MrChemKid
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#1
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Can it hydrogen bond? If so why? I though a h atom
had to be in the molecule?
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Zer0.
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#2
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No. The arrangement of the CO2 Molecule is as follows: O-C-O (V Shaped, unfortunately it's a bit difficult to draw). Either of the lone pairs present on the central Carbon atom (Due to it being in group 6 with only two bond pairs there are 4 electrons left over) could not form a bond with the Hydrogen atom due to the small difference in electronegativity between Hydrogen and Carbon. The main reason is because Oxygen, in this instance, has no lone pairs, therefore it cannot bond with the Hydrogen's present in water. However, a molecule such as H2O2 could, considering how in this case both Oxygen atoms have two lone pairs.
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kaen
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So - hydrogen bonding is a special form for permanent dipole-dipole interaction.

If a hydrogen atom is covalently bonded to one of the most electrostatic elements (fluorine, oxygen or nitrogen) the molecule will become polar. water is therefor a polar molecule because the oxygen forms a negative dipole, and the two hydrogen atoms form positive dipoles.

The reason water molecules can form hydrogen bonds with other water molecules is because the hydrogen is attracted to one of the lone pairs of the more electrostatic oxygen in neighboring water molecules. This attraction between hydrogen and the lone pairs of a more electrostatic element is what is known as a hydrogen bond.

The reason CO2 can't hydrogen bond is that there are no lone pairs of electrons. There is a double covalent bond between each of the carbon atoms and the oxygen atoms. Carbon needs to gain four electrons, whereas each oxygen atom needs to gain two. Since the molecule isn't polar and there are no lone pairs of electrons, the partially positive hydrogen atoms of the water molecules aren't attracted to the CO2 molecule, and no hydrogen bond is formed.

A hydrogen atom obviously has to be present in one of the molecules involved in the bonding because of the reasons above, but I've never heard anything to suggest that is has to be in both of them, since a lone pair or electrons can be present without there being a hydrogen atom in the molecule. Someone please correct me though if 'm wrong about this!

That was a very round-a-bout way of answering your question but I hope that helped somehow!
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sdstudent
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(Original post by Zer0.)
No. The arrangement of the CO2 Molecule is as follows: O-C-O (V Shaped, unfortunately it's a bit difficult to draw). Either of the lone pairs present on the central Carbon atom (Due to it being in group 6 with only two bond pairs there are 4 electrons left over) could not form a bond with the Hydrogen atom due to the small difference in electronegativity between Hydrogen and Carbon. The main reason is because Oxygen, in this instance, has no lone pairs, therefore it cannot bond with the Hydrogen's present in water. However, a molecule such as H2O2 could, considering how in this case both Oxygen atoms have two lone pairs.
Just a few corrections:

- The co2 molecule is linear, it is not V shaped.
- Carbon does not have any lone pairs in CO2; it contains two sets of double bonds
- Oxygen in co2, does in fact have lones pairs. Two pairs on each oxygen atom, giving a total of 4 lone pairs.
The main reason for its lack of hydrogen bonding is that each C=O bond has a dipole but they are oriented 180 degrees from each other so they effectively cancel out, resulting in a molecule that does not readily donate electron density, disqualifying it from participating in H bonds. Hope that helps.
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sdstudent
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(Original post by kaen)
So - hydrogen bonding is a special form for permanent dipole-dipole interaction.

If a hydrogen atom is covalently bonded to one of the most electrostatic elements (fluorine, oxygen or nitrogen) the molecule will become polar. water is therefor a polar molecule because the oxygen forms a negative dipole, and the two hydrogen atoms form positive dipoles.

The reason water molecules can form hydrogen bonds with other water molecules is because the hydrogen is attracted to one of the lone pairs of the more electrostatic oxygen in neighboring water molecules. This attraction between hydrogen and the lone pairs of a more electrostatic element is what is known as a hydrogen bond.

The reason CO2 can't hydrogen bond is that there are no lone pairs of electrons. There is a double covalent bond between each of the carbon atoms and the oxygen atoms. Carbon needs to gain four electrons, whereas each oxygen atom needs to gain two. Since the molecule isn't polar and there are no lone pairs of electrons, the partially positive hydrogen atoms of the water molecules aren't attracted to the CO2 molecule, and no hydrogen bond is formed.

A hydrogen atom obviously has to be present in one of the molecules involved in the bonding because of the reasons above, but I've never heard anything to suggest that is has to be in both of them, since a lone pair or electrons can be present without there being a hydrogen atom in the molecule. Someone please correct me though if 'm wrong about this!

That was a very round-a-bout way of answering your question but I hope that helped somehow!
Just wanted to add that CO2 in fact has 4 lone pairs.
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