CH 16 SECTION 4

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CH 16 SECTION 4

• ELEMENTS FROM STARDUST

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A. ATOMIC NUCLEI COLLIDE

• Stars are mostly made of hydrogen
• H exists at high temperatures and pressure
• Our suns core is 15 million degrees C
• The H electron is stripped away creating
• a plasma
• 5. Nuclear fusion occurs
• a. atomic nuclei collide and stick together

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A. ATOMIC NUCLEI COLLIDE

• 6. Inside stars, nuclear fusion combines smaller
  nuclei into larger nuclei, thus creating heavier
  elements
• 7. This also gives off the energy we see as light
  and feel as heat
• 8. For this reason you can think of stars as
  element factories

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B. ELEMENTS FROM THE SUN

• Inside the sun H nuclei fuse together to form He
• The reaction requires the isotope of H that has
  neutrons which is rare on Earth
• This forms He
• Further fusions form He into Be, Be into C, C
  into O
• The size of our sun cant produce anything
  heavier then O
• Scientists believe our sun will run out of fuel
  in about 5 billion years

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C. ELEMENTS FROM LARGE STARS

• Larger stars then our sun get even hotter and can
  produce even larger elements up to iron
• Elements larger then Fe are produced during
  events called supernovas
• A supernova is a tremendous explosion that breaks
  apart a massive star, producing temperatures up
  to 1 billion degrees C
• A supernova provides enough energy for the
  nuclear fusion reactions that create the heaviest
  elements

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C. ELEMENTS FROM LARGE STARS

• 5. Most astronomers agree that the matter in the
  sun and planets around it, including Earth,
  originally came from a gigantic supernova that
  occurred billions of years ago.(If this is true,
  it means that everything around you was created
  in a star. So all matter on Earth is a form of
  stardust!)

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C. ELEMENTS FROM LARGE STARS

• THE END OF CH 16. ARE YOU READY?