How to Construct the Lewis Structure for Silicon Dioxide (SiO2)?

To construct the Lewis structure for the covalent compound silicon dioxide (SiO₂), we start with determining the total number of valence electrons.

1. **Calculate the Total Number of Valence Electrons**: Silicon (Si) is in group 14 of the periodic table, meaning it has 4 valence electrons. Oxygen (O) is in group 16, having 6 valence electrons. In SiO₂, there is one silicon atom and two oxygen atoms. So, we calculate:

• Valence electrons from Si: 1 x 4 = 4
• Valence electrons from O: 2 x 6 = 12

Adding these together gives us:

• Total valence electrons = 4 (from Si) + 12 (from O) = 16 electrons

2. **Draw the Skeleton Structure**: Silicon is less electronegative than oxygen, so it will be the central atom. The skeleton structure will look like this:

    O
    |
Si -- O

3. **Distribute Electrons**: Start by placing single bonds between the Si and each O. Each bond uses 2 electrons, so we subtract 4 electrons from the total:

• 16 (total) – 4 (used) = 12 electrons remaining

4. **Complete the Octets for Oxygen**: Each oxygen needs 8 electrons to complete its octet. We can place 6 more electrons on each oxygen (3 pairs), giving:

    :O:
    |  
:O: -- Si

Now, the account for the electrons is:

• 4 (used in bonds) + 12 (6 on each O) = 16 electrons, which is correct.

5. **Check for Octets**: The Si also needs to satisfy the octet rule. Therefore, we can form double bonds between Si and both O atoms:

      O
     // 
:O: = Si = O:

This setup uses all 16 electrons and satisfies the octet rule for all atoms involved.

In conclusion, the Lewis structure for SiO₂ shows silicon at the center bonded to two oxygen atoms via double bonds, fully utilizing the available valence electrons.