Problem 9 - Chemistry A Guided Inquiry

Question

Quartz, \(\mathrm{SiO}_{2}\), is a very high melting, hard solid. Place a point for \(\mathrm{SiO}_{2}\) on the bondtype triangle. What type of bonding would you predict to be predominant in quartz?

Step-by-Step Solution

Answer

The predominant type of bonding in Quartz, or Silicon Dioxide (SiO2), is polar covalent.

Step 1: Identify the Type of Atoms Involved

In our compound, Silicon Dioxide (SiO2), we have Silicon (Si), a metalloid, and Oxygen (O), a non-metal. Mixed bonds usually occur between metals and non-metals.

Step 2: Understand the Types of Bonding

Covalent bonds occur when two nonmetals share electrons in their outer shells, and no charges are produced. Polar covalent bonds occur when two nonmetals share electrons but not equally. One element has a higher electronegativity and attracts more electrons. Ionic bonds involve electron transfer from a metal to a non-metal, resulting in positive and negative ions that attract each other. Metallic bonds occur among metal atoms.

Step 3: Determine the Type of Bonding in SiO2

Since both Silicon and Oxygen have high electronegativities and are non-metals, they are likely to share electrons. Considering the similar electronegativities of these elements (Silicon has 1.90, Oxygen has 3.44), it’s not equal sharing. Thus, they form a polar covalent bond.

Step 4: Locate SiO2 on the Bond type Triangle

The bond type triangle categorizes compounds into regions based on their bonding types: ionic, covalent, or metallic. SiO2 should be placed towards the covalent apex but closer to the polar covalent side because of the differences in electronegativity between Si and O.