Energy and Change of Matter

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Energy and Change of Matter

• Chapter 15
• General Science
• Mr. Saks

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Objectives

• Explain the difference between potential and
  kinetic energy
• Name five different forms of energy
• Explain how heat energy changes matter
• Describe the difference between physical and
  chemical changes

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Words to Know

• chemical energy Energy stored in molecules.
• condensation The process by which gas turns into
  a liquid.
• electrical energy Energy produced and carried by
  the electrons in a substance.
• energy The ability to do work.
• heat energy Energy produced by the motion of
  molecules.
• kinetic energy Energy in movement. (motion
  energy)

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• light energy Energy produced by the motion of
  waves of light.
• mechanical energy Energy produced by the moving
  parts of a machine.
• nuclear energy Energy stored in the nucleus of
  an atom.
• nuclear fission The splitting of atomic nuclei,
  resulting in great energy release.
• nuclear fusion The joining of atomic nuclei,
  resulting in great energy release.
• potential energy Stored energy (Ex. Cup on a
  table it has the potential to move)

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I. Energy and the Change in Matter

• All the World is Made of Matter
• Takes energy to make matter
• Without Energy ? theres NO movement
• Rivers dont flow
• People cant run
• Planets dont move

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II. What is Energy

• Energy is the ability to do work (move
  something)
• Energy has NO mass
• Energy is in ALL living things
• Potential Energy stored energy
• Examples
• River water behind (above) a dam
• Kinetic Energy Energy in Motion
• Examples
• a. Running river water flowing below the dam

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• Rock on a top of a cliff?
• BUT if it falls?
• Exercise

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• Where do you get energy?
• Food
• Pizza Potential Energy
• Pizza an hour later in your stomach Kinetic
  energy

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III. Types of Energy

• Light Energy
• energy produced by the wave motion of light
• Sun light is energy
• Electrical Energy
• Energy produced by the movement of electrons
• Lightning is an example
• Generators produce electrical energy

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• Chemical Energy is energy stored in molecules
• Molecules are made when atoms join together in
  chemical bonds
• When bonds are broken energy is released
• Cars use chemical energy in gas
• Humans use chemical energy in food

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• Mechanical Energy is the energy released when
  parts of a machine move
• A windmill uses mechanical energy
• A bike does too
• A Car gets its mechanical energy from what?

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• Nuclear Energy is energy stored in atoms
• This is energy released when a large nucleus
  breaks apart
• Nuclear Fission is the breaking apart of a
  nucleus
• Nuclear Fusion is the joining together of nuclei

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• Conservation of Energy
• This says that energy can never be created or
  destroyed
• Energy just changes form
• Solar panels collects light energy and turns it
  into heat energy
• Batteries turn chemical energy into electrical
  energy

• Science Practice
• What form of energy does a bike use?
• What form of energy do plants use in
  photosynthesis?
• What form of energy warms your body from a
  furnace?
• What form of energy does a TV use?

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IV. How Heat Energy Changes Matter

• All changes in matter require some kind of energy
• Heat causes molecules to move faster and further
  apart
• When enough heat is added a solid can change to a
  liquid
• MELTING
• Ice melts to water
• As you add more heat to water
• Molecules move even faster and further apart
  until the water turns into gas
• Evaporation
• liquid to a gas

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• Heat taken away from matter can also change its
  form
• Heat is taken away from a gas it turns back into
  a liquid
• Condensation
• Gas to a liquid
• Heat is taken away from a liquid it can turn into
  a solid
• Freezing
• Liquid to a solid

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• Change in matter because of change in temperature
• Dew on grass in morning is caused by the cool air
  and water _____________ onto the grass
• As day warms up because of light and heat energy
  from the Sun the water on the grass disappears by
  _______________

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V. Physical and Chemical Change in Matter

• Two kinds of change in matter Physical and
  Chemical
• Physical Change
• Affects only the state, shape, or size of the
  matter
• Drop a plate and break it
• Crushing, grinding, tearing are all physical
  changes
• Freezing, melting, boiling, and condensation are
  all physical

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• 2. Chemical Change
• A change that causes a substance with new
  properties to be formed
• Compounds are always a result of chemical change
• NaCl, H2O
• Acid forms when milk sours
• Burning wood chemically changes it from wood to
  Carbon and some gases

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VI. People in Science

• 1938 in the DuPont Company
• Roy Plunkett was told to make a refrigerant
• He mixed chemicals together and let them sit
• He later found they mixed and combined together
  to make a very slippery, white powder
• He created the first plastic, today known as
  teflon
• Today it is used in a lot of non stick pans for
  cooking

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Science Alert

• Sometimes scientists claim they can do things
  they cannot
• Several hundred years ago a group of scientists
  insisted they could make gold
• These people were called alchemists
• James Price actually demonstrated this by mixing
  a red powder with mercury and indeed produced
  real gold
• Royal Society of England invited Price to
  demonstrate his discovery, and he kept making
  excuses as to why he could not
• When he finally was forced to show his work, he
  did and instead of making gold he swallowed a
  poison and died
• Price was a fraud, he faked his experiment