[PDF] 123 Types of Intermolecular Forces (IF Ion-Dipole IF - UMKC





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Forces intermoléculaires

Forces d'autant plus fortes que les moments dipolaires sont élevés. Interactions entre un dipôle permanent et un dipôle induit – forces de Debye.



5. Les interactions intermoléculaires Questions fondamentales du

5.2 Forces ion-dipôle. 5.3 Forces dipôle-dipôle. 5.4 Forces de London L'interaction dipôle – dipôle concerne les molécules qui contiennent.



Correction - TD n°8 - Dipôles électrostatiques et magnétiques 1

Correction - TD n°8 - Dipôles électrostatiques 1 Interaction ion-dipôle ... due aux charges positives est donc plus intense que la force attractive due ...



Chapitre 7 Cohésion de la matière. Liaisons de faible énergie

interaction entre un dipôle permanent et un dipôle induit (Debye). — interaction entre deux dipôles instantanés ou force de dispersion (London).



ch. ci.4 : liaisons de van der waals et liaison hydrogene - solvants

Interaction dipôle permanent- dipôle permanent : Les molécules polaires modifient mutuellement leurs orientations et tendent à aligner leurs dipôles. 2) Force 



Cours LP203 – 2012-2013 – Chapitre 4 – Le dipôle électrostatique

http://subaru2.univ-lemans.fr/enseignements/physique/02/electri/dipole.html La force résultante exercée sur le dipôle est nulle. - si le dipôle ne peut ...



5. Les interactions intermoléculaires Questions fondamentales du

5.2 Forces Ion-Dipôle. 5.3 Forces Dipôle-Dipôle. 5.4 Forces de London L'interaction dipôle – dipôle concerne les molécules qui contiennent.



6. Les interactions intermoléculaires

interaction dipôle - dipôle. - liaison hydrogène ion - ion. 1000. Interaction force relative. - monopôle dipôle permanente ... ion - dipôle induit.



Modelling approaches for atmospheric ion-dipole collisions: all-atom

1 févr. 2022 Abstract. Ion-dipole collisions can facilitate the formation of atmospheric aerosol particles and play an important role in their.



5. Les interactions intermoléculaires Questions fondamentales du

Quels sont les types de forces intermoléculaires? ion - dipôle induit ... L'interaction dipôle – dipôle concerne les molécules qui contiennent.



Chem Exam Flashcards Quizlet

Ion-Dipole Forces (IDF): When an ionic compound such as NaCl dissolves in water the water molecules arrange their oppositely charged dipole to be attracted to the fully charged ion creating a very strong attractive force called an ion-dipole force Between a polar molecule and a fully charged ion



Chap r 11 In rmolecular Forces - Michigan State University

Dipole–Dipole Interactions or Dispersion Forces • If two molecules are of comparable size and shape dipole–dipole interactions will likely be the dominating force • If one molecule is much larger than another dispersion forces will likely determine its physical properties



123 Types of Intermolecular Forces (IF Ion-Dipole IF - UMKC

• Ion-Dipole forces – IFs between an ion and a nearby polar molecule (ionic compounds like NaCl dissolved in polar solvents like H2O) • Dipole-Dipole forces – IFs between two polar molecules (?+ of one molecule attracts ?-of the other) – Increase with increasing the dipole moment Example: CH3CH2CH3 and CH3CN have almost the



Searches related to force ion dipole PDF

Ion-Dipole Forces - the strongest forces • An ion–dipole force is an interaction between an ion (e g Na+) and the partial charge on the end of a polar molecule/dipole (e g water) • It is especially important for solutions of ionic substances in polar liquids • Example: NaCl(aq) Comparing Intermolecular Forces

Does an ionic bond have a dipole?

Does an ionic bond have a dipole? Yes. Why does an atom with many valence electrons tend to gain electrons rather than lose any? Atoms with many valence electrons tend to have relatively strong forces of attraction between their valence electrons and the nucleus. This makes it difficult for them to lose electrons.

What is a dipole induced dipole force?

Instantaneous dipole-induced dipole forces or London dispersion forces: forces caused by correlated movements of the electrons in interacting molecules, which are the weakest of intermolecular forces and are categorized as van der Waals forces. Dipole–dipole interactions are a type of intermolecular attraction—attractions between two molecules.

What is induced dipole - induced dipole interaction?

Dipole-induced dipole interactions: Dipole-induced dipole interaction involves the attraction between temporally induced dipoles in non-polar molecules. This polarization can be induced either. (a) by a polar molecule or. (b) by the repulsion of the negatively charged electron clouds in a non-polar molecule.

What is an induced dipole moment?

The induced dipole moment is proportional to the strength of the applied field. Instead of DC suppose we apply AC, the induced dipole moment oscillates with the same frequency as applied field. In Raman spectroscopy, the oscillating dipole moment is induced by the electromagnetic radiation.

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12.3 Types of Intermolecular Forces (

I F) •IFs are based on electrostatic interactions between opposite charges, but they are much weaker than chemical bonds for two reasons: - Smaller el. charges are involved - The distances between the el. charges are longer •Covalent radius- ½ the distance between two identical bonded atoms •van der Waals radius- ½ the distance between two adjacent, identical (nonbonded) atoms from different molecules The van der Waals radius of an atom is always longer than its covalent radius-IFs are also called van der Waals forces - Stronger IFs lead to higher Tb and T m values •Ion-Dipole forces -IFs between an ion and a nearby polar molecule (ionic compounds like

NaCl dissolved in polar solvents like H

2 O) •Dipole-Dipoleforces -IFs between two polar molecules (+of one molecule attracts -of the other)- Increase with increasing the dipole moment

Example:

CH 3 CH 2 CH 3 and CH 3

CNhave almost the

same molecular weight and size. Since CH 3 CN is much more polar, its dipole-dipole forces are much stronger and its boiling and melting points, Tb and T m , are much higher. •Hydrogen Bonding-IFbetween molecules containing H-atoms connected to highly electronegative small atoms with lone pairs like F, Oand N - Due to the very high polarity of the H-F, H-Oand

H-Nbonds (the +of His attracted to the -of

the lone pair of F, Oor N)Example: CH 3

OH has an O-H

bond H-bonding•Charge-Induced Dipole forces -Induced dipole- a dipole induced in a particle through a distortion of its electron cloud by an electric field such as a nearby charge or another dipole -Polarizability - the ease with which the electron cloud of a particle can be distorted (increases with increasing the size of the electron cloud and therefore with the molar mass of the particle)

Ion-Induced Dipoleforces -IFs between an ion

and a dipole it induces in a nearby particle

Dipole-Induced Dipoleforces -IFs between a

dipole and a dipole it induces in a nearby particle 2 •Dispersion (London) forces -Instantaneous dipole- a dipole that results from an instantaneous fluctuation of the electron cloud in a particle - The instantaneous dipole can induce a dipole in a nearby particle and create an induced dipolein it

Dispersion (London) forces -IFs between an

instantaneous dipoleand an induced dipolein a nearby particle - Dispersion forces exist between anyparticles, but they are the onlytype of IFs for non-polar molecules and atoms of noble gases

Examples:CH

4 , Cl 2 , CO 2 , Ar, Kr, Xe ... are all non-polar only dispersion forces are present -The strengthof the dispersion forces depends on: •The polarizability(size, molar mass) of the particles size, molar mass dispersion forces •The shapeof the particles - dispersion forces between rod-shaped molecules are stronger compared to spherical molecules of the same size (rod-shapes provide more points of contact)

Example:

The boiling points of the noble gases increase down the group as the molar mass increases

Noble gases

He Ne Ar Kr Xe

T b (C) -269 -246 -186 -153 -108

Molar mass

Dispersion forces

T b

Intermolecular

Intramolecular

3 • Comparing the different types ofIFs - The most common IFs in substances are H- bonding, dipole-dipole and dispersion forces - Dispersion forces are typically more important than dipole-dipole forces, and if they have opposite trends, the dispersion forces dominate

Example:H-halides

HCl HBr HI

T b (K)

188 206 237

Dipole moment

Dipole-dipole forces

Molar mass

Dispersion forces

The dispersion forces dominate the trend and T

b • Comparing the different types ofIFs - H-bonding is typically much stronger than dipole-dipole and dispersion forces for particles of similar sizes

Example:Hydrogen halides

HF HCl HBr HI

T b (K)

293 188 206 237

Molar mass

Dispersion forces

HFbreaks the trend and has an anomalously high

T b due to the much stronger H-bonding forces which are not present in HCl, HBr and HI

Example: Identify the types of IFs and rank

the following substances in order of increasing boiling point, T b CH 3 CH 3 , CH 3 CH 2

OH, CH

3 -O-CH 3 , CH 3 CH 2 CH 2 CH 3 CH 3 CH 2

OHO-H bond H-bonding

dispersion forces polar dipole-dipole forces CH 3 CH 2 CH 2 CH 3 non-polar dispersion CH 3 -O-CH 3 no O-H bonds dispersion slightly polar dipole-dipole CH 3 CH 3 non-polar dispersion forces T b

12.3 Properties of Liquids•Surface tension() - the energy needed to

increase the surface area of a liquid by a unit amount (units J/m 2

To create more surface (surface

molecules), energy is needed to work against this inward force

Liquids tend to assume shapes

that minimize the surface area (spherical drops) with increasing the strength of the IFsSurface molecules experience a net inward force 4 •Capillary action - the rising of liquids in narrow tubes (capillaries) against the force of gravity (results from the competition of two types of forces)

Adhesive forces- between the molecules of the

liquid and the walls of the capillary

Cohesive forces- between the molecules within

the liquid (IFs)

Examples:

The H 2

Olevel rises inside

a narrow glass tube the adhesive forces are stronger; The Hglevel drops inside a narrow glass tube the cohesive forces are stronger •Viscosity () - the resistance to flow -with increasing the strength of the IFs -with increasing the temperature (the kinetic energy of the molecules increases relative to the

IFs of attraction between them)

Examples:CH

3 CH 2

OHis more viscous than CH

3 CH 2 CH 3 H-bonding London forces

Oil and honey flow easier at higher T

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