Questions tagged [dipole]

For questions about the dipole moment of a bond or a molecule; its calculation, comparison with other bonds or molecules, affect on molecular properties, etc.

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10
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2answers
36k views

Why is HCl not considered to have hydrogen bonding?

A molecule that has hydrogen bonding usually follows these two premises. 1.) There is a hydrogen atom involved 2.) Hydrogen must be bonded to a highly electronegative element which are nitrogen ($\ce{...
21
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2answers
5k views

Non-zero dipole moment of hydroquinone

Why does hydroquinone possess a non-zero dipole moment? The $\ce{OH}$ groups present at para positions on the benzene ring should cancel the effect of each other... if there is a plane change then ...
13
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2answers
14k views

Why is CO practically nonpolar?

This question was in my book. According to me CO should be polar as it should have a dipole moment. But I found that the $\sigma$-electron drift from C to O is almost nullified by the $\pi$-electron ...
13
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1answer
8k views

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

I have asked a question loosely asking this, where I confused terms and did not specify what I wanted to know here, so I formed a new question. What are the differences and similarities between ionic ...
28
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2answers
12k views

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

I understand that molecular dipoles are electric dipoles. And electric dipole moment vectors point from the negative to the positive charge. In class we learned to draw these special molecular dipole ...
22
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2answers
45k views

How does a lone pair of a central atom affect the dipole moment?

Dipole moment is the degree of polarity, i.e. the seperation of positive and negative charges. But I am not getting the intuition why and how lone pairs affect the polarity and dipole moment. I cannot ...
18
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3answers
4k views

How to calculate molecular dipole moment from a known wavefunction?

Say I have a molecular wavefunction as a set of molecular orbitals and want to calculate the molecule's dipole moment, but don't know how! I searched a lot but couldn't find any practical example. $$\...
25
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2answers
31k views

Why is water a dipole?

Water ($\ce{H2O}$) is a dipole. The reason why is simply because it is not symmetrical, there are more electrons on the oxygen side than on the hydrogen side, and the electronegativity of oxygen. But ...
7
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3answers
8k views

Why does chloromethane have a larger dipole moment than chloroform?

Why does $\ce{CH3Cl}$, methyl chloride, have a larger dipole moment than $\ce{CHCl3}$, chloroform? Let us consider $\ce{C-Cl}$ bond moment to be $x$ and that of $\ce{C-H}$ bond to be $y$. In $\...
22
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2answers
10k views

Is Hydrogen Bonding a Type of Dipole Dipole Interaction?

I understand that dipole dipole forces is due to the attraction of the different partials charges of atoms in different molecules due to their different electro-negativities. For hydrogen bonding, ...
6
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1answer
3k views

Trend in the boiling point of the hydrogen halides

The boiling points of the hydrogen halides are as follows: $$\begin{array}{cc} \hline \text{Species} & \text{Boiling point / }\mathrm{^\circ C} \\ \hline \ce{HCl} & -85.1 \\ \ce{HBr} & -...
11
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2answers
59k views

Is carbon dioxide IR inactive?

Wouldn't CO2 be IR inactive because of its non-polar bonds?
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3answers
693 views

What are dipole moments in a molecule supposed to act upon?

In a $\ce{CO_2}$ molecule, a total of four electron pairs are shared between the carbon and oxygen atoms, such that 2 pairs are shared between the carbon atom and each oxygen atom. Oxygen has a ...
6
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2answers
70k views

Why don't polar and non-polar compounds dissolve each other?

Dipoles can also be induced in polar and non polar compounds, then why don't they dissolve?
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2answers
1k views

How to identify hydrogen bonds and other non-covalent interactions from structure considerations?

Chemistry is governed by a wide range of interactions, from ionic and covalent bonding, or other types of strong interactions, towards weaker types of bonding, attraction, or repulsion, that typically ...
22
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3answers
10k views

Dipole moments of pyrrole and furan

Why do pyrrole and furan have dipoles oriented in different directions?
13
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1answer
563 views

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

In carbon monoxide the dipole moment (negative to positive) points towards the oxygen, as I explained it in How can the dipole moment of carbon monoxide be rationalised by molecular orbital theory? A ...
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4answers
2k views

What is the origin of the “positive-to-negative” convention concerning dipole moments in chemistry?

I'm a physics professor who often teaches students who have taken a lot of chemistry (read: pre-meds). In physics, the dipole moment of a charge configuration is defined as pointing from ...
15
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1answer
3k views

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

I was checking dipole moment orders, and came across a very peculiar result: Methyl fluoride $(\ce{CH3F})$ has lesser dipole moment than methyl chloride ($\ce{CH3Cl}$), but hydrofluoric acid ($\ce{HF}$...
12
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2answers
9k views

Does the dipole moment increase or decrease by increasing the bond length?

It is established the dipole moment is a result of multiplication of the magnitude of charges (Q) and the distance between them (r). What I understand is that when an electron and a proton get closer (...
2
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2answers
485 views

Which has greater dipole moment: cis-1,2-dichloroethylene or 1,1-dichloroethylene?

Which has greater dipole moment: cis-1,2-dichloroethylene or 1,1-dichloroethylene? I know that dipole moment depends upon the strength of dipole and angle between the dipoles. 1,1-Dichloroethylene ...
10
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1answer
627 views

What is the dipole moment direction in the nitrosonium ion?

In the recent question about the molecular orbitals of $\ce{NO^{$x$}};\ x\in\{-1,0,+1\}$ the follow-up title question arose: Just a random side-question: What’s the dipole moment’s negative and ...
3
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2answers
15k views

Why is fat nonpolar?

Why is fat nonpolar while water is polar? In water there is the $\ce{H-O}$ bond and the $\ce{O}$ is more negative, we have $\text{dipole = charge}* \text{distance}$ A fat molecule is like $\ce{H-O-C-...
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1answer
3k views

Logical way to compare dipole moment

I have to find the decreasing order of dipole moment of $\ce{CHCl3}$, $\ce{CH3Cl}$, $\ce{CH2Cl2}$, and $\ce{CCl4}$. Now I know that in $\ce{CCl4}$ there will be no dipole moment. Now to compare the ...
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1answer
800 views

What are the structures of potassium superoxide and xenon hexafluoride? [closed]

I have 2 questions in mind: 1) What is the structure of the superoxides? More specifically, what is the structure of $\ce{KO_2}$? 2) What is the structure of and dipole moment for $\ce{XeF_6}$?
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3answers
2k views

Is Hexafluorocyclohexane the “Most Polar” Small Molecule?

Earlier this year, there was a lot of attention when all-cis 1,2,3,4,5,6-hexafluorocyclohexane was synthesized*: Notably, C&E News quoted the lead author: This compound is remarkable for being ...
16
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5answers
2k views

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

I had a question about nonpolar molecules that have symmetrical dipole vectors. Let's take $\ce{CO2}$ as an example. Each of the $\ce{C=O}$ bonds are pulling in the opposite way. My teacher says that ...
9
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1answer
81k views

Dipole moment - calculation of percentage ionic character

Question: The dipole moment of $\ce{HBr}$ is $2.60 \times 10^{-30}$ and the interatomic spacing is $1.41$. What is the percentage ionic character of $\ce{HBr}$? What I know is that the percentage ...
17
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2answers
6k views

Dipole moment of cis-2-butene

I need someone to back me up on this before I go confront my teacher: I was doing some analysis of the dipole moment of cis-2-butene. Let's say that the alkyl groups are both on top. Would the dipole ...
13
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1answer
2k views

Why is the dipole moment of chloromethane larger than the dipole moment of fluoromethane?

On the Pauling electronegativity scale, fluorine and chlorine are 3.98 and 3.16, respectively. Since the dipole moment is dependent on electronegativity, why is the dipole moment of chloromethane ...
12
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2answers
8k views

Which intermolecular interaction is dependent on the inverse cube of distance?

The intermolecular interaction that is dependent on the inverse cube of distance between molecules is: hydrogen bond ion-ion interaction ion-dipole interaction London force Inverse ...
3
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1answer
1k views

Is dipole moment a vector?

Isn't it a misconception to assume that dipole moments are similar to vectors in their behavior? My reasons are as follows: Let us take an example: Methane ($\ce{CH4}$) Clearly, the hydrogen atoms ...
8
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1answer
3k views

Why does C=O have a larger dipole moment than C-O?

Why does $\ce{C=O}$ have a larger dipole moment than $\ce{C-O}$? According to me, dipole moment directly depends upon bond length and electronegativity difference. In $\ce{C=O}$ and $\ce{C-O}$, (I ...
8
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3answers
675 views

At what frequency does a non-polar molecule acquire a dipole able to participate in London Dispersion forces?

London Dispersion forces are forces between non-polar non-ionic molecules that the random fluctuation of their electrons makes them temporarily dipoles. What is the frequency that this occurs? Every ...
7
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4answers
35k views

Why is tetrafluoromethane non-polar and fluoroform polar?

Consider the Lewis dot structures of the molecules fluoroform, $\ce{CHF3}$, and tetrafluoromethane, $\ce{CF4}$:   My first line of thought is that both of these molecules are symmetrical (the ...
4
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1answer
5k views

Why does p-dichlorobenzene have zero dipole moment while hydroquinone does not?

At first I thought that both the OH groups would cancel out their dipole moments in hydroquinone. On reading further, I realized that because of the two different planar structures possible, it has a ...
9
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1answer
275 views

Why do we say “approximation” in the dipole approximation in spectroscopy?

In the dipole approximation, the following relation holds: $$ \hat{V} = -\hat{\mu} \cdot \vec{E}. $$ When we say "approximation", I guess we want to point out that we are dealing with linear ...
7
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1answer
1k views

Calculating dipole moments from atomic partial charges

How can I calculate dipole moment of a complex molecule where the partial charges are available from density functional theory? I have the coordinates of each atom from atomistic simulations of an ...
4
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2answers
7k views

Polarity index vs. Dipole moment

I'm looking to find whether water or methanol is more polar, and I'm getting conflicting answers. My textbook says "the polarity of a bond is quantified by the size of its dipole moment." According ...
12
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2answers
955 views

Does 1-bromo-4-chlorobenzene have a permanent dipole moment?

My first thought was there would be a dipole moment as chlorine and bromine are unequal in electronegativity. I have since looked up the electronegativity of both chlorine and bromine through the ...
11
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2answers
18k views

What is the bond angle of water?

I have been trying to find out the bond angle of $\ce{H2O}$, but every site I visit has a different answer. So far, I have found the following angles listed: Site 1: 104.4º Site 2: 107.5º OR 104.5º, ...
11
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2answers
316 views

Why is ammonia still considered polar despite undergoing rapid inversion?

Here it is stated that a molecule with a rotation axis cannot have dipole moment perpendicular to the axis, as any dipole moment would be changed upon rotation about this axis (which preserves the ...
9
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0answers
160 views

Why does 1,4-diiodobenzene have a non-zero dipole moment?

From this answer, I came to know that 1,4-diiodobenzene has a dipole moment of $0.19~\rm D$ in benzene at $20\ ^\circ\rm C$. On the basis of symmetry, I'd expect the bond moments due to the difference ...
8
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1answer
130 views

Dipole Moment of p-dibromobenzene

What is the dipole moment of p-dibromobenzene? I know that p-dichlorobenzene has zero dipole moment, but my teacher said that this is not the case for bromine. I am still confused and feel its dipole ...
6
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1answer
2k views

Why are the dispersion forces in CS2 stronger than the dipole-dipole forces in COS?

London dispersion forces supposedly have the least strength out of all the intermolecular forces. But $\ce{CS2}$, which has only dispersion forces, has a higher boiling point (and thus stronger ...
5
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1answer
354 views

Chemical bonding and dipole moment

We know that ammonia undergoes amine inversion. Why doesn't the dipole moment decrease in ammonia, since the direction of the dipole changes to the opposite direction every time there's inversion? ...
3
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1answer
130 views

What is the potential to use for non-dispersion interactions?

Although liquid argon’s intermolecular potential can be described using a Lennard-Jones (LJ) potential, which takes into account dispersion forces (induced dipole-induced dipole interactions), what ...
2
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2answers
481 views

How does one apply the knowledge of the direction of a molecular dipole moment?

I was watching Khan academy's video about molecular dipole moments, which explained what they are and how they can be calculated. I also read this article. Both sources explain the concept similar ...
2
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1answer
3k views

How to explain the periodic trends in boiling points in groups?

Observing the trend of boiling points of the compounds listed, choose the appropriate terms to fit into the blanks: \begin{array}{lr} \text{Compound}& \text{boiling point}\\\hline \ce{H2Te} &...
2
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1answer
145 views

Why is hydrogen bonding more significant than any other interaction between dipoles?

Solvents can be categorized as polar and protic. I understand that to be protic there had to be a significantly polar bond involving a hydrogen atom. However, how is the a hydrogen bond different in ...