CHM 2046C Module 7 II Part Q  Sample Exam

 

Module 7II Q Intermolecular Forces  10 Points

 

Describe the different type of interparticle forces that can occur between atoms, molecules, and ions.

 

There are three major classes of bonds (discussed in Chapters 9 & 10). These are characterized by the behavior of valence electrons in the bond which, in turn, depends upon the electronegativity difference between the elements involved: covalent (sharing of electrons), ionic (transfer of electrons), and metallic (delocalization of electrons)

 

Distinguish the forces called intermolecular forces.

 

 The bonding between molecules, or between molecules and ions can be described as follows:

Intermolecular forces: 

    (a) ion-molecule forces (e.g. salvation)

    (b) Van der Waals forces of attraction

 

What forces are referred to as van der Waals forces?

 

Van der Waals forces can be subdivided into:

(a)   hydrogen bonding

(b)  dipole-dipole attraction

(c)   dipole-induced attraction

(d)   dispersion forces (induced dipole-induced dipole)

 

Draw a flow chart/table or diagram to summarize these intermolecular forces and show an example.

     

 

Type of Interaction 

Factors Responsible

For Interaction 

Approximate Energy (kJ/mol)

 

Example

Ion-dipole

Ion charge, magnitude

of dipole

40-600

Na+…H2O

Dipole-dipole

Dipole moment

20-30

H2O, HCl

Hydrogen Bonding,

X—H…:Y

Very polar X—H bond

And atom Y with lone pair of electrons

5-30

H2O… H2O

Dipole-induced dipole

Dipole Moment of polar molecule and polarizability of nonpolar molecule

2-10

H2O…l2

Induced dipole-induced dipole

(London dispersion forces)

Polarizability

0.05-40

I2…I2