Mattar & Force

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Year 7 Science Term 3
Physics
Chemistry
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Year 7 Science Term 3

• Learning Intentions
• How to make further progress
• Class expectations
• To explain the properties of (solids, liquids and
  gases)
• What is a force?

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Year 7 Science Semester 2
How can I improve my learning/study/test skills ?
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TIPS FOR SUCCESS

• Focus 100 EVERY lesson
• Speak up as soon as you dont understand an idea
• Seek help when you need it
• Keep up to date with all set work/homework
• Review lesson PowerPoints regularly
• Write clear and accurate answers
• Answer all set questions as if they are on a test
• Answer/ask questions during presentations

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You Earn Success

• I can accept failure, but I can't accept not
• trying.
• Michael Jordan

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Extra Help

• Email or D11

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Netbooks
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Netbooks

• are only to be opened when requested by a teacher
  or if you have asked been given permission
• lids are to be half down left alone when
  requested
• are to be used appropriately
• create a folder for Term 3

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We do not use class time to

• Check emails unless directed to do so in order to
  open work sent to you.

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Serious Breeches will

• Be reported resulting in a ban on using your net
  book parents being contacted.

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Your netbook is for your education when it is
used at school.
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Class Expectations
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Everyone has the right to learn and achieve their
best.
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Improvements Needed

• Ability to fully focus as work is explained
• Completing all set work on time
• Writing quality answers (detail)
• Asking for help when needed
• What can you do to improve?

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ChemistryStates of Matter
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Making A Substance

• Copper doesnt react with normal acid, but
• it reacts with concentrated nitric acid.

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Copper and concentrated nitric acid
http//www.youtube.com/watch?vKlOEskpy2-0feature
related
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The Reaction
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Nitrogen Dioxide Gas
The gas made is nitrogen dioxide . It is
dangerous and toxic in high concentrations and
forms whenever there is nitrogen and high
temperatures e.g. car engines.
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THREE MAIN STATES OF

MATTER

• SOLIDS LIQUIDS GASES

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Give an example of part of the human body that is

• Solid
• Liquid
• Gas

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Solids, Liquids Gases

• Solids Liquids Gases

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Solids, Liquids Gases

• Have three common properties.

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If I tear up a piece of paper and keep tearing it
up even when the bits are microscopic and I have
to use a laser, will I eventually end up with
nothing?
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The smallest piece of matter

• is an atom.

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What do solids, liquids gases have in common?

• All matter is made up of tiny invisible
• particles (atoms)

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In some substances

• atoms can exist in groups called

molecules
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Water particles

• Chemists write water as
• Water is made up of molecules and each
• molecule contains two hydrogen atoms
• and one oxygen atom.

H2O
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Solids, liquids gases are all made up of atoms
or molecules.

• Table sugar is made up of sucrose molecules,
  C12H22O11

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Solids, liquids gases are all made up of atoms
or molecules.

• Ethanol is made of molecules, C2H5OH

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Solids, liquids gases are all made up of atoms
or molecules.
Nitrogen dioxide gas is made up of NO2 molecules.
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Atoms and molecules are very small.

• How many water molecules
• are in a single drop of water?
• Approximately 3.0 x 1021
• 3.0 x 1021 3,000,000,000,000,000,000,000

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ATOMS ARE VERY SMALL

• 10,000,000 Mg atoms fit across a tiny pinhead.

4,000,000,000,000,000,000,000,000 Al atoms are
found in a typical soft drink can.
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ATOM SIZE

• If atoms were the size of jelly beans
• 4,000,000,000,000,000,000,000,000 atoms (the
  number makes up a soft drink can)
• would cover Australia to a depth of 70 km

70 km equals the distance from Melbourne to
Geelong
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Solids, liquids and gases

• are made up of atoms and molecules (particles).
• atoms are very small.

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Solids liquids take up space.

• What about gases?

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Demonstrations
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Demonstrations
The balloon in the conical flask cannot be blown
up because the air in the flask between the
balloon and glass takes up space.
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Demonstrations
The plastic bag cannot be pushed into the jar
because of the air inside the jar and bag already
taking up space.
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Demonstrations
Air trapped in the cup keeps the tissue dry. A
ping pong ball can be pushed under water using a
cup as the air in the cup takes up space.
http//www.fizzicseducation.com.au/experiments/vid
eos/air20takes20up20space.html
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Solids, Liquids Gases

• All take up space

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Solids and liquids have mass
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Do gases have mass?
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Experiment
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Experiment

• Weigh empty balloon
• Blow up balloon and reweigh
• Empty balloon 1.24 g
• Full balloon 1.29 g
• So gases do have mass

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The larger balloon with more air has a greater
mass
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Gases do have mass

• http//www.youtube.com/watch?vNifhnt6lnUg

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Explain

• An empty balloon reaches ground first when
  dropped with a full balloon

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Air Resistance

• The larger balloon has to push more air out of
  the way as it falls to the ground.
• Air takes up space.

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Matter

• Takes up space
• Has mass
• Is made up of tiny invisible particles

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Which state(s) has a definite shape?

• Solids have a definite shape.
• Liquids and gases take the shape of their
• container.

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Which states of matter have a definite size /
volume?

• Solids and liquids have a definite size or
  volume.
• Gases have the volume of their container.

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Which states of matter flow?

• Liquids and gases are fluids because they flow.

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Is sand a solid or a liquid?

• Each piece of sand is a solid with a fixed volume
  and shape.

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What will happen when the glass plate between the
two jars is removed?
The bromine gas will spread so it fills up both
gas jars
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Diffusion of a Gas
https//www.youtube.com/watch?vH7QsDs8ZRMI
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Diffusion
is the movement of a substance from a region of
high concentration to a region of low
concentration.
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Do solids or liquids show diffusion?

• If liquids dissolve in each other they will show
  diffusion.

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Do solids undergo diffusion?

• Solids do not show diffusion.

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Compress a liquid and a gas
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Compressibility

• If we can compress something we can push it into
  a smaller volume.

https//www.youtube.com/watch?vWrM5SQrRTMM
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Compressibility

• Only gases are easy to compress

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Properties of Solids, Liquids Gases

• Use a grey lead pencil to put a tick, cross or
  question mark in each column.
• Stick the table in your book

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Property Soilds Liquids Gases
Has a definite size/volume
Can be easily compressed
Takes the shape of its container
Can diffuse
Can flow
Always fills its container
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Property Soilds Liquids Gases
Has a definite volume
Can be easily compressed
Takes the shape of its container
Can diffuse
Can flow
Always fills its container
YES
YES
NO
YES
NO
NO
YES
YES
NO
YES
YES
NO
NO
YES
YES
NO
NO
YES
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A closer look at matter

• is needed to explain the properties of solids,
  liquids gases e.g. why do solids have a fixed
  shape volume, unlike gases?

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We need to look at how the particles are arranged.
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PARTICLES IN A SOLID

• are packed tightly together
• are strongly attracted to each other by
• electrostatic forces
• vibrate up down side to side
• but overall remain in one position
• do not have much kinetic energy

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Another Model of A Solid
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Particles In A Liquid

• Are usually packed more loosely
• Attractive forces between particles are not as
  strong as in a solid
• Can slide past each other and swap places
• Have more kinetic energy than particles in a solid

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PARTICLES IN A GAS

• have more kinetic energy
• are no longer attracted to each other
• Large empty spaces exist between particles
• move faster than in a solid or liquid

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States of Matter

• https//www.youtube.com/watch?vGxwj24mREyA
• http//phet.colarado.edu/en/simulation
• Interactive activity.

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Only gases can be easily compressed. Explain.
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Why can only gases be compressed?

• There are large empty spaces
• between gas particles and
• if we put a force on the gas
• we can push the particles
• closer together.

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Gases cause a pressure on the walls of their
container

• When gas particles hit the walls of their
  container they cause a pressure on the walls.
• The harder and faster the particles hit the
  larger the gas pressure.

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When we compress a gas what happens to the gas
pressure inside the container?

• The gas pressure increases as the gas particles
  hit the inside walls more often.

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Why do solids and liquids have a definite volume,
but a gas has the volume of its container?

• Attractive forces keep the
• particles in solids and liquids
• close together, but there
• are no attractive forces
• between gas particles
• so they keep spreading
• until they fill their container.

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Why do gases spread so quickly?
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Gases spread quickly ..

• Particles in a gas
• have lots of kinetic
• energy and move
• quickly.
• Large empty spaces
• between gas particles also
• allow gases to spread quickly.
• Gases spread by diffusion.

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What is diffusion?

• Diffusion is the movement of a substance from an
  area of high concentration to an area of low
  concentration.

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When a solid dissolves in a liquid it diffuses
slowly. Explain.

• Because liquid particles
• are tightly bunched
• together and the particles
• have less energy.

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Dissolving and Diffusion

• Add a few crystals of potassium permanganate to
  cold water and hot water.
• What do you predict?

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The potassium permanganate dissolves and diffuses
fastest in hot water
Icy cold water
Hot water
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What happens when a substance dissolves?
http//www.mhhe.com/physsci/chemistry/essentialche
mistry/flash/molvie1.swf
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Salt dissolves in water

• The sodium and chloride particles that make up
  salt are attracted to water molecules become
  surrounded by water molecules.

http//www.mhhe.com/physsci/chemistry/essentialche
mistry/flash/molvie1.swf
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When potassium permanganate is added to water.

• The potassium permanganate dissolves and
• diffuses through the water.

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Why?

• Potassium permanganate dissolves and
• diffuses faster through hot water.

http//www.middleschoolchemistry.com/multimedia/ch
apter1/lesson2heating_and_cooling
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Dissolving Diffusing Faster

• In hot water the water molecules have more energy
  hit the surface of the solid crystals more
  often and forcefully helping the solid to
  dissolve.
• Fast moving water molecules also help the
  potassium permanganate particles move faster
  through the water.

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Which glass has the hot water?
Hot Cold
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Matter

• Takes up space
• Has mass
• Is made up of tiny invisible particles
• Exists in three main states solids, liquids and
  gases

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Particles are arranged differently in solids,
liquids and gases and move at different speeds.
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Matter Demonstrations

• Explain your observations for the following
  experiments.

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Experiment 1

• Place a small amount of water in a small conical
  flask and attach a balloon.
• Heat the flask until the water boils.

https//www.youtube.com/watch?v5M_XtIVE_u4
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Experiment 2
Add about 20 ml of water to an empty aluminium
can. Heat the can until the water boils for
several minutes. Invert the can and plunge it
into cold icy water
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Experiment 1

• When the flask with the attached balloon was
  heated the balloon expanded.
• The water turned to steam and the air in the
  balloon was heated.
• More gas particles more energetic particles
  were hitting the inside walls of the balloon so
  the air pressure in the balloon increased.

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What else can we do to a balloon to increase the
air pressure inside a balloonbesides heating it?
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What can we do to a balloon to increase the air
pressure inside the balloon?

• Blowing more air into the balloon means more
  collisions between gas particles the internal
  walls of the balloon.
• 2.Squeezing the balloon reduces
• its volume gas particles have
• less distance to travel before
• hitting the internal walls causing
• more frequent collisions.

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Is there any gas pressure outside the balloon?
There is gas pressure outside the balloon because
there are gas particles hitting the outside of
the balloon.
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Experiment 2
The can imploded. What caused the can to implode
?
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What happened when the can was heated?

• The water molecules gained energy
• Liquid water changed to a gas (steam)
• Some steam escaped from the can and this forced
  any air out of the can.

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On heating
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What happened when the can was cooled?

• Steam particles in the can
• lost energy
• moved slower
• The steam condensed back into liquid water so
  there are fewer gas particles in the can.
• What caused the can to implode?

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• When cooled suddenly
• Fewer gas particles hit the inside walls of the
  can
• Any gas particles in the can hit the inside walls
  with less force and less frequently
• The air pressure inside the can drops lower than
  the pressure outside the can

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Imploding Can

• http//hyperphysics.phy-astr.gsu.edu/hbase/kinetic
  /pdrum3.htmlc1
• https//www.youtube.com/watch?vJsoE4F2Pb20
• http//www.chem.iastate.edu/group/Greenbowe/sectio
  ns/projectfolder/animations/CrushthecanV8.html

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Experiment 3
Watch what happens when a balloon is placed in
liquid nitrogen, (b.p. -196oC).
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What happens if a balloon is placed in liquid
nitrogen?
http//www.youtube.com/watch?vZgTTUuJZAFs
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Experiment 3

• The liquid nitrogen is so cold the gases in the
  balloon condense and the air pressure in the
  balloon drops below the pressure outside the
  balloon.
• The balloon inflates as it warms up again and the
  molecules gain energy increasing the air pressure
  in the balloon again.

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Resources

• http//www.bbc.co.uk/bitesize/ks3/science/chemical
  _material_behaviour/behaviour_of_matter/activity/

• Wait for the tutorial to download.
• Take the short quiz at the end

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Homework

• To complete ecology task from last term.
• When the task is completed you can upload it as a
  learning task (Remember to save before
  submitting)
• You may submit hard copies of the work.
• The task is due Monday 21st July