Transcript Properties of Materials

Get the box of Stuff
Wood, steel, aluminum, melamine
Properties of Materials
Goal: Students will be able to
describe various physical
properties that materials have
Discussion
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differentiate between chemical and
physical properties
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At your tables list examples of chemical
and physical properties.
I will call on each table and make a list of
all the ones we can think of.
Chemical Properties
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how a material interacts with another
material
“social” behavior
response to other matter (or lack of
response)
reactions
Chemical Properties
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Examples:
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burning
reaction with acid
reaction with water
corrosion/rusting/oxidation
others????
Physical Properties
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characteristics it possesses by itself
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“personal” traits
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response to energy
(in and of itself)
Physical Properties
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color
size
texture
melting point
boiling point
solubility
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luster
density
magnetism
odor
viscosity
crystalline structure
Physical Properties
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Electrical properties
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conductor or insulator
Optical properties – response to light
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index of refraction – bending of light
transparent – light passes through
translucent – some light passes through but no
distinct image
opaque – no light passes through
Physical Properties
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Thermal properties – response to heat
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conductivity
specific heat – how much energy it takes to
change temperature
thermal expansion – example: iron wire
demo
Mechanical Properties
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subgroup of physical
response to force or stress
 force – a push or pull
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stress – force causing a deformation or
distortion (force per unit area)
Mechanical Properties
Examples
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workability
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malleability – can be flattened
ductility – can be drawn into wire
(stretched), bent, or extruded
Mechanical Properties
Examples
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brittleness
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breaks instead of deforming when stress is
applied
hardness
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resistance to denting or scratching
Mechanical Properties
Examples
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elasticity
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ability to return to original shape after
being deformed by stress
rubber ball or piece of elastic
plasticity
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retains new shape after being deformed by
stress
wet clay ball or piece of saran wrap
Some of the properties
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At your tables you will find some signs
with different physical properties.
Go around between tables and answer the
questions on a separate piece of paper.
Index of Refraction
Question. What two materials here have a similar index of refraction?
(the three materials are glass, HDPE, and mineral oil)
Electrical conductivity
What materials here are non-conductive electrically?
(the materials are brass, copper coated steel, wax, glass and carbon fiber)
Hardness
Which material here is the hardest?
(Pine and Melamine)
Mechanical Properties
Examples
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toughness
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ability to absorb energy
resistance to fracture
strength
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resistance to distortion by stress or force
several types: tensile, compressive,
torsional, bending, shear
Types of Stresses/Forces
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Tension
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pulling
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examples: tug-of-war, slingshot
Compression
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pushing together or squeezing
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examples: bed springs, can crusher, bench vise
straight line = elastic region
curved line = plastic region
Ceramic or
glass
stress
metal
polymer
strain
City of Materials
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http://www.cityofmaterials.com
General Classes of Materials
Polymers
Ceramics
Composites
Metals and Alloys
Metals and Alloys
Wood and Wood Products
Free write
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On a piece of paper please describe
various physical and chemical properties
that material's have. If you can include
how you could test those physical
properties.