillic head where it has a COO- group
Original post by splitter2017
So does that mean a soap will form ion dipoles to water rather than hydrogen bonds at its hydrophillic head where it has a COO- group
ye
A hydrogen bond is a special case of dipole-dipole interactions. It involves attractions between a δ+ hydrogen on one molecule and a lone pair on a very electronegative atom (N, O or F) on another molecule. Note: it's not just electronegative, it has a lone pair too.
Hydrogen bonding can happen between anions and the δ+ hydrogen on water molecules as well
Here is a good explanation of hydrogen bonding. https://www.chemguide.co.uk/atoms/bonding/hbond.html
Hydrogen bonding can happen between anions and the δ+ hydrogen on water molecules as well
Here is a good explanation of hydrogen bonding. https://www.chemguide.co.uk/atoms/bonding/hbond.html
Thank you AftabGujral !
You are very welcome
Original post by AftabGujral
A hydrogen bond is a special case of dipole-dipole interactions. It involves attractions between a δ+ hydrogen on one molecule and a lone pair on a very electronegative atom (N, O or F) on another molecule. Note: it's not just electronegative, it has a lone pair too.
Hydrogen bonding can happen between anions and the δ+ hydrogen on water molecules as well
Here is a good explanation of hydrogen bonding. https://www.chemguide.co.uk/atoms/bonding/hbond.html
Hydrogen bonding can happen between anions and the δ+ hydrogen on water molecules as well
Here is a good explanation of hydrogen bonding. https://www.chemguide.co.uk/atoms/bonding/hbond.html
You say that a hydrogen bond is a dipole-dipole attraction but then say that it's also an ion-dipole attraction. I suppose that it cannot be both.
The link says that the hydrogen bond is an intermolecular force (force between molecules). Then it says that it is the force between the chloride anion and water molecules.
This seems contradictory.
Thanks for the question. I can see what you are getting at.
The uncontroversial (I hope!) bit is that it is a special case of dipole-dipole interactions. What makes hydrogen bonds stronger is that the lone pairs on the electronegative atom (N, O, F) are involved in the attraction to the δ+ hydrogen.
We use this definition at A Level but if we think about it logically, why should it not apply to ions? So when we have hydroxide ions and water, what is the interspecies bonding going to be?
The author of Chemguide says: "A hydrogen bond is made from two parts - a δ+ hydrogen attached to a sufficiently electronegative element, and an active lone pair." And then extends that to explain hydrogen bonding with negative ions.
(The sufficiently electronegative element and an active lone pair bit limits it to N, O and F in polar molecules.)
Cl won't form hydrogen bonds normally in a polar molecule as the lone pairs are at the 3-level and are not active enough. As the chloride ion, with a negative charge, the lone pairs are active enough
The uncontroversial (I hope!) bit is that it is a special case of dipole-dipole interactions. What makes hydrogen bonds stronger is that the lone pairs on the electronegative atom (N, O, F) are involved in the attraction to the δ+ hydrogen.
We use this definition at A Level but if we think about it logically, why should it not apply to ions? So when we have hydroxide ions and water, what is the interspecies bonding going to be?
The author of Chemguide says: "A hydrogen bond is made from two parts - a δ+ hydrogen attached to a sufficiently electronegative element, and an active lone pair." And then extends that to explain hydrogen bonding with negative ions.
(The sufficiently electronegative element and an active lone pair bit limits it to N, O and F in polar molecules.)
Cl won't form hydrogen bonds normally in a polar molecule as the lone pairs are at the 3-level and are not active enough. As the chloride ion, with a negative charge, the lone pairs are active enough
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