Draw a Lewis structure for SO(subscript 2) in which all atoms obey the octet rule. Show formal charges.
Draw a Lewis structure for SO(subscript 2) in which all the atoms have a formal charge of zero. Explicitly showing zero charges is optional.
To draw the Lewis Structure for SO2, we need to follow a few steps:
Step 1: Determine the total number of valence electrons.
To calculate the total number of valence electrons in SO2, we need to sum the valence electrons from each atom. In the case of SO2, Sulfur (S) is in Group 6A, so it has 6 valence electrons. Since there are two Oxygen (O) atoms, we multiply Oxygen's valence electrons (Group 6A as well) by 2, giving us a total of 12 valence electrons. Therefore, the total number of valence electrons in SO2 is 6 (from S) + 12 (from two Os) = 18.
Step 2: Connect the atoms with single bonds.
Place the least electronegative atom (in this case, Sulfur) in the center and connect it to the surrounding atoms (Oxygens) using a single bond. As a general guideline, Hydrogen (H) is usually not placed in the center.
Step 3: Place the remaining electrons.
After connecting the atoms, you will have distributed 4 electrons (one bond) from the total of 18 valence electrons. This leaves us with 14 electrons.
Step 4: Distribute the remaining electrons to satisfy the octet rule.
Start placing the remaining electron pairs around each atom to satisfy the octet rule. It is important to distribute electrons as lone pairs on each atom's outer shell, keeping in mind that the central atom (Sulfur) may have more than eight electrons. Remember, the octet rule states that elements tend to share, gain, or lose electrons to achieve a stable configuration of eight electrons in their outer shell.
Step 5: Check if the octet rule is satisfied.
Once all the remaining electrons have been placed, check if the octet rule is satisfied for each atom. In the case of SO2, while Oxygen (O) atoms usually have eight electrons (4 pairs) around them, Sulfur (S) can accommodate more than 8 (6 pairs) due to its position in the periodic table.
Step 6: Calculate formal charges.
To calculate formal charges, we need to compare the number of valence electrons each atom has in its neutral state (as in its column in the periodic table) with the number of electrons it actually has in the Lewis structure. A formal charge is calculated using the formula: Formal Charge = Valence Electrons - Number of Non-Bonded Electrons - 0.5 * Number of Bonded Electrons. The goal is to minimize formal charges or have them equal zero if possible.
By following these steps, a possible Lewis structure for SO2, in which all atoms obey the octet rule, and formal charges are shown, is as follows:
O
╱
O = S = O
╲
In this structure, the Sulfur (S) atom has eight electrons around it, while each Oxygen (O) atom has six electrons. The formal charges on each atom are as follows:
- Sulfur (S): 6 - 0 - 4 = +2
- Oxygen (O) (on the left): 6 - 4 - 0.5 * 4 = 0
- Oxygen (O) (on the right): 6 - 4 - 0.5 * 4 = 0
Therefore, this Lewis structure satisfies the octet rule, and the formal charges on each atom are as shown.