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

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

Review: Radioactivity introduction - Radioactivity video – 4 minutes http://ed.ted.com/lessons/radioactivity-expect-the-unexp

ected-steve-weatherall Review questions: http://ed.ted.com/lessons/radioactivity-expect-the-unexp

ected-steve-weatherall#review Dig deeper: http://ed.ted.com/lessons/radioactivity-expect-the-unexp

ected-steve-weatherall#digdeeper

Review: Radioactive IsotopesA 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

Types of Radiation

Alpha Decay

Beta decay

Gamma Decay

Particles emitted from a radioactive isotope

Type Symbol Charge Mass Rad.Strength

Next slide

Radiation Strength: Explain in your notes how each of the radioactive emissions are blocked.Which is the most damaging (strongest)?

Strong Nuclear Force:Holds the nucleus together

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

Balancing Nuclear Reactions

Keep track of atomic number (Z) and mass number (A): protons & neutrons

Totals of A & Z must be the same before and after the reaction.

Shown by “Before” “ After”

Nuclear reactions

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

Examples:

Nuclear Equations

1. 2713Al + 4

2He ---> 3015P + ?

2. 23892U 234

90Th + ?

3. 146C 0

-1e + ?

4. 23994Pu + 4

2He 24296Cm + ?

Nuclear Equations Practice Website

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

No two 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

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 Life

Decay of a radioisotope

Number of Half-Lives

Elapsed time Amount remaining

0 0 100 g

1 1.5 year 50 g

2 3 years 25 g

3 4.5 years 12.5 g

Examples of the Half Life of Radioactive Elements

Tearing Through a Half Life800 Billion Bismuth-210 Atoms

Time (years)

Half Life:

http://phet.colorado.edu/en/simulation/radioactive-dating-game

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Fission and Fusion

http://phet.colorado.edu/en/simulation/nuclear-fission