1. Nuclear Chemistry
Bravo – 15,000 kilotons

2. GSE Standard
SPS4. Obtain, evaluate, and communicate information to explain the changes in nuclear structure as a result of fission, fusion and radioactive a. Develop a model that illustrates how the nucleus changes as a result of fission and fusion. c. Construct arguments based on evidence about the applications, benefits, and problems of nuclear energy as an alternative energy source.

3. Essential Question
What makes an element
radioactive and what does it “accomplish” when it undergoes radioactive decay?
What are the benefits and risks of nuclear power? Do you think we should build more nuclear power plants?

4. Learning Target You should know what makes an
element radioactive and why some elements decay.
You should know the benefits and risks of nuclear energy.

5. An unstable nucleus releases energy to become more stable.
What is radioactivity?
Radioactive decay is the process in which an unstable atomic nucleus loses energy by emitting radiation in the form of particles or electromagnetic waves. Elements with atomic numbers greater than 83 are all radioactive.
A nucleus is unstable if the ratio of protons and neutrons is unbalanced. There are numerous types of radioactive decay. KEY IDEA:
An unstable nucleus releases energy to become more stable.
Science Park HS -- Honors Chemistry

6. Nuclear Symbols Isotopes
Element
symbol
Mass number
(p+ + no)
Atomic number
(number of p+)
Isotopes

7. Types of Radioactive Decay
alpha production (a, He): helium nucleus
beta production (b, e):
gamma ray production (g):

8. Radioactivity Some nuclei are unstable.
They can change into isotopes or different elements.
Types of nuclear radiation: alpha particles, beta-particles, gamma rays

9. Nuclear Stability
Decay will occur in such a way as to return a nucleus to the band (line) of stability.

10. Alpha Radiation
Alpha decay is limited to VERY large, nuclei such as those in heavy metals.

11. Alpha Particles (a)
Alpha particles are made of a helium nucleus and contain 2 protons and 2 neutrons.
(+)positively charged
Massive, weigh 4 a.m.u.
Stopped by paper or skin
In alpha decay the atomic mass decreases by 4 and the atomic number decreases by 2
The products should add up
to the reactants

12. Beta Radiation
Beta decay converts a neutron into a proton.

13. Beta Particles (ß)
Beta particles are formed from break down of a nucleus into 1 e- and 1 proton.
The beta particle is a fast moving electron.
(-) negatively charged, insiginificant mass.
The e- is thrown from nucleus.
Faster than alpha particles
Stopped by a thin sheet of metal
Because a neutron is changed into a proton, the atomic number goes up by 1, but since they both weigh the same the atomic mass stays the same.

14. Gamma Rays/Radiation Part of the electromagnetic spectrum
It is an emission of energy, NOT a particle like alpha and beta
No charge, no mass
Fastest, most penetrative, most energy of all types of decay
Stopped by lead or thick concrete
Most dangerous
The nucleus is unaffected by gamma radiation so the atomic mass and number stay the same

15. 3 Common Types of Radioactive Emissions - Penetrability
Alpha particles may be completely stopped by a sheet of paper, beta particles by aluminum shielding. Gamma rays, however, can only be reduced by much more substantial obstacles, such as a very thick piece of lead.
Science Park HS -- Honors Chemistry

16. Alpha Particle Emission Beta Particle Emission
Gamma Ray Emission
Symbol or
Mass
Heavy
Light
No Mass
How it changes the nucleus
Decreases the mass number by 4
Decreases the atomic number by 2
Converts a neutron into a proton
Increases atomic number by 1
No change to the nucleus
Penetration
Low
Medium
High
Protection provided by…
Skin
Paper, clothing
Lead
Danger

17. CA Standards
Students know protons and neutrons in the nucleus are held together by nuclear forces that overcome the electromagnetic repulsion between the protons.
Students know the energy release per gram of material is much larger in nuclear fusion or fission reactions than in chemical reactions. The change in mass (calculated by E = mc2) is small but significant in nuclear reactions.

18. Fission
Fission - Splitting a heavy nucleus into two nuclei with smaller mass numbers.

19. A Fission Reactor

20. Deuterium – Tritium Fusion Reaction
Fusion - Combining two light nuclei to form a heavier, more stable nucleus. The sun makes its energy by fusion.

21. Fission vs. Fusion Fission is the breaking down of a nucleus
Fission can start chain reactions
Fusion is combining nuclei
Both release a ton of energy

22. Radiation can be Your Friend (sometimes)
Radiation in our world
Helpful
Harmful
Smoke alarms
Treat cancer
Tracers in medicine
Tracers in geology
Nuclear power-fission
Can be natural-soil, sun, water, plants
Our sun emits solar radiation
Can actually change DNA and cause birth defects