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We need to draw the Lewis structure for both CO2 and SiO2 molecules to understand their bonding and structure. For CO2: 1. Carbon has 4 valence electrons, and each oxygen atom has 6 valence electrons, making a total of 16 valence electrons in CO2. 2. In the CO2 molecule, carbon forms double bonds with oxygen atoms. Each double bond consists of one sigma bond and one pi bond. For SiO2: 1. Silicon has 4 valence electrons, and each oxygen atom has 6 valence electrons, making a total of 16 valence electrons per SiO2 unit. However, SiO2 has a network structure composed of repeating SiO2 units where each silicon atom is linked to four oxygen atoms. So, we need to think of it in terms of the structure. 2. In the SiO2 molecule, silicon forms single bonds with oxygen atoms, and each oxygen atom bridges two silicon atoms. Thus, the Lewis structures give us the first significant difference: CO2 forms a linear molecule with double bonds, while SiO2 has a network structure with single bonds.

For CO2, carbon forms polar covalent bonds with oxygen, but due to the molecule's linear structure, the overall molecule is nonpolar. This means that individual bond dipoles cancel each other out, resulting in an electrically neutral molecule. For SiO2, silicon forms covalent bonds with oxygen, and these bonds are also polar. However, SiO2 has a three-dimensional (3D) network structure where each silicon atom is bonded to four oxygen atoms, and each oxygen atom bridges two silicon atoms. This results in a giant covalent structure. The second major difference is the type of bonds and overall polarity: CO2 forms polar covalent bonds in a nonpolar molecule, while SiO2 has a giant covalent network structure.

Since CO2 has a simple molecular structure and is nonpolar, it has weak van der Waals forces between its molecules. This results in CO2 being a gas at room temperature. On the other hand, SiO2 has a giant covalent network structure, which leads to strong covalent bonds between its atoms. This results in high melting and boiling points, and SiO2 is a solid at room temperature (commonly known as quartz or silica). The third major difference between CO2 and SiO2 lies in their physical properties: CO2 is a gas, while SiO2 is a solid at room temperature, due to the differences in their bonding structures.