Smells Unit
Investigation IV:
Molecules in Action
Lesson 1: Breaking Up Is Hard to Do??
Lesson 2: How Does the Nose Know?
Lesson 3: Attractive Molecules
Lesson 4: Polar Bears and Penguins
Lesson 5: Thinking (Electro)Negatively
Lesson 6: I Can Relate
Lesson 7: Sniffing It Out . . .
Lesson 8: Take a Deep Breath
Smells Unit – Investigation IV
Lesson 1:
Breaking Up Is Hard to
Do??
ChemCatalyst
• Which drawing best represents what
you think is going on with the
molecules in the smell vials? Explain
your reasoning. (Pay attention to the
key.)
Key
Molecules
C, H, and O
atoms
© 2004 Key Curriculum Press.
Unit 2 • Investigation IV
The Big Question
• Do molecules break apart into atoms
when they escape from the smell vial
or do they stay together as molecules?
© 2004 Key Curriculum Press.
Unit 2 • Investigation IV
You will be able to:
• Explain smelling in the context of
phase change.
© 2004 Key Curriculum Press.
Unit 2 • Investigation IV
Notes
C4H8O2
H
H
H
H
O
C
C
C
C O
H
H
H
Vial G
butyric acid
putrid
H
H
H O
H
H
C
C
C
H
H
H
C O
H
Vial H
ethyl acetate
sweet
© 2004 Key Curriculum Press.
Unit 2 • Investigation IV
Activity
Purpose: Your goal in this activity is to
determine which picture; 1, 2, 3, or 4, is
the best representation of what is going
on with the molecules in Smell Vials G
and H.
Key
Molecules
C, H, and O
atoms
(cont.)
© 2004 Key Curriculum Press.
Unit 2 • Investigation IV
(cont.)
Picture
Does the
Does the picture
picture show show why G and
why G and H H have different
smell
properties as
different?
liquids?
Either support or
criticize this picture
as a good
representation for
what happens in
the smell vials.
1
2
3
4
© 2004 Key Curriculum Press.
Unit 2 • Investigation IV
Making Sense
• Based on this activity, do you think the
substances that you smell are staying
together as intact molecules or
breaking apart into individual atoms?
Explain your thinking.
© 2004 Key Curriculum Press.
Unit 2 • Investigation IV
Notes
• Any time a substance goes from one
state of matter (solid, liquid or gas) to
another state of matter, it is called a
phase change.
• Molecules are stable when they
remain together even when
undergoing a phase change.
© 2004 Key Curriculum Press.
Unit 2 • Investigation IV
Check-In
• Examine the following drawing and
pick the best explanation from the two
below.
© 2004 Key Curriculum Press.
Unit 2 • Investigation IV
Wrap-Up
• The idea that molecules remain
together as units explains why
molecules with the same molecular
formula can have different properties
such as smell.
• Molecules undergoing a phase change
do not break apart.
• Molecules are collections of atoms that
satisfy the octet rule; as such they are
very stable.
© 2004 Key Curriculum Press.
Unit 2 • Investigation IV
Smells Unit – Investigation IV
Lesson 2:
How Does the Nose
Know?
ChemCatalyst
• How do you think your nose detects a
smell?
© 2004 Key Curriculum Press.
Unit 2 • Investigation IV
The Big Question
• How does our nose detect different
smells?
© 2004 Key Curriculum Press.
Unit 2 • Investigation IV
You will be able to:
• Understand how a molecule is
detected by the nose.
© 2004 Key Curriculum Press.
Unit 2 • Investigation IV
Activity
Purpose: To design a model that
explains how molecules are detected in
the nose.
© 2004 Key Curriculum Press.
Unit 2 • Investigation IV
Making Sense
• No Making Sense question.
© 2004 Key Curriculum Press.
Unit 2 • Investigation IV
Notes
• A receptor site is a tiny physiological
structure made up of large, complex protein
molecules that fold to form a specific
shape. Molecules with matching shapes fit
inside these structures. When molecules
attach to receptor sites they stimulate
nerves to send a signal to the brain.
© 2004 Key Curriculum Press.
Unit 2 • Investigation IV
Check-In
One of the molecules that makes coffee
smell is 2-furylmethanethiol:
O
H C
C
H
H H
C H
C
S
C
H
• Write down everything you know about
how this molecule is detected by the
nose.
• Draw a possible receptor site for this
molecule.
© 2004 Key Curriculum Press.
Unit 2 • Investigation IV
Wrap-Up
• The currently accepted model for smell
describes smell molecules landing in
receptor sites that fit or "receive" the
shape of the smell molecules.
• In the receptor site model each
receptor site has a specific shape,
which corresponds to the shape of just
a few smell molecules.
© 2004 Key Curriculum Press.
Unit 2 • Investigation IV
Smells Unit – Investigation IV
Lesson 3:
Attractive Molecules
ChemCatalyst
• If a molecule fits into a receptor site in the
nose, it seems as if it should smell. Yet
most of the molecules that make up the
air do not have a smell. What do you
think is going on?
Smells
Smells
Doesn’t
smell?
Here are some of the gases in air: O2 (oxygen), N2
(nitrogen), CO2 (carbon dioxide), Ar (argon).
© 2004 Key Curriculum Press.
Unit 2 • Investigation IV
The Big Question
• In what ways do molecules interact
with each other?
© 2004 Key Curriculum Press.
Unit 2 • Investigation IV
You will be able to:
• Describe a polar molecule.
© 2004 Key Curriculum Press.
Unit 2 • Investigation IV
Activity
Purpose: In this lesson, you observe the
response of certain liquids to a charged
wand and the behavior of the same
liquids as droplets. These activities give
you information about possible
interactions between molecules. This is a
three-part activity.
(cont.)
© 2004 Key Curriculum Press.
Unit 2 • Investigation IV
(cont.)
(cont.)
© 2004 Key Curriculum Press.
Unit 2 • Investigation IV
(cont.)
Molecule
Results of
charged wand test
Molecule
water
attracted
isopropanol
acetic acid
Results of
charged wand test
hexane
© 2004 Key Curriculum Press.
Unit 2 • Investigation IV
Making Sense
• If water molecules are carrying a partial
charge, as shown in the following
picture, how do you think a group of
water molecules would behave towards
each other? Draw a picture of several
water molecules interacting, to illustrate
your thinking.
© 2004 Key Curriculum Press.
Unit 2 • Investigation IV
Notes
• Some molecules have a slight charge on
opposite ends of the molecule. Molecules
that have partial charges are called
polar molecules. One end of the
molecule has a partial negative charge
and the other end of the molecule has a
partial positive charge.
© 2004 Key Curriculum Press.
Unit 2 • Investigation IV
Notes
• The charged wand shows us that the
molecules in certain liquids (polar liquids)
orient themselves in response to an
electrostatic charge in their vicinity. This
causes the liquid to move in the direction of
the charge.
(cont.)
© 2004 Key Curriculum Press.
Unit 2 • Investigation IV
Notes (cont.)
• Hexane was not attracted to the
charged wand. So it would seem
reasonable to suggest that different
ends of the molecule do not have
opposite partial charges. Molecules
such as this are called nonpolar
molecules.
(cont.)
© 2004 Key Curriculum Press.
Unit 2 • Investigation IV
Notes (cont.)
• The attraction that happens between
individual polar molecules is called an
intermolecular interaction or an
intermolecular attraction.
© 2004 Key Curriculum Press.
Unit 2 • Investigation IV
Check-In
• Acetone is polar. Name two other
things that are probably true about
acetone.
© 2004 Key Curriculum Press.
Unit 2 • Investigation IV
Wrap-Up
• Polar molecules have partial charges
on parts of the molecule.
• Polar molecules are attracted to a
charge.
• Polar molecules are attracted to each
other. These intermolecular
interactions account for many
observable properties.
© 2004 Key Curriculum Press.
Unit 2 • Investigation IV
Smells Unit – Investigation IV
Lesson 4:
Polar Bears and
Penguins
ChemCatalyst
Consider the following illustration:
(cont.)
© 2004 Key Curriculum Press.
Unit 2 • Investigation IV
(cont.)
• Draw the Lewis dot structure for HCl.
• If the penguin represents a hydrogen
atom and the polar bear represents a
chlorine atom, what does the ice
cream represent in the drawing? What
do you think the picture is trying to
illustrate?
• Would HCl be attracted to the charge
wand? Explain your thinking.
© 2004 Key Curriculum Press.
Unit 2 • Investigation IV
The Big Question
• How can we explain partial charges on
molecules?
© 2004 Key Curriculum Press.
Unit 2 • Investigation IV
You will be able to:
• Recognize and explain a polar bond.
© 2004 Key Curriculum Press.
Unit 2 • Investigation IV
Activity
Purpose: In this lesson you will be
exploring polarity and bonding between
atoms in greater detail. A comic book will
provide new information about these
topics and will introduce you to the
concept of electronegativity, which helps
us to understand partial charges.
© 2004 Key Curriculum Press.
Unit 2 • Investigation IV
Making Sense
• What does electronegativity have to do
with polarity?
© 2004 Key Curriculum Press.
Unit 2 • Investigation IV
Notes
• This tendency of an atom to attract
electrons shared between two atoms is
called electronegativity.
• An atom that strongly attracts the
shared electrons is considered highly
electronegative. The atom with lower
electronegativity will end up with a
partial positive charge on it. The result
is a polar bond.
© 2004 Key Curriculum Press.
Unit 2 • Investigation IV
Notes (cont.)
• Chemists have a specific name for a
molecule that has two poles—it is
called a dipole. ("Di" means two.)
(cont.)
© 2004 Key Curriculum Press.
Unit 2 • Investigation IV
Notes (cont.)


• This illustration also uses a crossed arrow
to show the direction of the dipole in
HCl. The crossed end of the arrow
indicates the positive (+) end of the polar
bond and the arrow points in the direction
of the negative (-) end.
© 2004 Key Curriculum Press.
Unit 2 • Investigation IV
Notes (cont.)
• Polar molecules are also called dipoles.
The prefix di- means two. A dipole is a
molecule with two partially charged
ends, or poles. Chemists refer to polar
molecules as dipoles and they also say
that molecules with polar bonds have
dipoles. This nomenclature can be a bit
confusing with two related meanings for
two closely-related meanings for the
same word.
© 2004 Key Curriculum Press.
Unit 2 • Investigation IV
Notes (cont.)
• Nonpolar covalent bonds are the only
bonds in which the electrons are truly shared
equally.
• If the electronegativities between two atoms
are even slightly different, they form what is
called a polar covalent bond.
• When the electronegativities between two
atoms are greatly different, the bond is called
an ionic bond. In the case of an ionic bond
the electron of one atom is completely given
up to the other atom.
© 2004 Key Curriculum Press.
Unit 2 • Investigation IV
Notes (cont.)
O
C
O
© 2004 Key Curriculum Press.
Unit 2 • Investigation IV
Check-In
• Is the bond between these atoms
polar? Explain your reasoning.
• How would the atoms be portrayed in
the comic book—as polar bears,
penguins, or both? Explain.
© 2004 Key Curriculum Press.
Unit 2 • Investigation IV
Wrap-Up
• Anytime there are two different types of
atoms sharing electrons, there will be a
partial negative charge on one atom and
a partial positive charge on the other
atom.
• Electronegativity measures the tendency
of an atom to attract the electrons in a
bond.
(cont.)
© 2004 Key Curriculum Press.
Unit 2 • Investigation IV
(cont.)
• The bonds are labeled nonpolar
covalent, polar covalent, and ionic as
the difference in electronegativity
between the two atoms in the bond
increases.
© 2004 Key Curriculum Press.
Unit 2 • Investigation IV
Smells Unit – Investigation IV
Lesson 5:
Thinking
(Electro)Negatively
ChemCatalyst
• Explain how the illustration and the
table might relate to each other.
© 2004 Key Curriculum Press.
Unit 2 • Investigation IV
The Big Question
• How does electronegativity relate to
polarity and bonding?
© 2004 Key Curriculum Press.
Unit 2 • Investigation IV
You will be able to:
• Determine whether a bond is polar,
nonpolar, or ionic.
© 2004 Key Curriculum Press.
Unit 2 • Investigation IV
Activity
Purpose: This lesson explores
electronegativity in a quantitative
fashion—that is, it applies numbers to
our investigation of polarity. Using the
electronegativity scale it is possible to
compare atoms and find out which ones
will attract electrons more strongly in a
bond.
(cont.)
© 2004 Key Curriculum Press.
Unit 2 • Investigation IV
(cont.)
© 2004 Key Curriculum Press.
Unit 2 • Investigation IV
Making Sense
• Explain how you would determine both
the direction and degree of polarity of a
bond between two different atoms using
the electronegativity scale.
(cont.)
© 2004 Key Curriculum Press.
Unit 2 • Investigation IV
(cont.)
© 2004 Key Curriculum Press.
Unit 2 • Investigation IV
Notes
• A molecule made from only two atoms
is called a diatomic molecule.
(cont.)
© 2004 Key Curriculum Press.
Unit 2 • Investigation IV
Notes (cont.)
• Nonpolar covalent bonds are really
the only true covalent bonds.
• If the electronegativities between two
atoms are even slightly different they
form what is called a polar covalent
bond. In polar covalent bonds the
bonding electrons are located closer to
the more electronegative atom.
(cont.)
© 2004 Key Curriculum Press.
Unit 2 • Investigation IV
Notes (cont.)
• When the electronegativities between
two atoms are greatly different the
bond is called an ionic bond. In the
case of an ionic bond the electron of
one atom is completely given up to the
other atom.
© 2004 Key Curriculum Press.
Unit 2 • Investigation IV
Check-In
• To what degree do the K and Cl atoms
in KCl, potassium chloride, share
electrons? Is the bond in potassium
chloride nonpolar, polar, or ionic?
Explain your thinking.
© 2004 Key Curriculum Press.
Unit 2 • Investigation IV
Wrap-Up
• Electronegativity measures how strongly
an atom will attract shared electrons.
• The greater the difference in
electronegativity between two atoms, the
more polar the bond will be.
• In the case of an ionic bond, the
electronegativities between two atoms are
so greatly different that the electron(s) of
one atom is(are) completely given up to
the other atom.
© 2004 Key Curriculum Press.
Unit 2 • Investigation IV
Smells Unit – Investigation IV
Lesson 6:
I Can Relate
ChemCatalyst
• HCl (hydrogen chloride) and NH3
(ammonia) smell and they dissolve
easily in water. O2, N2, and CH4
(oxygen, nitrogen, and methane) do
not smell and they do not dissolve
easily in water. How can you explain
these differences?
© 2004 Key Curriculum Press.
Unit 2 • Investigation IV
The Big Question
• How does polarity help to explain what
is happening between smell molecules
and the nose?
© 2004 Key Curriculum Press.
Unit 2 • Investigation IV
You will be able to:
• Use polarity to predict whether a
molecule will have a smell.
© 2004 Key Curriculum Press.
Unit 2 • Investigation IV
Notes
• Water molecules in liquid water orient so
that the H atom from one water
molecule is pointed toward the O atom
of another water molecule. This type of
interaction with an H atom between two
electronegative atoms on two different
molecules is called a hydrogen bond.
© 2004 Key Curriculum Press.
Unit 2 • Investigation IV
Activity
Purpose: The goal of this lesson is to
give you practice in determining the
polarity of small molecules with more
than two atoms. In addition, you will
explore how polarity and
electronegativity relate back to smell.
(cont.)
© 2004 Key Curriculum Press.
Unit 2 • Investigation IV
(cont.)
(cont.)
© 2004 Key Curriculum Press.
Unit 2 • Investigation IV
(cont.)
HCl
NH3
H2S
CH2O
CClF3
CH4O
CF4
(cont.)
© 2004 Key Curriculum Press.
Unit 2 • Investigation IV
(cont.)
Molecule Has a smell? Molecule Has a smell?
N2
No
NH3
Yes
PH3
Yes
HBr
Yes
CH4
No
CO2
No
H2Se
Yes
AsH3
Yes
© 2004 Key Curriculum Press.
Unit 2 • Investigation IV
Making Sense
• Explain why polarity might be an
important concept to understand when
trying to figure out the chemistry of
smell.
© 2004 Key Curriculum Press.
Unit 2 • Investigation IV
Notes
(cont.)
© 2004 Key Curriculum Press.
Unit 2 • Investigation IV
Notes (cont.)
N
O
N
O
C
O
F
H
H
C
H
O
H
F
C
F
F
Nonpolar molecules
(cont.)
© 2004 Key Curriculum Press.
Unit 2 • Investigation IV
Notes (cont.)
H
P
H
N
H
H
H
H
Se
H
H
Cl
H
Polar molecules
(cont.)
© 2004 Key Curriculum Press.
Unit 2 • Investigation IV
Notes (cont.)
• Polar molecules tend to dissolve more
easily in other polar molecules
because of the intermolecular forces
between the molecules. Nonpolar
molecules tend not to dissolve in polar
substances.
© 2004 Key Curriculum Press.
Unit 2 • Investigation IV
Check-In
• Due to differences in electronegativity,
we expect HCN, hydrogen cyanide, to
be polar. Since water is polar as well,
which way do you think water and
hydrogen cyanide molecules would
orient with each other? Explain your
reasoning.
(cont.)
© 2004 Key Curriculum Press.
Unit 2 • Investigation IV
(cont.)
• Do you think HCN will have a smell?
Explain.
© 2004 Key Curriculum Press.
Unit 2 • Investigation IV
Wrap-Up
• Differences in electronegativity values
can be used to determine the direction
of the dipole for an entire molecule.
• The polarity or nonpolarity of a
molecule is responsible for a great
many of its observable properties.
• Small polar molecules smell. Small
nonpolar molecules do not smell.
© 2004 Key Curriculum Press.
Unit 2 • Investigation IV
Smells Unit – Investigation IV
Lesson 7:
Sniffing It Out . . .
ChemCatalyst
• If you place an open perfume bottle
and a piece of paper in a sunny
window, the aroma of the perfume will
soon fill the air, but you won’t smell the
paper at all. Explain what is going on.
What is the heat from the sun doing to
the perfume to increase its smell?
© 2004 Key Curriculum Press.
Unit 2 • Investigation IV
The Big Question
• How can we apply what we’ve learned
about smell to our daily lives?
© 2004 Key Curriculum Press.
Unit 2 • Investigation IV
You will be able to:
• Describe the physical and chemical
factors that determine whether on not
a type of molecule will smell.
© 2004 Key Curriculum Press.
Unit 2 • Investigation IV
Activity
Purpose: This lesson wraps up the
Smells Unit by introducing data showing
that size of molecules, type of bonding,
and phase, together with polarity all
determine if a substance will have a
smell.
(cont.)
© 2004 Key Curriculum Press.
Unit 2 • Investigation IV
(cont.)
Substance type
Examples
Smell?
Phase
Bonding
Size
Name
Formula
Molecular
Nonpolar
covalent
Small
molecules
nitrogen
oxygen
carbon dioxide
methane
N2
O2
CO2
CH4
no
gas
Molecular
Polar
covalent
Small
molecules
hydrogen chloride
hydrogen sulfide
ammonia
fluoromethane
HCl
H2S
NH3
CH3F
yes
gas
Molecular
Polar and
nonpolar
covalent
Medium
sized
molecules
octane
geraniol
carvone
amylproprionate
C8H18
C10H18O
C10H14O
C8H16O2
yes
liquid
(cont.)
© 2004 Key Curriculum Press.
Unit 2 • Investigation IV
(cont.)
Substance type
Examples
Bonding
Size
Name
Formula
Molecular
Covalent
Large
molecules
1-triacontyl palmitate
(beeswax)
polystyrene
(styrofoam)
cellulose
C46H92O2
C8000H8000
Ionic
Metals
bonded to
nonmetals
sodium chloride
(table salt)
calcium oxide (lime)
calcium carbonate
(chalk)
Metallic
Elemental
metals
gold
copper
aluminum
Smell?
Phase
no
solid
no
solid
no
solid
C1800H300O15
00
NaCl
CaO
CaCO3
Au
Cu
Al
(cont.)
© 2004 Key Curriculum Press.
Unit 2 • Investigation IV
Will
Smell
Won’t
Smell
Example
Chemistry Reasoning
A brass doorknob
Cu, Zn
Sweaty socks
hexanoic acid,
C6H12O2
Epsom salts
magnesium
sulfate, MgSO4
Anisyl alcohol in
laundry soap
C8H10O2
This is a solid substance made of
molecules that are so large they will not
go into the gas phase under normal
conditions.
X
Sunflower oil
C21H38O5
© 2004 Key Curriculum Press.
Unit 2 • Investigation IV
Making Sense
• What general statement(s) can you
make about whether a substance will
have a smell? (For example: Small
polar molecules have a smell.)
© 2004 Key Curriculum Press.
Unit 2 • Investigation IV
Notes
General Ideas about smell:
• Polarity determines the smell of small
molecules.
• Small polar molecules smell.
• Small nonpolar molecules do not smell.
• Polarity does not determine smell in the
cases of medium and large molecules.
(cont.)
© 2004 Key Curriculum Press.
Unit 2 • Investigation IV
Notes (cont.)
• Many solids do not evaporate into
gases easily, therefore, solids tend not
to smell unless they can become
volatile (components of a chocolate
bar.)
• Nonmolecular solids (ionic and metallic
solids) do not smell.
• Medium-sized molecules all seem to
smell.
(cont.)
© 2004 Key Curriculum Press.
Unit 2 • Investigation IV
Notes (cont.)
• Shape and functional group help
determine the smell of medium-sized
molecules.
• Large molecules do not smell. They
are too big and bulky to become gases
and move into the nose.
• Ionic compounds do not smell – they
do not enter the gas phase and travel
into the nose like covalently bonded
(cont.)
molecules.
© 2004 Key Curriculum Press.
Unit 2 • Investigation IV
Notes (cont.)
• According to the table, molecules that are
gases at ordinary temperatures are
composed of very small molecules or of
single atoms (such as argon or neon). This
is true.
• According to the table liquids seem to be
composed mostly of medium-sized
molecules. This is also a fairly consistent
generalization, although some liquids do
exist that are composed of large, heavy
(cont.)
molecules.
© 2004 Key Curriculum Press.
Unit 2 • Investigation IV
Notes (cont.)
• According to the table, solids are
composed of large molecules, ionic
compounds, or metallic substances. Of
course, we know from experience that
some solids sublimate; that is, a few
molecules go directly from the solid
phase to the gas phase, without
passing through the liquid phase.
(cont.)
© 2004 Key Curriculum Press.
Unit 2 • Investigation IV
Chemical
Name
Common
Name
Phase
Molecular
Formula
Structural Formula
H
natural
methane
gas
gas
C
CH4
H
H
H
octane
gasoline
liquid
C8H18
H
H
H
H
H H
H
H
C
C C
C C
C
C C
H
H
H
H
H
H
H
H
H
H
H
H
H
C
C
C
polystyrene styrofoam
solid
C
C
(C8H8)n
H
etc....
CH2
H
C
C
CH2
C
H
C
H
C
CH2
etc....
H
C
C
H
H
C
C
H
H
Repeating….
© 2004 Key Curriculum Press.
Unit 2 • Investigation IV
Notes (cont.)
• One of the most important facts you
can remember in your study of smell
chemistry is that a molecule must be in
the gas phase in order to be smelled.
© 2004 Key Curriculum Press.
Unit 2 • Investigation IV
Check-In
• Which of the following molecules will
smell? Explain your reasoning.
Molecule
Structure
Phase
CaCl2
calcium chloride
Cl– Ca2+ Cl–
(repeating throughout the solid in 3 dimensions)
O
solid
H
C
C
H
C
vanillin
H
C
C
H
C
C
O
O
H
HCN
hydrogen cyanide
liquid
H
H
C
C
H
H
N
gas
© 2004 Key Curriculum Press.
Unit 2 • Investigation IV
Wrap-Up
• Small molecules smell if they are polar.
• Medium-sized molecules tend to smell,
whether they are polar or not.
• The smells of medium-sized molecules
can be predicted by looking at shape
and functional group.
(cont.)
© 2004 Key Curriculum Press.
Unit 2 • Investigation IV
(cont.)
• Very large molecules do not smell because
they do not evaporate and enter the nose.
• Nonmolecular solids (e.g., salts, metals)
do not smell because they do not
evaporate.
• Water is an exception to these
generalizations. Humans do not smell
water, but conceivably other mammals do.
© 2004 Key Curriculum Press.
Unit 2 • Investigation IV
Smells Unit – Investigation IV
Lesson 8:
Take a Deep Breath
ChemCatalyst
• Name three items that might be on an
exam covering the entire Smells Unit.
© 2004 Key Curriculum Press.
Unit 2 • Investigation IV
The Big Question
• How well can we predict a molecule's
smell, and what factors do we need to
consider?
© 2004 Key Curriculum Press.
Unit 2 • Investigation IV
You will be able to:
• Switch between the structural formula,
Lewis dot structure, and threedimensional shape of a molecule, and
determine the polarity.
© 2004 Key Curriculum Press.
Unit 2 • Investigation IV
Activity
Purpose: The goal of this lesson is to
integrate your learning about smell
chemistry and to review the entire unit.
(cont.)
© 2004 Key Curriculum Press.
Unit 2 • Investigation IV
(cont.)
a) Structural
formulas…
b) Properties….
c) Reasoning…
(cont.)
© 2004 Key Curriculum Press.
Unit 2 • Investigation IV
(cont.)
a) Structural
formulas…
b) Properties….
c) Reasoning…
(cont.)
© 2004 Key Curriculum Press.
Unit 2 • Investigation IV
(cont.)
H
H
O
C C
H C
C C O C H
C C
H
H
H
O
H
© 2004 Key Curriculum Press.
Unit 2 • Investigation IV
Making Sense
H
H
C
H
O
H
H
C
C
H
Has a smell
Polar
Smallish molecule
Polar
Shape is non-symmetrical
H
C
O
H
Has a smell
Polar
Smallish molecule
Polar
Shape is non-symmetrical
(cont.)
© 2004 Key Curriculum Press.
Unit 2 • Investigation IV
(cont.)
H
H
H H H
C C C C
H
O
H H H
H
H
H
H
C
C
H
H
O
H
H
C
C
H
H
H
H
H
H
C
C
O
C
H H C
H
H
H
H
H
Has a smell
polar
Has a smell
polar
Has a smell
polar
Non-symmetrical
molecule
Medium-sized
Alcohol
Non-symmetrical
molecule
Medium-sized
Ether
Non-symmetrical
molecule
Medium-sized
Ether
(Note: The flat
drawing looks
symmetrical but the
geometry around the
O atom is bent.)
© 2004 Key Curriculum Press.
Unit 2 • Investigation IV
(cont.)
Other possible structural formulas
H
H
H
H
H
C C
C
C
H
H
O
H
H
H
C
H
H
H
H
C
C
H
H
H
H
C
H
O
H
H
O
H
H
C
C
H
H
C
H
C
H
H
H
H
H
H
C
C
C
H
H
H
H
O
C
H
H
H
H
(cont.)
© 2004 Key Curriculum Press.
Unit 2 • Investigation IV
(cont.)
H
H
O
C C
H C
C C O C H
C C
H
H
H
O
H
© 2004 Key Curriculum Press.
Unit 2 • Investigation IV
Check-In
• Predict the smell for each of the
following molecules and explain your
reasoning.
H H H H H H H H H O
H
decanoic acid
C
C
H C C C C C C C C C C O H
H H H H H H H H H
H
O
H
H
H
H
dimethyl ether
© 2004 Key Curriculum Press.
Unit 2 • Investigation IV
Wrap-Up
• No Wrap-Up
© 2004 Key Curriculum Press.
Unit 2 • Investigation IV