Nuclear Chemistry

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Nuclear Chemistry
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• In chemical reactions,
• only the ELECTRONS are
• involved
• There is no change to the nucleus!
• In a chemical reaction, a brand new substance is
  formed

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• In nuclear reactions, there IS a change to the
  atoms nucleus
• In a nuclear reaction, an element may turn into a
  different element

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• A nuclear reaction happens when the
• nucleus of an element
• is UNSTABLE!!
• It has more neutrons or protons than needed

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• When the nucleus of an
• atom is unstable, it starts
• to give off energy (to try
• to get more stable)
• The energy given off is
• called radiation

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• Radiation tiny waves and
• particles that travel at the
• speed of light
• examples x-rays
• UV rays
• microwaves
• infrared light
• radio waves

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• When an atom gives off energy, you can say that
  it emits radiation
• Emitting radiation is spontaneous and doesnt
  require energy
• Radiation can be harmful!

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• When an element emits radiation, it is called
  radioactive decay
• Only certain elements go through radioactive
  decay - usually atomic numbers higher than 83

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• How long it takes for ½ to disappear is called
  half-life
• Carbon-14 has a half-life of 5,730 years
• If you have a 24 g sample of carbon-14, how long
  would it take for you to have only 6 g?

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• Radiation can be detected by a Geiger counter
• A Geiger counter clicks when in the presence of
  radiation
• It tells the absorbed dose (gives a number)

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Three MAIN types of Radiation

• alpha
• beta
• gamma

?
?
?
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alpha (?) particles

• ? particles are large
• ? particles move slowly
• ? particles are most damaging

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• ? particles cannot penetrate very far, so they
  are easy to protect against
• they can be blocked by paper or skin

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• An alpha particle is 2 protons and 2 neutrons
• An alpha particle is a helium atom
• An alpha particle is written as
• He

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beta (?) particles

• ? particles are fast moving electrons
• ? particles are represented by

-
e
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• ? particles can penetrate farther than ?
  particles
• ? particles can be blocked by thin metals and
  protective clothing

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gamma (?) rays

• gamma rays are neutral
• gamma rays are represented by

?
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Gamma (?) Rays

• ? rays are very high energy and penetrate very
  far
• they can be partially blocked by thick lead and
  concrete
• ? rays will sometimes accompany ? and ? radiation

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?
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• Not in Notes
• Discovery of Radiation
• Wilhelm Roentgen- X-rays
• Henri Becquerel- phosphorescent uranium salts,
  spontaneous
• Marie and Pierre Curie- named radioactivity,
  discovered polonium and radium