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Solids, Liquids,

and Gases

Presented by Kesler Science

Vers. 08/2020 © Kesler Science, LLC

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Essential Questions:

Reflect on the Essential Questions before you dive in…

1. If you were quizzed today, which parts of the question would you know the answers to already?

2. Which parts of the question would you need to learn more about to answer confidently?

What changes occur in particle motion, temperature, and state of a pure substance when thermal energy is added or removed?

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States of Matter

Also known as phases
Describes a physical property

They are:

Solid
Liquid
Gas

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Kinetic Theory of Matter

All matter is made of tiny particles (atoms or molecules), which are in constant motion

How tightly these particles are packed or bonded determines what state they take

What do you notice about the particles in the three states of matter shown here?

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Kinetic Theory (cont.)

Particles vibrate or move around more if the matter is heated

Particles vibrate or move around less if the matter is cooled

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“M & Ms melt in your mouth not in your hands.”

This was a very famous advertisement slogan.

What scientific principle was the candy company referring to?
Try to explain why M&Ms melt in your mouth and not in your hand.

Words to use as you discuss this problem:

energy, heating, cooling, phase change, state of matter

Think About It

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Solids

Have a definite shape and a definite volume

Particles are tightly packed, vibrating about a fixed position

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Liquids

Have a definite volume, but no definite shape

They take the shape of their container

Particles are tightly packed, but far enough apart to slide over one another

How does a liquid differ from a solid?

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Gases

Have no definite volume and no definite shape

They take the shape of their container

Particles are very far apart and move freely except when they collide

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Changes of State

Adding or removing thermal energy causes a change in state of matter

States can change from one state to another

What is needed for matter to change states?

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Phase Changes
Description of Phase Change	Terms for Phase Change	Heat Movement During Phase Change
Solid to Liquid	Melting	Heat goes into the solid as it melts
Liquid to Solid	Freezing	Heat leaves the liquid as it freezes

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Phase Changes (cont.)
Description of Phase Change	Term for Phase Change	Heat Movement During Phase Change
Liquid to gas	Vaporization, includes boiling and evaporation	Heat goes into the liquid as it vaporizes
Gas to liquid	Condensation	Heat leaves gas as it condenses
Solid to gas	Sublimation	Heat goes into the solid as it sublimates

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Phase Change Diagram

A type of chart that shows conditions at which phase changes occur

The horizontal lines indicate points where there is no temperature change

Freezing and melting points are actually the same temperature

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Contracting and Expanding During Phase Change

Heating liquids and solids

Particles move faster

This faster motion causes the particles to move apart resulting in expansion

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Contracting and Expanding During Phase Change

Cooling liquids and solids

Particles slow down

Attraction between particles pulls them close together causing them to contract

What does the word contract mean?

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Contracting and Expanding During Phase Change

Heating gases inside a balloon:

Particles move faster
Particles hit inside of balloon more frequently with more force
Results in higher pressure inside balloon than outside

Causes expansion of balloon

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Contracting and Expanding During Phase Change

Cooling gases inside a balloon:

Particles slow down
Particles hit inside of balloon less frequently and with less force
Results in lower pressure inside balloon than outside

Causes contraction of balloon

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Give your best answer to...�

Explain what changes occur in particle motion, temperature, and state of a pure substance when thermal energy is added or removed.

Check for Understanding

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Still have questions?

Which parts of the essential question do you still need help to understand?