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Investigation 7B
The Geometry of Molecules
2 Investigation 7B: The Geometry of Molecules
H O HStructural diagram:
This molecule looks like it should be “straight” or linear…
… but it really has a bent shape
Why isn’t water a linear molecule?
3 Investigation 7B: The Geometry of Molecules
H O HStructural diagram:
This molecule looks like it should be “straight” or linear…
… but it really has a bent shape
Lone electron pairs on the oxygen atom take up space too!
4 Investigation 7B: The Geometry of Molecules
Build these five molecules.
Compounds made of only 2 atoms are typically bent in shape.
Compounds made of only 3 atoms are typically linear in shape.
Part 1: Linear and bent molecules
5 Investigation 7B: The Geometry of Molecules
a. Name two other elements which would likely form a bent molecule when bound with two hydrogen atoms.
b. Create two other linear molecules. What elements do they contain?
Part 1: Linear and bent molecules
6 Investigation 7B: The Geometry of Molecules
Real molecules are not flat but have 3-dimensional forms.
7 Investigation 7B: The Geometry of Molecules
Build the following molecules.
Do these two molecules have the same shape?
Part 2: Trigonal planar and trigonal molecules
8 Investigation 7B: The Geometry of Molecules
a. Which of these molecules has a trigonal pyramidal shape? Can you explain why?
b. Which of these molecules has a trigonal planar shape? Can you explain why?
c. Name another element which would combine with three hydrogen atoms to make a trigonal molecule.
Part 2: Trigonal planar and trigonal molecules
9 Investigation 7B: The Geometry of Molecules
Part 2: Trigonal planar and trigonal molecules
10 Investigation 7B: The Geometry of Molecules
Carbon
1s22s22p2
4 valence electrons
Lewis dot diagram for carbon
Carbon can donate 4 electrons…
11 Investigation 7B: The Geometry of Molecules
1s22s22p2
4 valence electrons
Lewis dot diagram for carbon
Carbon can donate 4 electrons…… or gain 4 electrons.
Carbon
12 Investigation 7B: The Geometry of Molecules
Build the following molecules.
Part 3: Molecules with hydrogen and carbon
13 Investigation 7B: The Geometry of Molecules
a. Which of these molecules (if any) is planar?
b. Which of these molecules (if any) is linear?
c. Which of these molecules (if any) is tetrahedral? A tetrahedron is a pyramid with four triangular sides.
d. Which of these molecules (if any) is a ring?
Part 3: Molecules with hydrogen and carbon
14 Investigation 7B: The Geometry of Molecules
Many important molecules contain nitrogen and oxygen atoms.
Part 4: Molecules with nitrogen and oxygen
15 Investigation 7B: The Geometry of Molecules
Many important molecules contain nitrogen and oxygen atoms.
a. Name two instances in these molecules where you find a
tetragonal form. What element is central to this form?
b. Name two instances in these molecules where you find a trigonal
form. What element is central to this form?
Part 4: Molecules with nitrogen and oxygen
16 Investigation 7B: The Geometry of Molecules
Many important molecules contain nitrogen and oxygen atoms.
c. Describe what is similar between methanol (wood alcohol) and
ethanol (grain alcohol).
Part 4: Molecules with nitrogen and oxygen
17 Investigation 7B: The Geometry of Molecules
Many important molecules contain nitrogen and oxygen atoms.
d. Amines are nitrogen-bearing compounds, often with very strong
odors. Which of these compounds are amines?
Part 4: Molecules with nitrogen and oxygen
18 Investigation 7B: The Geometry of Molecules
Ascorbic acid(vitamin C)
The function of a molecule depends on its 3-dimensional shape.
Acetaminophen(active ingredient in Tylenol)
