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Anything that has mass and takes up space
Made up of tiny particles called atoms
 Atoms: smallest particle of matter
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Smallest unit of an element that maintains
the properties of that element
Can not be broken down into anything
smaller
Scientists used to think they couldn’t be
split, but we now know that was incorrect
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The physical forms of matter, which include
solid, liquid, and gas
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The state of matter in which the volume and
shape of a substance are fixed
Definite shape
Definite volume
Particles are tightly packed
Particles barely move
 They vibrate in place
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The state of matter that has a definite
volume but not a definite shape
No definite shape
Definite volume
Particles move fast enough to separate a
little
 Allowing them to change shape
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Particles do not move fast enough to
change volume
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Viscosity: a liquid’s resistance to flow
 High Viscosity: Slow Flow (Honey)
 Low Viscosity: Fast Flow (Water)
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Surface Tension: force that attracts the
molecules at the surface of a liquid to form
the drop
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The state of matter that does not have a
definite shape or volume
No definite shape
No definite volume
Particles move so fast that they completely
separate from each other
 Allowing them to change shape and volume
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Change of a substance from one physical
form to another
Requires adding or removing energy so
that particles can speed up or slow down
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Change of state when a solid becomes a
liquid
Particles must speed up
Add energy/heat
Endothermic
Melting Point: Temperature at which a
substance melts
 Water: 32°F or 0°C
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Change of state from a liquid to a solid
Particles must slow down
Remove energy/heat
Exothermic
Freezing Point: Temperature at which a
substance freezes
 Water: 32°F or 0°C
Change of a liquid to a gas (throughout an
entire liquid)
 Particles (on bottom of liquid) must speed up
 Add energy/heat
 Endothermic
 Boiling Point: Temperature at which a
substance boils
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 Water: 212°F or 100°C
 At Sea Level: Boiling depends on Air Pressure
**Won’t happen unless air pressure equals
pressure in bubbles
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Change of a substance from a liquid to a gas
(only on surface)
Particles (on surface) must speed up
Add energy/heat
Endothermic
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Change of state from a gas to a liquid
Particles must slow down
Remove energy/heat
Exothermic
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Change of state from a solid to a gas
 Example: Dry Ice
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Skips liquid stage
Add energy/heat
Endothermic