Sections 2 and 3

1
Carbon Chemistry and Radioactivity

• Chapter 8
• Sections 2 and 3
• Chapter 4 Section 5

2

• Monomers- smaller molecules that join together to
  make polymers

3
Natural Polymers

• found in nature, ex. Cellulose (cell walls),
  starch (plant sugar), glycogen (animal sugar),
  silk, wool, proteins

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SyntheticPolymers

• man made, not natural, ex. plastics, nylon,
  polyester, laminate flooring, teflon, CDs

6

• Sometimes the polymer chains get up to 500,000
  carbons long. Here they are tough enough for
  synthetic ice, replacement joints and
  bullet-proof vests. This is called Ultra High
  Molecular Weight PolyEthylene or UHMWPE.    
  Think about it. You start with ethylene gas
  molecules that can't stop a feather from passing
  through them. But after the double-bond of one
  ethylene molecule breaks, it causes a chain
  reaction that connects thousands to it. In less
  than a second, these long straight chains of
  carbon and hydrogen aligned next to each other
  are strong enough to stop a bullet or play ice
  hockey on. Isn't chemistry wonderful?

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Composite

• Combining two or more polymers, each with
  specific useful properties, into one new
  substance that is better than either polymer was
  individually
• Examples
• Natural- wood
• Synthetic- fiberglass, kevlar

8
Nuclear Reactions

• Radioactive decay- when the nucleus in an
  unstable isotope releases fast moving particles
  and energy
• Types alpha (a), beta (ß), gamma (?)

9
Alpha Radiation a

• nucleus loses 2 protons, 2 neutrons and energy
  (sometimes called a Helium nucleus)
• decreases the atomic mass of the element by 4
• decreases the atomic number by 2 (element changes
  new element)
• protection requires thin material like paper

10
Beta Radiation ß

• nucleus loses 1 neutron and energy, the neutron
  breaks into a proton and an electron, only the
  proton remains in the nucleus
• the atomic mass of the element doesnt change
• increases the atomic number by 1 (element changes
  new element)
• protection requires thin layer of plastic or
  metal like aluminum foil

11
Gamma Radiation ?

• gives off extremely high amounts of energy
• protection requires a meter of concrete or 6
  inches of lead

12
Half-Life

• length of time needed for half the atoms of a
  sample to decay
• example- original sample has 32 grams of
  carbon-14 (half-life is 5,730 years)
• after 1 half-life, only 16 grams of carbon-14
  remain
• after 2 half-lives, only 8 grams of carbon-14
  remain
• after 3 half-lives only 4 grams of carbon-14
  remain
• the time needed for the sample to decay from 32 g
  to 4 g is 5,730 x 3 17,190 years.

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