Types of Solids

List the four types of solids illustrated in Model 1.

Complete columns A–C in the table below by referring to the examples in Model 1. Place a check in the box that appropriately describes the types of atoms that are usually seen in each type of solid.

Then, complete columns D and E in the table below by referring to the examples in Model 1. Place an X in the box that appropriately describes the arrangement of atoms or molecules in the solid (either molecular—distinct molecules, or formula units—repeating units in three dimensions with no distinct molecules).

Finally, there are four possible forces of attraction that hold atoms or molecules together in a solid:

covalent bonds, ionic bonds, metallic bonds and intermolecular forces. These depend on the type

of atoms in the solid and whether the connections are between ions, atoms or molecules. Within your group, discuss the type of attractive forces that are most likely holding the atoms or molecules together in each type of solid. List your answers in column F in the table below.

For each type of solid in Model 1, indicate the type of attractive forces that are broken upon

melting, and describe the individual particles that make up the resulting liquid.

Match the following descriptions with one of the four types of solids.

If a particular solid had very strong attractive forces, would you expect the melting point of that

solid to be relatively high or relatively low? Explain your reasoning.

Notice that the substances listed in Model 2 are the same as those in Model 1.

Which type of solid has the lowest melting points?

Is your answer in Question 6 consistent with your answer to Question 5?

The enthalpy of fusion given in Model 2 for each substance is a measure of the energy (in kJ) needed to melt a mole of that substance.

Which type of solid has the lowest enthalpies of fusion?

Is your answer in Question 7 consistent with what you know to be the relative strength of the four types of attractive forces? Explain why or why not.

Using both melting point data and enthalpy of fusion data, rank the remaining three types of solids from weakest attractive forces to strongest attractive forces. Make sure there is consensus in your group before moving on.

1. Metallic Solids
2. Molecular Solids
3. Ionic Solids
4. Covalent Solids

Use the concepts you have learned in this activity to predict the type of solid for each of the fol-

lowing substances. Anyone in your group should be able to justify your group’s answers.

Refer to Model 3.

Which type(s) of solid is generally very soluble in water?

Which type(s) of solid is least soluble in water?

Refer to Model 3.

Which type of solid is most conductive in the solid state?

Use the concepts you have learned about the type of solid in part a to explain why it is conductive in the solid state.

Explain why ionic substances would be conductive after they are melted, even though they are not conductive as solids.