1) a) Complete the table below.

b) Complete the table below.

Molecule	Intermolecular	Intramolecular
	dipole-dipole bonding only dispersion forces only hydrogen bonding and dispersion forces ionic bonds covalent bonding dipole-dipole bonding and dispersion forces	polar covalent pure covalent pure ionic polar ionic 3 dimensional covalent network
	dipole-dipole bonding only dispersion forces only hydrogen bonding and dispersion forces ionic bonds covalent bonding dipole-dipole bonding and dispersion forces	polar covalent pure covalent pure ionic polar ionic 3 dimensional covalent network
	dipole-dipole bonding only dispersion forces only hydrogen bonding and dispersion forces ionic bonds covalent bonding dipole-dipole bonding and dispersion forces	polar covalent pure covalent pure ionic polar ionic 3 dimensional covalent network
	dipole-dipole bonding only dispersion forces only hydrogen bonding and dispersion forces ionic bonds covalent bonding dipole-dipole bonding and dispersion forces	polar covalent pure covalent pure ionic polar ionic 3 dimensional covalent network
	dipole-dipole bonding only dispersion forces only hydrogen bonding and dispersion forces ionic bonds covalent bonding dipole-dipole bonding and dispersion forces	polar covalent pure covalent pure ionic polar ionic 3 dimensional covalent network

Solution

2) Place the following in order of increasing melting temperature. Give reasons for your choice.

Carbon dioxide, silicon dioxide, diamond, sodium chloride, magnesium oxide, water

Solution

Before answering the next question Click to view a summary of bonding and properties of matter.

3) Consider the following, iron (Fe), silicon dioxide (SiO₂), magnesium oxide (MgO) and water (H₂O).

Which one of the above :
- is a weak conductor of electricity and has the lowest melting temperature;

- can conduct electricity only in the molten state;

- sublimes when heated to very high temperatures;

- melts at high temperatures and conducts electricity in both the molten and solid states.

Solution

4) Why does MgO melt at 2,800 ^oC while NaCl melts at 801 ^oC and KCl melts at 770 ^oC ?
a) The reason why MgO has the highest melting point of the three compounds is due to the fact that MgO has: smaller ions with a greater charge bigger ions with a smaller charge smaller ions only bigger ions only

b) The reason why NaCl has a greater melting point than KCl is best described by the fact that KCl has: smaller ions than NaCl ions with a bigger charge than Nacl bigger ions than NaCl ions with a smaller charge than NaCl

No solutions given for this problem. However in order to answer this question take into account that the melting point is indicative of the strength of the force holding the particles together in the solid. These forces are electrostatic in nature and therefore are directly realated to size of charge and indirectly related to the distance between each charge.