Changes in Matter

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Chapter 2 Nature of Matter
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Chapter 2 Nature of Matter

• Section 2 Changes in Matter
• Section Keys
• What is a physical change?
• What is a chemical change?
• Standards
• 5.b Students know the idea of atoms explains
  the conservation of matter In chemical reactions
  the number atoms stays the same no matter how
  they are arranged, so their total mass stays the
  same.

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Physical Change

• Any change that alters the form or appearance of
  matter but does not change into a different
  substance
• Remains the same after the change
• Ex tearing paper, bending a nail, changes of
  state (solid to liquid to gas)

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Chemical Change

• When a substance is changed into one or more new
  substances
• Produces new substances with new properties
  different from the original
• Also known as a chemical reaction
• Ex Sulfuric acid and sugar

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Law of Conservation of Matter

• Matter is not created or destroyed
• Mass is not gained or lost
• Also called the law of conservation of mass

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Chapter 2 Nature of Matter
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Chapter 2 Nature of Matter

• Section 3 Energy and Matter
• Section Keys
• What are some forms of energy that are related to
  changes in matter?
• How is chemical energy related to chemical
  change?
• Standards
• 5.c Students know chemical reactions usually
  liberate heat or absorb heat.

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Forms of Energy

• Energy the ability to do work or cause change
• Energy is never created or destroyed in chemical
  reactions it changes from one form to another

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Thermal Energy

• Temperature a measure of the average energy of
  random motion of particles (atoms) of matter
• Thermal Energy total energy of all of the
  particles in an object
• Exothermic Reaction a reaction that releases
  energy in the form of heat
• Endothermic Reaction a reaction that absorbs
  energy

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Chemical Energy

• Chemical Energy stored in the chemical bonds
  between atoms
• When chemical bonds form or break energy is
  given off or taken in

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Electromagnetic Energy

• Electromagnetic Energy (radiation) form of
  energy that travels through space as waves
• Examples ultra-violet, radio, microwave, x-rays

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Electrical Energy

• Electrical Energy energy of electrically
  charged particles moving from one place to
  another
• Electrons move from one atom to another