KEY2CHEM

Bonding in Solids

The structure of and bonding in a solid directly influences its resulting properties. For example, an ionic solid is hard and brittle due to the regular repeating arrangement of oppositely-charged ions. Collecting experimental evidence of these properties allows for the hypothesis of the solid’s structural composition.


Example 1.

 

A solid is found to conduct heat and electricity. It was also dented when hit with a hammer. What is the most likely identity of the solid?

A. ionic compound

B. metal 

C. covalent compound

 

Solution 

B. metal

In the solid state, metals are good conductors of heat and electricity due to their delocalized electrons. They are also malleable (can be deformed into shapes) because the electrons are not closely localized with any singular metal cation. 


Example 2.

A solid does not conduct an electrical current, either in the solid state or in aqueous solution. It also has a relatively low melting point. What is the most likely identity of the solid?

A. ionic compound

B. metal

C. covalent compound

 

 

 

Solution

C. covalent compound

Covalent compounds are generally poor conductors of heat and electricity because the electrons are localized in covalent bonds. Covalent compounds generally do not dissociate into ions when dissolved in water, which is why the solution does not conduct electricity.


Example 3.

A solid is found to have a very high melting point, and it cracked when hit with a hammer. What is the most likely identity of the solid?

A. ionic compound

B. metal

C. covalent compound

 

 

 

Solution

A. ionic compound

Ionic solids have strong ionic bonds, leading to high melting points. The regular repeating array of oppositely charged ions leads to the hard and brittle nature of ionic compounds, which crack under external force (instead of bending/denting) due to repulsions of like-charged ions.