Question 4.25 Part A

[Haison Nguyen 1I]

For part A we were suppose to write the lewis structure of CCl2H2 and determine if it was nonpolar or polar. Based on the structure, it would make sense that it's polar since both Cls are next to each other and pulling on the electrons of C. But how are we suppose to know the structure of the molecule? I initially put the Cls opposite of each other so wouldn't that cancel out and be nonpolar?

[kendallbottrell]

You have to figure out the 3-D structure and picture it to realize the orientation of the Cl atoms. Even if you do put them opposite of each other on the Lewis structure, on the VSEPR model, the Cl atoms would not be opposite of each other, and therefore not cancel.

[Isabelle De Rego 1A]

Just to elaborate, you would know that the structure is polar because it's tetrahedral. You know that its tetrahedral because there are four regions of high electron density. When you draw out the structure, the Cls will both pull away from C in the same direction.