Inter-molecular Forces of Attraction

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Inter-Molecular Forces of Attraction
Instantaneous-Induced-Dipole force of Dipole-Dipole force of attraction Ion-dipole force of attraction Hydrogen Bonding
Origin Generated due to asymmetry produced These forces of attraction exist These forces of attraction Hydrogen bonds are formed
in electron cloud of non-polar between polar molecules. The element occur between polar solvents by an electro-negative
molecules and noble gases. The that is more electro-negative attracts and solutes having ionic element with a non-bonding
electrons temporarily aggregate at one the electron cloud to itself. The dipole bonding between them. The pair of electrons available to
side creating a partial negative pole is further induced into the neighboring partial poles in a polar solvent bond with a hydrogen atom
which is associated with a partial molecules when unlike poles attract dislodge the element with the attached to an electro-
positive pole on the other side. This each other unlike complete charge from negative element
induces another pole in the its bonds
neighboring molecule
Occurrence They occur in noble gases, group VII These forces occur in all polar They occur between a solute They occur in H2O, NH3, HF
elements, non-polar molecules like H2, molecules (that have some dipole having an ionic bond and amongst hydrides of group
N2, O2 and they occur in graphite moment) polar solvent V VI, VII and between all
those molecules having
Fluorine, Oxygen and
Nitrogen in them
Significance The substances at room temperature The molecules align themselves at low It helps in the ions in solid Due to the hydrogen
experience less force of attraction that temperature. However, these forces of state to dislodge form their bonding being so very
is appreciable when temperature is attraction raise the melting and boiling strong bonds and completely extensive (strong), it results
decreased or pressure is increased. points of the elements that they occur dissolve in non-polar solvents in abnormally high melting
They depend upon how rich an in which is something that is not and boiling points for the
electronic cloud is and how much naturally occurring hydrides of groups 5, 6 and
chances of dispersion are there. They 7 irrespective of their
also depend on shape of the molecule original trends
and its molar mass. Higher the MR,
greater the melting and boiling points
Examples Hydrogen gas, Nitrogen gas, Oxygen HCl, H2O, SO2, CO, HF An example is when Sodium Its examples include HF,
gas, Pentane, Xenon is dropped into water. The H2O and NH3, whereas
result is a Sodium cation and Proteins and Amines are
a chloride anion in aqueous naturally occurring
Comparison They are the most commonly found They are considered to be stronger These forces are stronger that They are the strongest of all
forces in non-polar molecules and are than the London Dispersion Forces but both LDF and the Dipole- the forces of attraction due
considered to the weakest amongst all weaker than the rest Dipole forces of attraction but to their extensive bonding
weaker than hydrogen


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