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Nuclear Chemistry Objective: To explain the process of radioactive decay using nuclear equations and half life. Essential Question: How do unstable (radioactive) isotopes become stable? . Radioactivity introduction -. Radioactivity video – 4 minutes

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slide1

Nuclear ChemistryObjective: To explain the process of radioactive decay using nuclear equations and half life

Essential Question: How do unstable (radioactive) isotopes become stable?

radioactivity introduction
Radioactivity introduction -
  • Radioactivity video – 4 minutes
  • http://ed.ted.com/lessons/radioactivity-expect-the-unexpected-steve-weatherall
  • Review questions:
  • http://ed.ted.com/lessons/radioactivity-expect-the-unexpected-steve-weatherall#review
  • Dig deeper:
  • http://ed.ted.com/lessons/radioactivity-expect-the-unexpected-steve-weatherall#digdeeper
review radioactive isotopes
Review: Radioactive Isotopes

A radioactive isotope has an unstable nucleus that undergoes spontaneous changes.

  • Emits particles
    • 1.
    • 2.
  • Emits energy in the form of __________ waves.
  • Transmutates into another element
nuclear chemistry
Nuclear Chemistry

Student notes

  • Atomic nucleus: compared to the whole atom
    • (also called the nuclide)
  • Mass:
  • Energy
  • Volume
strong nuclear force holds the nucleus together
Strong Nuclear Force:Holds the nucleus together

Limit to the # neutrons: A nucleus with too many neutrons will be unstable and change

nuclear chemistry1
Nuclear Chemistry
  • Most atoms have tremendously stable nucleus
    • Exist for billions of years
  • A radioactive isotope has an unstable nucleus which undergoes spontaneous changes.
    • Note: spontaneous change ⇏ fast change
  • Transmutates into another element
    • The nucleus changes (different number of protons):
  • Emits particles and energy:

Unstable isotopes are changing to become stable

Student notes

types of radiation
Types of Radiation

Understand the following slides on radiation emissions to complete the table in your notes.

particles emitted from a radioactive isotope
Particles emitted from a radioactive isotope

Next slide

Type Symbol Charge Mass Rad.Strength

slide13

Penetrating ability of different particles:Radition strength: how each of the radioactive emissions are blocked.Which is the most damaging (strongest)?

nuclear reactions
Nuclear reactions
  • Represents the nuclear changes
    • Use symbols to represent
  • The isotope before and after the change
  • The particles which are emitted
  • Before and after must balance
balancing nuclear reactions
Balancing Nuclear Reactions
  • Student notes:
  • Totals number of atomic numbers (A ) and total mass numbers (Z) must be the same before and after the reaction.
  • Keep track of atomic number (Z) and mass number (A): protons & neutrons
  • Shown by “Before” “ After”
nuclear reactions1
Nuclear reactions

Student notes

Total number of atomic numbers and the total mass numbers must be equal on both sides of the equation.

Examples:

nuclear equations
Nuclear Equations
  • 23892U  23490Th + ?
  • 146C  0-1e + ?
  • 23994Pu + 42He 

Nuclear Equations Practice Website

nuclear reactions emission of alpha or beta particles
Nuclear Reactions Emission of Alpha or Beta particles
  • http://phet.colorado.edu/en/simulation/beta-decay
  • http://phet.colorado.edu/en/simulation/alpha-decay
radioactive decay
Radioactive decay

Student notes:

Notwo radioactive isotopes decay at the same rate. Therefore, decay rate can be used to identify the isotope. Decay is measured by half life.

half life
Half-life
  • Measure of Radioactive decay rate.
  • Measured as the time it takes for ½ of a sample of radioisotope’s nuclei to decay into its products.
half life1
Half Life

4.5 years

12.5 g

half life2
Half Life:
  • http://phet.colorado.edu/en/simulation/radioactive-dating-game

Number of radioactive isotopes

Number of years

fission and fusion
Fission and Fusion
  • http://phet.colorado.edu/en/simulation/nuclear-fission
half life calculations
Half life Calculations
  • How much of a 100g sample of an unstable isotope remains after 25 years if the half life is 5 years?
  • Determine how many “half life intervals”.
  • Calculate the amount of original sample remaining after each ½ life

100g

  • Simplify the calculations
half life problems
Half Life Problems
  • How much of a 100g sample of an unstable isotope remains after 25 years if the half life is 5 years?

3.1 g

half life problems1
Half Life Problems
  • How much of a 60g sample of an unstable isotope remains after 2 days if the half life is 12 hours?

7.5 g

half life problems2
Half Life Problems
  • How much of a 20 g sample of an unstable isotope remains after 3 sec if the half life is 0.5 seconds?
fission and fusion1
Fission and Fusion
  • http://phet.colorado.edu/en/simulation/nuclear-fission
origins of element

Origins of Element

Reading Analysis:

got calcium
Got Calcium
  • Where are most elements created?
  • When was H and He created?
  • What elements are made by small stars?
  • What additional elements are made by large stars?
  • What elements are made by supernovae (large exploding stars)?