The Physical Properties of Matter
Properties of Materials
Science Begins with Observation &
Classification
„
Chapter 12
„
„
What is “stuff”
stuff” made of?
How does science work?
Melting point
Copper
Observation is first step in scientific method
Group similar observations
Develop hypotheses & models as
explanations
Please pick up a “slide”
slide” (diffraction grating) as you come
in. Return it at the end of class.
Properties of Materials
°C
BOILING
TEMPERATURE
°C
(under 1 atm pressure)
State
At
Room
Temperature
doesn’t form solid
except under high
pressure!
-269
Gas
MELTING
TEMPERATURE
-117
78.5
1065
2807
Helium
-259
-253
Neon
-249
-246
Nitrogen
-210
-196
Table salt
801
1413
0
100
‰
-259
-253
Gas
Neon
-249
-246
Gas
Nitrogen
-210
-196
Gas
0
100
Liquid
‰
‰
Ethanol
-117
78.5
Liquid
Table salt
801
1413
Solid
Copper
1083
2567
Solid
Gold
1065
2807
Solid
4
„
3
Solids
„
Four ways to apply force
‰
Hydrogen
Water
„
-269
Hydrogen
2
Response to Force
2567
Ethanol
Water
Consider
The State
Of Material
At Room
Temperature
Boiling point
Gold
Helium
How do scientists approach problems?
1
1083
Compression
Tension
Shear
Torsion
„
Maintain a constant
shape
Support all 4 types of
deformation
States of matter defined in part by how matter
responds to force
5
6
1
Liquids
„
„
Gases
Fluid
‰ Assume shape of container but do
not expand to fill volume
Support compression, tension but not
shear, torsion
„
„
Plasmas
Fluid
‰ Assume shape of
container & expand
to fill
Support compression
but not any of the
others
„
„
7
Melting point
Copper
8
1083
Range of Melting
Temps?
Range of Boiling
Temp?
Table Salt
Copper
Gold
2567
Melting Temperature
Ethanol
-117
78.5
Gold
1065
2807
Helium
Lowest Boiling
Temp?
Groupings
Boiling point
Highest Boiling
Temp?
Lowest Melting
Temp?
9
Graphical representations of the same data
Properties of Materials
Highest Melting
Temp?
Similar to gas, but
individual particles are
charged
Most common state in
the universe
-269
Hydrogen
-259
-253
Neon
-249
-246
Nitrogen
-210
-196
Table salt
801
1413
0
100
Water
-200
0
200
400
600
Hydrogen
Water
Neon Ethanol
Nitrogen
800
1000
Gold
Table Salt Copper
Boiling Temperature
-500
10
0
500
Nitrogen
Water
Neon
Ethanol
Hydrogen
Helium
1000
1500
Table Salt
2000
2500
High Melting
High Boiling
Ethanol
Water
Helium
Hydrogen
Neon
Nitrogen
Intermediate
In Melting & Boiling
3000
Copper Gold
11
Low Melting
Low Boiling
12
2
Testing Hypothesis –
Look for Mathematical Relationships
From the previous observations, which
would be a reasonable hypothesis?
1.
2.
3.
The melting and boiling points of a
substance are related (show a
correlation).
High melting point substances boil at a
low temperature.
There is no correlation between
melting and boiling points.
13
Common Ways of Classifying Matter
14
„
„
„
„
Response to force
Electrical properties
State
Density
Color
„
DENSITY
g / cm3
Density = mass/volume.
Changes of state usually involve abrupt changes in
density.
Solid
Helium
What do these mean?
Are some or all of them related?
16
15
Properties of Materials –
Densities of different states
Density
„
„
Testing Hypothesis –
Look at Additional Substances
17
Liquid
Gas
0.122
0.00018
Hydrogen
0.078
0.071
0.0001
Neon
1.54*
1.21
0.00082
Nitrogen
Water
1.09
0.90 (0ºC)
0.81
1.00
0.0013
0.0006
Ethanol
1.3
0.80
0.0020
Table salt
Copper
Gold
2.2
8.9
19.3
Not available
Not available
Not available
Not available
Not available
Not available
* Error in Table in the text.
Sequence of densities?
18
3
For almost all materials, density
follows the order
A.
B.
C.
D.
Changes of State
Gas < solid < liquid
Gas < liquid < solid
Solid < liquid < gas
Liquid < solid < gas
„
„
Color
State depends on temperature (and pressure).
Different materials change state at different
temperatures.
Material
Melting temp
Boiling temp
Ionization
temp
Nitrogen
-210
-196
~+1000
Water
0
100
breakdown
Iron
1535
3000
~+4000
Solid
Liquid
Gas
„
A rainbow or spectrum of all colors is called
continuous.
„
If only some portions of light are present the
spectrum is called discrete or emission-line
„
20
Color
22
White light contains
all colors. Materials
take on the color that
they reflect the most.
Is there a trend to
color related to our
three categories?
Plasma
19
Color
„
21
Electrical Properties
„
If a continuous spectrum is missing some
portions of light it is called an absorption line
spectrum.
„
Each different material has a unique spectrum
– like a fingerprint.
„
23
Conductors transmit electrical charge freely
24
4
Electrical Properties
„
„
„
Why?
Insulators do not conduct (glass, ceramic,
wood, plastic, rubber).
Semiconductors are man-made things that
conduct under some conditions and not
under others (transistors, diodes).
Ionic conductors conduct when they are a
liquid or dissolved in a liquid but not as a
solid (salt).
„
25
We need to build some hypotheses and form
some models!
26
5