Chapter Three- Solids, Liquids, Gases
CUE WORDS or QUESTIONS
What is a solid?
NOTES WRITTEN
Solid – matter that has a definite volume and a definite shape

The molecules in a solid are closely locked in position and
can only vibrate (move back and forth)
1- Crystalline Solids – particles form a regular, repeating pattern
(salt, sugar, snow)
2- Amorphous Solids – particles are not arranged in a regular pattern
(plastic, rubber, glass)
What is a liquid?
Liquid – has a definite volume, but no definite shape
(no shape of its own but fills whatever container it is in)

Compared to molecules in a solid, the molecules in a liquid are
more loosely connected and can collide with and move past
one another
What is a gas?
Changing states of matter

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Fluid – a substance that flows
Surface Tension – result of an inward pull among the molecules
of a liquid that brings molecules on the surface closer together
(acts like a sort of skin)
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Viscosity – the resistance of a liquid to flow (high viscosity = slow flow)
Gas – fluid that has no definite volume and no definite shape

In gases, the molecules are free to move independently, colliding
frequently, and are far apart from each other

Gas molecules spread apart, filling all the space available to them
Substances can change states of matter (they can change from solid to gas
to liquid) by adding energy or taking away energy
 Solid  Liquid  Gas = gains energy
 Gas  Liquid  Solid = loses energy
SUMMARY
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Melting-
NOTES WRITTEN
Melting – change in state from a solid to a liquid

Thermal energy (heat) is gained
 Melting point – the temp at which the substance begins to melt
When a substance melts, the particles in the solid vibrate so fast that
they break apart and become free from their fixed positions
Freezing-
Freezing – change of state from a liquid to a solid
 Thermal energy (heat) is lost
When a substance freezes, the particles in the liquid move so slowly
they begin to take on fixed positions
Vaporizing-
Vaporization – change from a liquid to a gas
 Takes place when the particles in a liquid gain enough energy
to move independently, forming a gas
 Two kinds – Boiling and Evaporation
1- Boiling – when a liquid changes to a gas on the surface and below
the surface
2- Evaporation – vaporization that takes place only on the surface
of a liquid

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Liquid gains thermal energy
Boiling point – temperature at which a liquid boils
Condensing-
Condensation – change in state from a gas to a liquid
During condensation, the particles in a gas lose enough thermal energy
to form a liquid
Sublimating-
Sublimation – occurs when the surface particles of a solid gain
enough energy that they form a gas
SUMMARY
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