Problem 149 - Chemistry: An Atoms-Focused Approach

Question

Use formal charges to predict whether the atoms in carbon disulfide are arranged CSS or SCS.

Step-by-Step Solution

Answer

Answer: The SCS arrangement is more likely for carbon disulfide, as it has formal charges of 0 for all atoms, making it more stable than the CSS arrangement.

Step 1: Determine the number of valence electrons for each atom

Carbon has 4 valence electrons, and sulfur has 6 valence electrons.

Step 2: Draw the Lewis structures for both CSS and SCS arrangements

In the CSS arrangement, the carbon atom is in the center and is singly bonded to each of the sulfur atoms. In this structure, there are 2 lone pairs on each sulfur atom. In the SCS arrangement, the sulfur atom is in the center and is doubly bonded to each of the carbon atoms. There are 2 lone pairs on the central sulfur atom and no lone pairs on the carbon atoms.

Step 3: Calculate formal charges for each atom in both arrangements

To calculate the formal charge of an atom, use the formula: Formal charge = Valence electrons (in atomic state) - Assigned electrons (in molecular state) For CSS arrangement: Formal charge on Carbon: 4 - (2 + 0) = 2 Formal charge on each Sulfur: 6 - (1 + 6) = -1 (each) For SCS arrangement: Formal charge on each Carbon: 4 - (0 + 4) = 0 (each) Formal charge on central Sulfur: 6 - (2 + 4) = 0

Step 4: Compare formal charges and determine the most stable arrangement

Compare the formal charges for each arrangement: CSS: Carbon (2), Sulfur (-1, -1) SCS: Carbon (0, 0), Sulfur (0) The SCS arrangement has formal charges of 0 on all atoms, which means it is more stable (lower energy) than the CSS arrangement that has formal charges of 2 for Carbon and -1 for each Sulfur. Hence, SCS is the more likely arrangement for carbon disulfide.