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27 votes
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Dipole moment of cis-2-butene

Mini Research Project Time Updates Added CCSD(T) $n_i$ and dipole moments and tweaked discussion (the delay was caused by a system-wide storage upgrade on the machines which took nearly a week to ...
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27 votes

Is the carbon atom in the carbon dioxide molecule partially positive?

You're correct in assuming that the carbon atom in $\ce{CO2}$ has a partial positive charge. This is because the oxygen atoms are much more electronegative, so they pull the electrons away from the ...
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26 votes
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Is Hexafluorocyclohexane the "Most Polar" Small Molecule?

At first, I thought, that those 6.2 D of O’Hagan et al. have been measured somehow but it as later described, they calculated it (1): A molecular dipole value of 6.2 D for 1 was calculated at the ...
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24 votes

How to calculate molecular dipole moment from a known wavefunction?

The necessary formal derivation has already been nicely done by AngusTheMan. I'll start from the last equation: $$ \langle \mu_{z} \rangle = \langle \Psi | \hat{\mu}_{z} | \Psi \rangle $$ where $\...
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23 votes
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How does a lone pair of a central atom affect the dipole moment?

How does lone pair of a central atom affect the dipole moment? There is no single answer to your question, let me explain. Unlike a typical covalent bond where the electrons are shared between two ...
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23 votes
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Dipole moments of pyrrole and furan

Both pyrrole and furan have a lone pair of electrons in a p-orbital, this lone pair is extensively delocalized into the conjugated pi framework to create an aromatic 6 pi electron system. Where ...
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19 votes
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How to calculate molecular dipole moment from a known wavefunction?

The dipole moment $\mu$ of a molecule is a measure of charge distribution in the molecule and the polarity formed by the nuclei and electron cloud. We can perturb our system with an external ...
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19 votes
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Is dipole moment a vector?

we assume for no particular reason that dipole moments must be behaving like vectors Ah, but there is a reason. Consider the interaction of a molecule with the scalar potential $$ E_{\text{int}} = \...
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18 votes

Is the carbon atom in the carbon dioxide molecule partially positive?

The other answers have done a great job explaining why, even though its bonds are polar, $\ce{CO2}$ lacks a permanent dipole: the molecule's symmetry cancels out the polarity of its bonds. But that's ...
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17 votes
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Is carbon dioxide IR inactive?

I am told that carbon dioxide is IR inactive. You're right, that's not true. Since carbon dioxide is linear it has $3n-5 = 4$ vibrations and they are pictured below. The symmetric stretch does not ...
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17 votes

Why is CO practically nonpolar?

Preliminaries: I am using the wrong (but still common) notation of the dipole moment. Please see the question about the direction of the dipole moment. The reason why carbon monoxide is often ...
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17 votes
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Why is the dipole moment of chloromethane larger than the dipole moment of fluoromethane?

Dipole moment is not just about charges, it also has $L$ term. Bond length of $\ce{C-Cl}$ is greater than $\ce{C-F}$ and in this case, that is more dominating factor. The dipole moment is in order ...
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16 votes

Is Hexafluorocyclohexane the "Most Polar" Small Molecule?

At first I checked common organic compounds and solvents in CRC Handbook [1, 9-59] that have dipole moment above $\pu{4.5 D}$: \begin{array}{llrr} \hline \text{Name} & \text{Formula} & \text{...
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15 votes
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Why don't polar and non-polar compounds dissolve each other?

Very simply, you explain the reason for this solubility rule by taking in consideration the energy requirements for the breaking of intermolecular forces between the molecules in the solute and the ...
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  • 7,086
15 votes

Why do post-Hartree-Fock methods fail to predict the direction of the dipole moment of carbon monoxide?

The question itself is void, as all methods with the exception of Hartree-Fock predict the direction of the dipole moment correctly. Deathbreath found a Full CI calculation in Jeremy P. Coe, Daniel J. ...
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15 votes
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Why does C=O have a larger dipole moment than C-O?

According to Wikipedia, bond dipole moment depends on: Distance between atoms and Overall charge difference, not just electronegativity difference. Resonance tells us that there is some amount ...
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15 votes

Is the carbon atom in the carbon dioxide molecule partially positive?

You are correct, the carbon does have a positive charge. We cannot measure a dipole, but that doesn't prove anything. However, $\ce{CO2}$ does have a quadrupole moment. Imagine a $\ce{CO2}$ molecule ...
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14 votes
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Why is tetrafluoromethane non-polar and fluoroform polar?

Draw the structures in 3D and then you will see why one is polar and the other not. $\ce{CF4}$: As you can see this molecules adopts a tetrahedral geometry which is perfectly symmetrical in every ...
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  • 15k
14 votes

Confusion about direction of dipole arrow in alpha-helices and other molecules

I (accidentally) stumbled upon the following statement in Atkins' "Elements of Physical Chemistry" (p378): We represent dipole moments by an arrow with a length proportional to $\pmb{\mu}$ and ...
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14 votes
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Is Hydrogen Bonding a Type of Dipole Dipole Interaction?

Well, it turns out that this is a very active area of research. I will only summarize what I understand to be true about the covalent nature of the hydrogen bond, so I'm sure the explanation could be ...
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14 votes
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Why are dipoles "permanent/induced dipole permanent/induced dipole" and not just "permanent/induced dipole" once?

Because it takes two to tango. Dipoles interact with each other. A Lone dipole has nothing to interact with (other than an electric field, but if we ignore some externally applied macro field, there ...
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14 votes
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Dipole moment of (1s,2s,3s)-1,2,3-trichlorocyclopropane

The issue stems from the fact that you may not have understood what each bond notation means. Here, the solid wedge indicates that the bond is toward us and so a 3-D view of the same molecule would ...
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14 votes
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Differences between formulae for dipole–dipole interaction energy

They are both dipole-dipole energies as from the link but their contexts are different. Eq. 3 (as numbered in the LibreTexts link), $$V(r) = - \frac{\mu_{1}\mu_{2}}{4\pi\epsilon_{0}r^{3}} \tag{3}$$ is ...
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  • 351
13 votes

Non-zero dipole moment of hydroquinone

According to J. Am. Chem. Soc. 1945, 67 (2), 322–324: Planar configurations for resorcinol and hydroquinone are more acceptable on comparison of experiment and calculation than are the structures ...
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  • 7,940
13 votes

How to explain the dipole moment anomaly of methyl fluoride and methyl chloride with respect to their hydracids?

Summary A systematic examination of the $\ce{CH3F}$ and $\ce{CH3Cl}$ complexes with density functional techniques and high-level wave function theory indicates that the charge-separation within these ...
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  • 4,559
13 votes
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How to identify hydrogen bonds and other non-covalent interactions from structure considerations?

It is safe to say that there will always be intermolecular forces at play. At the time where you will consider these you should already have a good idea about the molecules involved in your system. ...
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13 votes

Is the carbon atom in the carbon dioxide molecule partially positive?

The previous answers by mpprogram6771 and MSalters nailed it. I'd like to add that, as $\ce{CO2}$ is a very small molecule, you can, with a bit of effort, set up a little numeric experiment to answer ...
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12 votes

Dipole moment of cis-2-butene

This was actually an interesting problem. Well, I ran a quick calculation using Avogadro and GAMESS, although other packages would work. This is a CCSD/aug-cc-pVTZ calculation, pretty much the gold ...
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12 votes

Is an ionic bond more like a covalent bond or an intermolecular force?

An ionic bond could maybe be described as an inter-ionic force. All electron interactions are most accurately described by wavefunctions and quantum mechanics, but in practice we use successively more ...
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  • 10.1k
12 votes
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What is the origin of the "positive-to-negative" convention concerning dipole moments in chemistry?

Some sources point out the direction of the dipole moment is convention dependent. Since both conventions are mathematically correct it seems important when solving a problem to identify the ...
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