What is hydrogen bonds: Definition and 18 Discussions

In chemistry, a hydrogen bond (or H-bond) is a primarily electrostatic force of attraction between a hydrogen (H) atom which is covalently bound to a more electronegative "donor" atom or group (Dn), and another electronegative atom bearing a lone pair of electrons—the hydrogen bond acceptor (Ac). Such an interacting system is generally denoted Dn−H···Ac, where the solid line denotes a polar covalent bond, and the dotted or dashed line indicates the hydrogen bond. The most frequent donor and acceptor atoms are the second-row elements nitrogen (N), oxygen (O), and fluorine (F).
Hydrogen bonds can be intermolecular (occurring between separate molecules) or intramolecular (occurring among parts of the same molecule). The energy of a hydrogen bond depends on the geometry, the environment, and the nature of the specific donor and acceptor atoms, and can vary between 1 and 40 kcal/mol. This makes them somewhat stronger than a van der Waals interaction, and weaker than fully covalent or ionic bonds. This type of bond can occur in inorganic molecules such as water and in organic molecules like DNA and proteins. Hydrogen bonds are responsible for holding materials such as paper and felted wool together, and for causing separate sheets of paper to stick together after becoming wet and subsequently drying.
The hydrogen bond is responsible for many of the abnormal physical and chemical properties of compounds of N, O, and F. In particular, intermolecular hydrogen bonding is responsible for the high boiling point of water (100 °C) compared to the other group-16 hydrides that have much weaker hydrogen bonds. Intramolecular hydrogen bonding is partly responsible for the secondary and tertiary structures of proteins and nucleic acids. It also plays an important role in the structure of polymers, both synthetic and natural.

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  1. P

    Solubility depends on polarity or on the number of hydrogen bonds?

    Does solubility depend on the polarity of the molecule or on the number of hydrogen bonds that are formed with water? For example: CF4 can form hydrogen bonds, but it's not polar. Glucose Is Polar e can form hydrogen bonds. How can I predict solubility? Thanks
  2. samy4408

    Trying to understand alveolar surface tension

    Hello, I learned recently about alveolar surface tension, and the explanation provided in the course was not satisfactory, it said that it is due to the force that pushes water molecules of the outer layer to the inner layers, I don't understand why this force that pushes water toward the cell...
  3. samy4408

    About Van Der Waals interactions

    Hello, when reviewing the types of chemical bonds i was a little bit confused about van der waals interactions, in the definition we talk about momentarily disproportion of electrons that provoke a dipole , and then i read that also include hydrogen bonds . I am a bit confused about van der...
  4. user366312

    How can I calculate hydrogen bonds in a specific direction w.r.t. a C-

    I need to calculate H-bonds in a specific direction of a C-alpha atom of a protein. And, I need to calculate that from a PDB file. Can anyone give me a general guideline/direction/idea regarding how to do that? N.B. I need to write a python program.
  5. D

    Water molecules effect on Hydrogen bonds in precipitation

    Cheers everyone. Can the amount of water molecules added to a solution impact the formation of a salt with its ions mainly bonded through hydrogen bonds with electrostatic like behaviour? Let me give Some background to the question first: I am studying the precipitation of Phosphorous(P) as...
  6. S

    Van der Waals vs. Hydrogen bonds

    I know that the two are different thing, that vdW appears in inert gas crystals and alike while hydrogen bond bonds molecules of water. My question is, how does the potential look for hydrogen bond? For vdWaals we have the two terms proportional to 1/R^6 that describes attraction and 1/R^12...
  7. ReidMerrill

    Hydrogen bonds and binding energy question

    I'm doing a computational lab about binding energy and comparing different methods of solvation. What does positive and negative binding energy signify? Half of the places I look say the more positive the binding energy the stronger the interaction between the molecules. Other places say the...
  8. R

    Can H2S Molecules Form Hydrogen Bonds?

    can H2s form hydrogen bonds i read that H2s can , but I'm not so sure about it .
  9. ELiT.Maxwell

    Maximum number of hydrogen bonds

    like in NH3, maximum number of Hydrogen bonds is 4 and general is 2 ... is it that in any molecule, max number of hydrogen bonds=Hydrogens with +∂ change + lone pairs with -∂ charge (enough polarization by F or O or N and chelated with Cl) now, if that was correct, hydrazine nh2-nh2 forms 6...
  10. Anand Wilson

    Can we break the hydrogen bonds in DNA with Phonon?

    Double stranded DNA are bind with hydrogen bonds in between the nitrogenous bases, Usually we use high temperature for denature,so can we break the hydrogen bonds with phonon because shorter wavelength give rise to heat, weather it is possible to denature the DNA?
  11. mgkii

    Hydrogen Bonds in Water and Ice

    Hi I've read sufficient literature on Ice/Water expansion to understand that when water freezes into a lattice, the hydrogen bonds between molecules are longer than they are in liquid water, hence ice expands. However, everything I've read seems to skip over the reason why with statements like...
  12. M

    How do you find the number of hydrogen bonds between molecules?

    Hey, I'm wondering how you figure out the number of hydrogen bonds acting between molecules. I know each water molecule supposedly makes 4 hydrogen bonds with other water molecules through my reading, but I want to know how many for isopropyl alcohol, which has only one OH group. I know its less...
  13. Q

    What is the role of hydrogen bonds in holding water molecules together?

    I'm a little confused on hydrogen bonds. Here's a sample question and answer I'm having trouble with:1) In a single molecule of water, two hydrogen atoms are bonded to a single oxygen atom by A) hydrogen bonds. B) nonpolar covalent bonds. C) polar covalent bonds. D) ionic bonds. E) van der Waals...
  14. K

    Why are intermolecular HCl molecules among them not considered hydrogen bonds?

    A hydrogen bond is the attractive force between one electronegative atom and a hydrogen covalently bonded to another electronegative atom. Doesn't this apply to hydrochloric acid?
  15. W

    Total hydrogen bonds would exist between the following strands of DNA

    How many total hydrogen bonds would exist between the following strands of DNA and their complementary strands? 1. GCATGC 2. TATGGC
  16. N

    Electrical seperation of hydrogen bonds

    Ok. It's been a long time since chemistry class. Firstly, I'm investigating alternative techniques for cutting paper. Think, a normal sheet of computer printer paper. Disregard for the moment any chemical binders. Paper is close to 100% cellulose. So, cellulose is a polysaccharide which...
  17. H

    Investigating Strength of Hydrogen Bonds: Cyclohexane/Ethanol Experiment

    i'm writing a lab report of an experiment investigating strenth of hydrogen bond. An excess of cyclohexane was mixed with ethanol and there's a decrease in temperature of the mixture. I was told that upon the addition of cyclohexane, the H bonds between ethanol molecules were broken and I don't...