Transcript Chapter 12 - Properties of Matter

Chapter 12 - Properties of Matter
12.1 – Properties of Solids
pp. 270-275 &
17.1 Chemical Reactions
pp. 384-387
PROPERTIES OF SOLIDS
• Different kinds of matter have
different characteristics.
• Characteristics that you can observe
directly are called physical properties.
• Substances can be identified by their
physical properties.
Physical Properties
Can be observed or measured without changing
the identity of the matter
Include:
• Color
∙odor
∙mass
• Volume
∙density
∙solubility
• Malleability
∙ductility
• State of matter
• Thermal conductivity
malleability
The ability to be
pounded into thin
sheets
Example:
Aluminum can be
rolled or pounded
into sheets to
make foil
ductility
• The ability to be
drawn into a thin
wire
• Example:
copper can be
drawn into a thin
wire
Density
• Formula used to calculate density
• D=m
V
Where D = density (measured in g/cm3)
m = mass (measured in g)
And V= volume (measured in cm3)
DENSITY OF A SOLID
• Depends on two things:
–The mass of the object
–How tightly packed together the
atoms are.
TWO TYPES OF SOLID
• Crystalline solid
particles are arranged in a repeating
pattern of rows.
Ex.: diamond, ice, iron, salts, minerals,
metals
• Amorphous solid
Particles are not in any particular order
Examples include: oobleck, rubber, wax,
glass
• Tensile strength
A measure of how much stress from
pulling a material can withstand before
breaking. Brittle materials have low
tensile strength.
• Hardness
measure's a solid’s resistance to
scratching.
Ex.: MOH’S scale of hardness.
• Elasticity
• This describes a solid's ability to
be stretched and return to its
original shape.
• Brittleness- the tendency of a solid
to crack or break before stretching
very much.
Glass is a brittle material.
Physical Changes
• A change that affects
one or more physical
properties of a
substance
• Physical changes can
be undone
• Examples: freezing
water for ice cubes
• Cutting your hair
• Bending a paper clip
Chemical Properties
•
describe a substance based on its ability
to change into a NEW substance with
DIFFERENT properties
Include:
1. flammability (the ability to burn)
2. Reactivity to oxygen
3. Reactivity with water
4. Reactivity with acids
Chemical Change
• Example: baking a
cake
+
+
=
• A chemical change
occurs when one or
more substances are
changed into
COMPLETELY
DIFFERENT
substances with
DIFFERENT
PROPERTIES
Clues to Chemical Changes
•
•
•
•
•
Change in color
Fizzing
Foaming
Heat
Production of sound, light or odor
Chemical Changes
• Cannot be undone by ordinary physical
means
• Some chemical changes may be undone
by other chemical means
– Example: Water formed in the space shuttle’s
rockets could be split back into hydrogen and
oxygen using electricity