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Questions tagged [hydrogen-bond]

Intermolecular force between covalently bound hydrogen atom and atom possessing a lone pair of electrons.

A hydrogen bond is is a special case of a dipole-dipole interaction. The interaction is between a hydrogen atom, bound covalently to more electronegative atom, and another electronegative atom possessing a lone pair of electrons.

Hydrogen bonds can be intermolecular or, for molecules with sufficient size, intramolecular. The molecule or part of a molecule with the bound hydrogen is called the donor, and the atom with the lone pair is called the acceptor.

Hydrogen bonds are weaker than covalent bonds, and they form and break more easily. Like covalent bonds, they are directional, i.e. prefer a certain geometry of donor and acceptor. Networks of hydrogen bonds explain why water, which has two donors and two acceptors per molecule, is a liquid under ambient conditions.

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Is a hydrogen bond considered to be a van der Waals force?

Is a hydrogen bond considered to be a Van der Waals force?
TCU828
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Hydrogen Bond Without Hydrogen

Surely, by the same logic, any atom with a moderate electronegativity (carbon, phosphorus, silicon) can form a polarise covalent bond with an atom with a high electronegativity (fluorine, oxygen). Giving that carbon, phosphorus or silicon a…
Alex P
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Strongest hydrogen bond between neutral molecules?

It is known that very strong hydrogen bonds can occur in charged systems, such as $\ce{[F-}\ce{-H+-F-]}$, while hydrogen bonds in neutral systems are much weaker in comparison. What is the strongest known hydrogen bond within the following…
diogom
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Hydrogen bonding in concave rings

Can hydrogen bonding occur if both O and H are in a ring having 6 members however the ring is concave . Example 3 hydroxycyclohexanone
user43496
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Hydrogen bonds: 1 donor with 2 acceptors at the same time possible (or vice versa)?

Can 1 donor (eg N-H) facilitate 2 H-bonds with 2 different acceptors (eg 2x O) at the same time (assuming that both are within range and angle constraint)? i.e. building an "h-bond triangle"? Is it possible the other way round: 2 donors and 1…
lordy
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Hydrogen donor without hydrogen acceptor?

Is there a molecule that can donate a hydrogen to a hydrogen bond but not accept one? It would seem that since the donated hydrogen needs to be bonded to an electronegative atom, that electronegative atom will always have lone pairs available to…
ericksonla
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Hydrogen bond comparison

How do you compare the strength of H bonds when it's the same atom on both sides of the H? Like $\ce{N-H\bond{...}N}$ vs $\ce{F-H\bond{...}F}$? Is one still stronger than the other, or are they both the same since in both cases the pull on both…
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Why H2O is a liquid (water) and H2S is a gas?

I always think about this question. Is it due to attraction or repulsion or is there something else that makes one of them a gas and the other a liquid (water)?
user55439
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Why does the distance between atoms in a hydrogen bond impact the strength of the bond?

Wouldn't the distance be irrelevant as after they are attracted they will just close the gap? E.g. once 2 magnets are close enough to be attracted, isn't the distance irrelevant to the strength of the bond between the magnets as they will just…
K-Feldspar
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Why acetaldehyde and acetone have almost equal water solubility?

Given that boiling point of acetaldehyde and acetone are different due to H-bonding, why doesn't H-bond affect the solubility of these compounds in water?
Dev
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How polarization effects from cations affect H-bond strength

The average hydrogen-bond strength in pure water is higher than the average H-bond strength between the first and second hydration shells around a $\ce{Al^3+}$ ion (or any cation, for that matter). This leads to a shift in the OH stretch toward the…
Yoda
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Why are Hydrogen bonds directional?

While reading about Hydrogen bonding in a book (O.P. Tandon's G.R.B. Organic Chemistry), I came across a sentence that was mentioned in a rather unstructured way relative to how comprehensive I was finding it until then. Here is the excerpt of…
Desai
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What is Hydrogen bond Auto-correlation function

Can somebody explain the Hydrogen bond Auto-correlation function in Computational Chemistry (Molecular Dynamics and Simulations) and what does Intermittent and Continuous Hydrogen bond means? Why the graph decays over time? and it's…
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Distinguishing atom types

How does one recognize lipophilic points, hydrogen bond acceptors and hydrogen bond donors in organic molecules? For example, provided this SMILES instance O=C1NC(=O)SC1Cc3ccc(OCCN(c2ncccc2)C)cc3 I know it contains 2 lipophilic points, 5 hydrogen…
Rail Suleymanov
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Why does hydrogen bonding require a lone pair?

Why does hydrogen bonding require a lone pair of electrons on the partially negative atom? They would still be partially negative even without the lone pair right? Or does a bond exist, but is much more negligible compared to when a lone pair is…
Hayden Soares
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