Unit 2
1. How do you know matter is made of
particles?
2. What are the particles called?
3. What are the particles doing ?
4. What happens to the particles during a
phase change?
Unit 2
What are some everyday experiences that
show matter is composed of particles—write
down your ideas to share with the class.
What do you think the name of these
particles is?
Unit 2
1. Proof matter is made of particles
ex: blow air into a balloon and it expands
pump up a basketball
wind
air pressure (yardstick demo)
2. Particles of matter called:
ATOMS
Unit 2
Matter is made of small particles called atoms
and can exist in four forms or states:
1. Solid
2. Liquid
3. Gas
4. Plasma
Let’s explore and describe each phase
Unit 2
Solid phase:
1. Particles are as close together as possible.
2. retains a fixed volume and shape
rigid - particles locked into place
3. not easily compressible because of little
free space between particles
4. does not flow easily
5. rigid - particles cannot move/slide past one
another
Unit 2
Arrangement of particles in the solid phase
Unit 2
Liquid phase
1. assumes the shape of the part of the
container which it occupies
2. particles can move/slide past one another
3. not easily compressible because of little
free space between particles
4. flows easily because particles can
move/slide past one another
Unit 2
Arrangement of particles in the liquid phase
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Gas phase
1. Particles are widely separated
2. assumes the shape and volume of its
container
3. particles can move past one another
4. Compressible, reason: lots of free space
between particles
5. flows easily reason: particles can move
past one another
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Arrangement of gas particles
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Plasma phase
1. Similar to gas phase but particles are
charged
2. Electrons have been removed from atom
by addition of energy (heat or electricity)
3. Most abundant phase of matter in the
universe
4. Example would be fluorescent lights
Unit 2
Plasma link
https://www.youtube.com/watch?v=AVEGJZx
glIg
Unit 2
Phase change lab.
Follow instructions in your packet.
Unit 2
Post phase change lab—cooling curve
A
B
C
D
What did you observe in tt at each letter?
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Post phase change lab—cooling curve
A = only liquid
B
C
D
Unit 2
Post phase change lab—cooling curve
A = only liquid
B = first solid
C
D
Unit 2
Post phase change lab—cooling curve
A = only liquid
B = first solid
C = last liq
D
Unit 2
Post phase change lab—cooling curve
A = only liquid
B = first solid
C = last liq
D
= only solid
Unit 2
Post phase change lab—cooling curve
A = only liquid
B = first solid
C = last liq
D
= only solid
What do we say is happening to subst.
between B and C?
Unit 2
a. substance was cooling (losing heat) entire
time.
b. Substance should decrease temperature
entire time.
Problem: if substance was cooling why did
the temperature stop going down?
Unit 2
Material was liquid to begin with, then began
to change to solid—called PHASE CHANGE
----- this phase change is called:
Freezing or Heat of Solidification
-----this happened between letters B---C
----- on what is called the plateau (flat portion)
-----flat = no change in temperature
-----this is then the Freezing Point of the subst.
-----but was cooling entire time!! Losing heat!
Unit 2
Let’s find the pattern! What happened
between pts:
A---B
substance was Cooling
lose heat
temp decreases
all liquid
Unit 2
B---C
cooling
lose heat
freezing or phase change (solid—liq)
Temp constant—Why?? this is science!! Good
labs pose more questions than they answer,
it leads to more labs, it leads us to the truth.
We will find out in a later lab
Unit 2
C---D
cooling
lose heat
temp decreases
all solid
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Phase change lab—heating curve
H
F
G
E
Now you fill in what would be seen at each letter
Unit 2
E = all solid
F = first liquid appears
G = last solid gone
H = all liquid
The material was being warmed (Heated) the
entire time.
Between F—G the substance changed phase
from solid to liquid
Called: Melting (heat of fusion)
Therefore the melting point was = plateau
Unit 2
See anything funny?????
That’s right, melting and freezing pts are the
same temperature!!!
Unit 2
So to melt something heat needs to be added
To freeze something heat needs to be
removed
What is happening to the particles?
When energy added particles move faster
When energy removed particles move slower
Called: Kinetic Molecular Theory
(KMT)
Unit 2
KMT states all matter is made of particles in
constant, endless motion.
Phase
Type of motion
Solid
vibrate
Liquid
vibrate, rotate, translate
Gas
vibrate, rotate, translate
Unit 2
Motion of particles link:
http://www.kentchemistry.com/links/Matter/
phases.htm
Unit 2
Two more terms you must know:
Viscosity and Thermal expansion
Viscosity: ability to flow or pour.
solids = no viscosity
liquids = high viscosity
gases = high viscosity
Unit 2
Thermal expansion:
KMT states particles move faster as heat
(temperature) increases.
Therefore the particles will get farther apart.
The volume of the sample will increase
That’s why a balloon will shrink in the freezer
and expand in the oven!
I guess density will change as well????
Unit 2
Thermal expansion:
If a sample is warmed, what will happen to
the density ?
Answer choice-----INCREASE or DECREASE??
Unit 2
Complete synthesis of slime lab
Unit 2
Post synthesis of slime lab
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Lab: Qualitative description of gas laws
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Post lab gas laws
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Complete boyle’s law lab
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Post Boyle’s law lab
Unit 2
Complete worksheet on gas laws
Unit 2
Complete lab on physical and chemical
properties and changes
Unit 2
Physical property:
A characteristic that can be measured or
observed without changing the nature of the
sample.
Ex:
color, mass, density, odor, volume
Unit 2
Physical change = phase change!
Material does not change
Distance between particles changes!
Solid------liquid------gas
Close---- farther---farthest
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Chemical change:
Only observed if two or more substances
mixed together.
Evidence = change in color
change in temperature
formation of gas (bubbles, odor)
formation of precipitate
(solid from liquid)
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