Warm Up 10-5-15

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Warm Up 10-5-15

• Ra-225 half-life is 15 days, how many grams are
  left after 45 days if you started with 90g?
• How can a unstable isotope (radioactive) become
  normal?
• Can radiation be good?

Agenda -Go over quiz-Notes Unit 3-5 -Finish WS
Nuclear decay
HomeworkOct 9 - Test Unit 3Oct 9 - Midterm Exam
(45 Qs)Oct 9 - Online HW Unit 3
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Quiz Unit 3

• Version 2
• v.e. 2, total e 38
• F, S, P, Ga
• Noble gases
• I and F

• Version 1
• v.e. 5, total e 15
• N, Ge, In, Hg
• Alkaline earth metals
• Si and B

5. False, moving across the period also add more
electrons to the atom but radius decreases 6.
Atomic mass and properties
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Unit 3-5Characteristics of Nuclear Decay
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Characteristics of Some Radiation
Alpha- weakest, a thin barrier can stop (they are
big and heavy and cant travel very far)
Beta- clothing, wood, or aluminum can stop this
radiation.
Gamma- highly energized can be stop by concrete
or lead
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Alpha Decay

• Problem the nucleus has too many protons which
  cause excessive repulsion.

• Solution In an attempt to reduce the repulsion,
  a Helium nucleus is emitted.

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Alpha emission (decay)

• 4 2 He

Identify the product formed when uranium-238
alpha decays
4 2 He
234 90 Th
238 92 U
Determines which atom from the periodic table
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Beta Decay

• Problem too many neutrons not enough protons.

• Solution a neutron is turned into a proton and
  one electron is then ejected.

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beta emission (decay)

• 0-1 e

Identify the product formed when carbon-14 emits
beta particle
0 -1 e
14 7 N
14 6 C
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Gamma Decay

• Problem the nucleus is at too high an energy.

• Solution The nucleus falls down to a lower
  energy state and, in the process, emits a high
  energy photon known as a gamma ray.

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gamma emission (decay)

• 00 ?

Identify the product formed when carbon-14
releases gamma rays
0 0 ?
14 6 C
14 6 C
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Explaining mass defect
Emc2 says that mass can be converted into energy
when the nucleus is formed
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Nuclear Fusion

• When multiple nuclei smash into each other
  forming a larger nucleus.

- How our sun produces energy and how hydrogen
bombs work
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• Nuclear Fusion Equations
• Nuclear fusion involves the joining together of
  nuclei.

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Nuclear Fission

• A large nucleus is split into two or more smaller
  nuclei (process sped up by hitting it with a
  neutron)

- Releases Alpha, Beta, Gamma Rays and a lot of
energy
- Used to power nuclear weapons (atomic bombs),
nuclear subs, nuclear power plants
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• Nuclear Fission
• Nuclear fission involves a nucleus breaking up
  into smaller nuclei.

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Nuclear Fission
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Nuclear Fission

• Chernobyl power plant - 1986

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Nuclear Fission

• Fukushima - 2011

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(No Transcript)
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Assignments

• Notes Summary
• Finish the Nuclear Decay worksheet (due today)

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Students Work Ethics Affected by Peers

• 1. What was the main points of this news?
• 2. What was most important in this piece of
  information?
• 3. How can this news be related or impact people
  lives or solve problems/improve society?
• 4. What is your opinion on what you heard?

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Summary of Radiation

• Alpha radiation consists of He nucleus
• 23892 U ? 42 He 23490 Th
• Beta radiation electrons formed by the
  decomposition of a neutron
• 146 C ? 0-1 e 147 N
• Gamma radiation high energy electromagnetic
  radiation often emitted with alpha or beta
  radiation

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Summary of Radiation
Property Alpha radiation Beta radiation Gamma radiation
Composition Alpha particle (He nucleus) Beta particle (electron) High energy EM radiation
Symbol ?, 42 He ?, 0-1 e ?
Penetrating power low moderate Very high
Shielding Paper, clothing Metal foil Lead, concrete