AP Chemistry Question of the Day --40

Welcome back to my blog. Here comes the answer to question 38 I posted yesterday. The correct answer is C. 

First let's refresh our minds with the rules of writing Lewis structures.

1. —Determine the central and terminal atoms

2. Determine the total valence electrons in molecule or ion

—3. Form single bond between atoms.

—4. Any electrons remaining are placed on terminal atoms first to meet octet rule.

—5. Form double or triple bond if the central atom has less than eight electrons. If B is the central atom, it can have less than 8 electrons. —The central atom may have more than 8 electrons only if it is in period 3-7. The max. number of electrons is 12.

From the question, it is stated that S is the central atom. The total numbers of valence electrons are 6+6+7+7=26. 6 are used to make the S-O and 2S-Cl bonds. 18 will be used to make all the terminal atoms octet. The two electrons that are left over are then placed on the central S atom. Now we count the number of electron groups around S which is 4. So The central S takes tetrahedron geometry and the bond angle would be close to 109. C is the correct answer. 

Following is the Lewis structure for SOCl2:

Following is Question 40 of the series. 

40. 

I will post the answer and explanation tomorrow. 

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