Quiz is "closed book" except for PT & calculator (although the calculator really isn't needed for this particular quiz). If a question requests an explanation, there may be no credit unless you have provided an explanation.

In questions #1-2, letters such as Q, R etc refer to imaginary elements. This lets us work out some of the ideas of molecular shape without being biased by knowledge of specific elements. However, H is really hydrogen. For simplicity in #1-2, use only single bonds.

1. In general, the shape of a triatomic molecule is either "linear" or "bent".
a. Draw Lewis formulas for QH₂, a linear molecule, and for RH₂, a bent molecule. For R, assume that it satisfies the octet rule.
b. What is the "electron geometry" of each of these?
c. What is the key difference that determines whether a triatomic molecule is linear or bent?
d. What would be different in any of the above parts if H were replaced by a halogen, such as Cl?
e. Give an example of a real element that would behave like Q. like R. Explain.
f. Give an example of real molecules QH₂ and RH₂.

2. The general idea of this question is to follow the same issues as in #1, but now with tetratomic molecules -- with three atoms attached to a central atom. That is, these are TH₃.
a. How many shapes are possible for molecules of the general type TH₃? (Do not exceed an octet around the central atom.) For each...
- Draw the Lewis structure.
- Give the electron geometry.
- Give the molecular shape.
- Give an example of a real element that would behave like the central atom you show.
b. What is the key difference between your various structures, in how various tetratomic molecules have different shape?