Hydrogen or Covalent, what’s the difference.

[Catharsis]

Hi....

 

I’m trying to wonder what’s the defence between a Hydrogen Bond and a Covalent bond (a polar covalent bond to be exact).

 

Other than hydrogen is so special that it gets it’s own name, even though it’s the same as a polar covalent bond (in theory). I know it ends up being a tenth less stronger than a regular covalent bond, but still?

 

So am I missing anything?

 

Any suggestions, comments or opinions are appreciated...

 

Thank you in advance....

[insane_alien]

its not the same as a covalent bond as no electrons are shared.

 

think of it as being the same as a balloon sticking to a wall through static electricity as compared with it actually being melted onto the wall so that it becomes a part of the wall.

 

and don't listen to pioneer when he shows up(as he eventually will) he is a kook but nobody has the heart to get rid of him.

[CaptainPanic]

The hydrogen bond got its own name because it's very common... because there is so much hydrogen around.

 

The covalent bond is a bond where two atoms share electrons.

 

The hydrogen bond on the other hand is much weaker. A hydrogen atom has no attraction to electrons: it's electronegativity is low. Therefore, when it is bonded to for example oxygen or nitrogen, the electrons in the covalent bond are attracted a bit towards the oxygen or nitrogen... that has the effect that the hydrogen becomes slightly positive.

 

This small positive charge then is attracted to the unbonded electrons of another atom (of again oxygen, nitrogen) that is nearby. This attraction is the hydrogen bond.

 

p.s. I don't think this thread belongs in the biology forum. General chemistry would perhaps be better.

[Catharsis]

Yea - I see the reference to electronegative (whatever) on Wikipedia. So I see - that’s what that means - it has to do with (static electricity type of stuff). Which I guess is a whole other beast...

 

It’s just that my biology book (hence why I cam to biology - although others may be more specialized - I can understand) said how the electrons of hydrogen (in water) spend more time spinning around the oxygen creating negative and positive sides etc... Therefore making it a good environment for mixing stuff in, cleaning and to defy gravity....

 

That’s why I though it sounded like a covalent bond (of sorts)...

 

But Wikipedia dose talk about this electronegative stuff that I get lost real quick with - and now that you said - think of static electricity - I can see that there is something else to pay attention too... I don’t know why it seems to be so hard to understand - it seems like it’s written in code, that Wikipedia article...

 

So I guess I gotta look up, how static electricity works - or “reread” my biology book with this static electricity concept in mind and try and make more sense out of it.

 

But I could have sworn that by having the electron from hydrogen spending more time around oxygen - it makes the hydrogen positive hence attracting other stuff, that I guess is negative... And or, other hydrogens (somehow I guess)....

[DrP]

just a note to add that it happens with Hydrogen rather than larger molecules due to the lack of shielding of the nucleaus in hydrogen - because there are only inner shell electrons, the molecular/atomic radius of the molecule is small so the electrons involved in the bonding from the other atom are closer and more effected by the hydrogen nucleus. As we go down the table, the radius of each atom increases and has more 'layers' os shielding electrons which weaken the effect from the nucleus.

 

I essence, it mainly happens between hydrogen and strongly electronegative atoms such as oxygen and chlorine.

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But I could have sworn that by having the electron from hydrogen spending more time around oxygen - it makes the hydrogen positive hence attracting other stuff, that I guess is negative... And or, other hydrogens (somehow I guess)....

 

Yes, that happens - in H2O for example the electrons that would normally be assosciated with the Hydrogen will be drawn into the outershell of the 'electron greedy' oxygen stabilizing the outershell. It also happens on a benzine ring - the electrons on the hydrogen are drawn into the conjugated structure of the benzine ring. The hydrogen is considered to be electron donating and the ring is considered electron withdrawing. Thus - the hydrogen nucleus ends up with even less shielding round it and forms the strongest types of hydrogen bond.

Edited October 20, 2008 by DrP
multiple post merged

[npts2020]

Catharsis: You have begun to try to understand something that scientists still are researching aspects of. Don't give up if you can't understand everything at first, it is not as easy as watching "Ameican Idol" (not to imply that you do). The concepts you are asking about are important for understanding many areas of science.

[Catharsis]

Oh....

 

I see - that helps a lot - I understand if it’s not all figured out... That explains a lot... I know that we don’t have gravity worked out, so I understand when things get a little “sketchy” (I can put it in perspective)...

 

I didn’t know this was the case here - otherwise, I would have thought it‘s a very poor job of explaining things. Now I can understand....

 

It’s just sometimes things seem to be explained very badly at times and or without rhyme or reason.... Like in my biology book - it started taking about amino acids, fatty acids, simple sugars, nucleotides, carbohydrates, proteins, lipids and nucleic acids just out of the blue - meaning I thought they were going to lead into something...

 

I spent time trying to remember them - but outside of knowing that they exist and one kinda relies on the other, it really didn’t go anywhere. So I guess - it’s the “being exposed” to information over and over as time moves on. Because science can go in so many different directions that sometimes “information” is given for “information sake”....

 

So depending on which direction you decide to go in, information will repeat and be applied appropriately, latter on, in more “job” specific classes..... No?

[DrP]

I thought it was pretty clear cut really. A H-bond is a dipolar attraction between delta- and delta+ areas between molecules. A Covailent bond is the actual overlapping of shells to share electrons across a bond. Very different and is well understood and defined - What is it that we are still researching aspects of then npts?? We we taught about H-bonding quite early in chemistry lessons.

[npts2020]

Well, two areas of research involving hydrgen bonding I can think of off the top of my head include hydrogen storage batteries and drug delivery systems, I am sure I could come up with more.

[pioneer]

The hydrogen bond in water is part (about 90%) electrostatic and part (about 10%) covalent [96]d and may be approximated by bonds made up of covalent HO-H····OH2, ionic HOδ--Hδ+····Oδ-H2, and long-bonded covalent HO-··H––O+H2 parts with HO-H····OH2 being very much more in evidence than HO-··H––O+H2, where there would be expected to be much extra non-bonded repulsion. Hydrogen bonding effects all the molecular orbitals even including the inner O1s (1a1) orbital which is bound 318 kJ mol-1 (3.3 eV) less strongly in a tetrahedrally hydrogen bonded bulk liquid phase compared to the gas phase [1227].

 

 

However, as hydrogen bonding is directional it restricts the number of neighboring water molecules to about four rather than the larger number found in simple liquids (for example, xenon atoms have twelve nearest neighbors in the liquid state.

 

http://www.lsbu.ac.uk/water/hbond.html

 

Typically we express the oxygen of water as having two non bonded orbitals which form hydrogen bonds. This is only partially true, after a hydrogen bond forms. More currents models actually have both non bonded orbitals overlapping, within isolated water, the water looking more like a triangle.

 

The electronic structure has been proposed as 1sO2.00 2sO1.82 2pxO1.50 2pzO1.12 2pyO2.00 1sH10.78 1sH20.78 [71], however it now appears that the 2s orbital may be effectively unhybridized with the bond angle expanded from the (then) expected angle of 90° due to the steric and ionic repulsion between the partially-positively charged hydrogen atoms (as proposed by Pauling over 50 years ago [99]).

 

 

When I defined hydrogen bonding as a reduction of hydrogen, it am proposing a new way to look at it based on the evidence. Sometime I forget what I read years ago. I am not trying to deceive but are trying to be helpful. This approach allows connections that are not obvious without it.

Edited October 28, 2008 by pioneer

[DrP]

Well, two areas of research involving hydrgen bonding I can think of off the top of my head include hydrogen storage batteries and drug delivery systems, I am sure I could come up with more.

 

Fair enough, but so what?, I still don't see how this creates any confusion as to what the differences are between covailent bonds and H-bonds. One being an actualy chemical bond with electron sharing and the other being an electrostatic attraction between 2 molecules with dipolar moments. I think that they are pretty well understood.

[npts2020]

Fair enough, but so what?, I still don't see how this creates any confusion as to what the differences are between covailent bonds and H-bonds. One being an actualy chemical bond with electron sharing and the other being an electrostatic attraction between 2 molecules with dipolar moments. I think that they are pretty well understood.

 

 

I apologize if it seemed like I was saying that little was understood about those topics. I was really only trying to encourage the OP to take enough time to try and understand the subject and point out that research to better understand how to exploit what we know is still ongoing.

[DrP]

Not at all - sorry if I missed your point.

 

Pioneers post goes into more detail, beyond that of what you need to learn for school or for a basic understanding - interesting though.

[Riogho]

Hi....

 

I’m trying to wonder what’s the defence between a Hydrogen Bond and a Covalent bond (a polar covalent bond to be exact).

 

Other than hydrogen is so special that it gets it’s own name, even though it’s the same as a polar covalent bond (in theory). I know it ends up being a tenth less stronger than a regular covalent bond, but still?

 

So am I missing anything?

 

Any suggestions, comments or opinions are appreciated...

 

Thank you in advance....

 

 

From my understanding, Hydrogen Bonding isn't bonding at all. It is an intermolecular force between the mostly positive Hydrogen(attatched to something such as H2O) and another negatively charged source.

 

A good example is water, the electronegativity (Electronegativity is a measure of how strongly an atom pulls on outside electrons) is so much stronger in oxygen than in hydrogen, so hydrogens electron spends most of it's time around the oxygen atom, making the positive end of the molecule be attracted to the negative oxygens of other atoms, the attraction isn't strong enough to have bonding occur, though.

[Catharsis]

Well, like wow - I’m not even going to even begin to try and figure this one out.... But I at least know that something very different is aloof between the two....

 

I‘ll leave it at that - that one is more of attraction, rather, than of sharing... Good enough for me.....

 

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But I tell ya - all that runs through my head (all that could logically run through my head) is this:

 

you got two planet earths (with the moon) - the moon of one planet (hydrogen) get’s pulled by the force of the oxygen atom and instead of going side by side with it’s moon (electron) and spinning around both earths in one big lunar orbit (which would be covalent) the moon of the hydrogen earth just get’s pulled enough to go in between the oxygen earth and moon (hence making it around the oxygen earth only) and then going back (making it “attraction” not bonding) or it doesn’t necessarily make it around the oxygen earth, but rather, turns back before “circling”.

 

Because to me it’s gotta happen one way or the other. That electron (moon) is going to get pulled to the other oxygen earth and turn back before it quite get’s there or it get’s there and just makes it around the oxygen earth and then back (or some variation in between, or not even really). Because if it were to hook up “together” with the oxygen moon then it would be covalent... No?

 

At least as I see it... And also I’m getting the feeling that several different types of bonds (attractions) are going on too at the same time (meaning that it’s not all just one standard type of attraction).

 

But so in closing: I think text books could be written better though - but I suppose a book get’s written under a certain amount of controversy (as we see even in this thread - so I can imagine what goes on with a book) not to unlike politics (meaning, it’s hard to make a push to one side “of things” - but rather the best is the middle ground - mediocrity - it makes both sides content (pacified) it kinda makes things - should I say - homeostasis - ha ha ha).....

[DrP]

Well, like wow - I’m not even going to even begin to try and figure this one out........

.

 

Well why not?

 

 

I‘ll leave it at that - that one is more of attraction, rather, than of sharing... Good enough for me..... .....

 

Well that's pretty much it:

Covailent - sharing of electrons through the bond with overlapping orbitals

Ionic - Strong attraction between highly positive and negaive atoms.

Hydrogen - weak attraction between partially positive and negative areas on a molecule.

 

 

 

 

But so in closing: I think text books could be written better though - ...

 

 

Depends on your text book and what level of detail you wish to know about. When begining chemistry, you usually get tought things as being far simpler than they actually are. As as your understanding grows and you qualify further and further you get introduced to more complicated and advanced models which better explain in more detail what actually happens. Each year as you go through your education in chemistry you learn more complex models to replace the old ones you learnt. Example - it's important to under stand the basics of positive negative attraction between charges and the importance of an atom filling up its outer shell of electrons to become stable, before learning about bonding (because bonding is about getting the atom into a more stable state by filling up shells of electrons to balance charges) -- it get more complicated than that - but you learn the basic need first, otherwise you wont understand the later theorys.

[Riogho]

If you want a good Chem 1 textbook, I reccomend Zumdahl/Zumdahl (Version 7). It's the one I use.

[Catharsis]

Hey yea - that’s a real royal idea - asking the pro’s what book’s (text books or not) to read.....

 

Outstanding good fellow.

 

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I just study this stuff as a way of occupying my time - I’m a live in heath care provider, now on the job with my fourth or fifth patient. Currently (this case is not hospice) so it’s been two years now on the job...

 

Also (I’m afraid) I myself, am getting old (being that I’ve lived an athletic life and around age thirty five is kinda “it”) So I learn about (I guess) the mind and it’s neurons “gerontology” because that’s the way I’m heading and neuron decay seems to be what I’m exposed to (daily) just the nature of the beast.... So I keep up a yahoo 360 page that I use to kill time with - however, with messing around with photo’s, art, exercise, the computer in general, movies, the beach - I bounce around doing many different things....

 

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I really liked that basic comparison a few post’s up... Sometimes that’s all really need and you end up getting the long version...

[pioneer]

With hydrogen bonding there is partial covalent character and partial ionic character. Hydrogen bonding exists somewhere between the two, so it is not one or the other but both at the same time. That is the reality of the latest data. If we assume just ionic, our assumption is not exactly correct. This 90% true assumption of only ionic will cause a compounding error which eventually appears to detach the variable.

 

If you look at water in the cell, if hydrogen bonding is only ionic, it is detached from a protein, conceptually, since the protein is a covalently bonded structure. If we look at the hydrogen bonding in water as partial covalent, it becomes more of a part of the covalent bonding of the protein. If we analyze the protein with the first assumption will have a random variable to account for the 10% left out, which detaches the protein and water in any covalent way that could correlate the water to covalent things the protein is doing. The second is the protein plus water, which is a different phenomena with mores stuff to account for the odd ball.