Grade 7 ScienceGrade 7 ScienceUnit 2: HeatUnit 2: Heat

Ch5: The PTM & The States of Ch5: The PTM & The States of MatterMatter

Observing MatterObserving Matter

MatterMatter is anything that has a mass is anything that has a mass and takes up space.and takes up space.

Imagine you could hold a rain drop in Imagine you could hold a rain drop in your hand, how you would describe your hand, how you would describe it? it?

Shape

Volume

Particle Arrangement

Particle Movement

The Particle Theory of The Particle Theory of MatterMatter

1.1. All matter is made up of tiny All matter is made up of tiny particlesparticles..2.2. These particles are always These particles are always movingmoving; they ; they

have have energyenergy..3.3. There are There are spacesspaces among the particles. among the particles.4.4. There are There are attractive forces attractive forces between between

the particles-these attractions may be the particles-these attractions may be strong or weak.strong or weak.

5.5. The particles of one substance differ The particles of one substance differ from the particles of other substances.from the particles of other substances.

States of MatterStates of Matter

As you are already aware, there are As you are already aware, there are three states of matter:three states of matter:– SolidSolid– LiquidLiquid– GasGas

These states can also be explained These states can also be explained using the using the particle theory of matterparticle theory of matter..

States of Matter - SolidStates of Matter - Solid

Let’s consider a pencil. Discuss the following with your class.– Describe the shape of a pencil.– Would this shape change if you were to

put it in your pocket? – How much space (volume) does the

pencil take up?– Would this amount change in your back

pocket?

States of Matter - SolidStates of Matter - Solid A A solidsolid is said to have a is said to have a::

– Definite shape Definite shape since the particles since the particles have:have: very little kinetic energyvery little kinetic energy particles only vibrate particles only vibrate particles are not free to move aroundparticles are not free to move around

– Definite volumeDefinite volume particles are held together by strong forces.particles are held together by strong forces.

States of Matter – Liquid

Now let’s consider a bottle of Gatorade. Discuss the following with your class:– Describe the shape of the Gatorade.– Would this shape change if you were to

put it in a glass?– What is the volume of the Gatorade?– Would this volume change if you poured

it in a glass (if you didn’t spill any!).

Three States of MatterThree States of Matter A A liquidliquid is said to have a: is said to have a:

– Indefinite shape Indefinite shape (shape can change)(shape can change) Particles move more freely (more kinetic Particles move more freely (more kinetic

energy)energy) Particles take the shape of their containerParticles take the shape of their container

– Definite volumeDefinite volume Particles are held together by strong Particles are held together by strong

attractions. attractions.

States of Matter - Gas

Finally, let’s consider air – a gas.– Describe the shape of the air in your

classroom.– Describe the volume of the air.– Now, imagine you can take the air in

your classroom and put it in a larger room. Would the shape change? Would the volume change?

States of Matter - States of Matter - GasGas A A gasgas is said to have a(n):is said to have a(n):

– Indefinite ShapeIndefinite Shape Particles are moving constantly (a lot of Particles are moving constantly (a lot of

kinetic energy) and randomly in all kinetic energy) and randomly in all directions.directions.

Takes the shape of the container and will fill Takes the shape of the container and will fill the container.the container.

– Indefinite VolumeIndefinite Volume Attractions are very weak and particles are Attractions are very weak and particles are

far apart.far apart.

States of Matter ActivityStates of Matter Activity We are going to imagine that we are all We are going to imagine that we are all

particles! What would you be doing in particles! What would you be doing in your classroom if you were a…your classroom if you were a…– Solid particleSolid particle? Act it out!? Act it out!

– Liquid particleLiquid particle??

– GasGas particle? particle?