Unit 3
Changes
 Physical
 Chemical (chemical reactions)
 Nuclear (nuclear reactions)
 Energy
Chapters 2 (2.2 & 2.7), 5 (all), 9 (9.1-9.3)
1
3 States of Matter (Ch. 2.2)
Solids
• a definite shape.
• a definite volume.
• particles are close
•
together in a fixed, rigid
pattern.
particles vibrate very
slowly in fixed positions.
Amethyst (SiO2)
2
Liquids
• not a definite shape, but a
•
•
•
definite volume.
take the same shape as
their container.
particles are close
together, but mobile.
particles move slowly in
random directions.
3
Gases
• not a definite shape.
• not a definite volume.
• the same shape and
•
•
volume as their container.
particles are far apart.
particles move very fast.
4
Summary
5
Physical Properties
6
Three States of Matter for Water
7
Physical Changes
Composition of chemical stays the same!
No new substance is made!
8
Chemical Changes
Original substance/compound/
chemical is changed into new,
different one.
New properties, new composition.
Examples: iron rusting, methane gas burning, sugar caramelizing
9
Summary of Changes of State
(physical change)
10
11
12
13
Heating Curve
• illustrates the changes
•
•
of state as a solid is
heated.
uses sloped lines to
show an increase in
temperature.
uses plateaus (flat
lines) to indicate a
change of state.
14
Heat/energy needed
• Heat of fusion: needed to melt a solid
• Heat of vaporization: needed to vaporize
liquid to gas
Endothermic processes, take up energy
15
Cooling Curve
• illustrates the changes
•
•
of state as a gas is
cooled.
uses sloped lines to
indicate a decrease in
temperature.
uses plateaus (flat
lines) to indicate a
change of state.
16
Heat released
• Heat released when liquid freezes
• Heat released when gas condenses
Exothermic processes
17