1. Review and Radioactivity
Put together by THE Coach Hyde

2. Radioactivity
Nucleus contains almost all the mass of an atom (p/n have all mass)…electrons are negligible (little mass)
EX. Marble sitting in middle of football field
When a nucleus decays (loses particles) matter and energy is given off (lots of energy)
This happens spontaneously (naturally)
Occurs mostly in large elements because attraction forces aren’t as strong to hold particles within nucleus
Large nuclei are unstable and decay more than small nuclei

3. Nuclear Decay
When unstable nuclei decay…particles and energy (called nuclear radiation) are emitted (given off)
3 types of nuclear radiation
A. Alpha-particles
B. beta-particles
C. gamma-electromagnetic wave

4. Alpha Very massive particle (made of p/n) Most electric charge
Lose energy quickly
Least penetrating power-stopped by paper
Charge =+2…….mass + 4
Transmutation occurs=changing one element to another through nuclear decay

5. symbol

6. Alpha Particle in Depth
1) The nucleus of an atom splits into two parts. 2) One of these parts (the alpha particle) goes zooming off into space. 3) The nucleus left behind has its atomic number reduced by 2 and its mass number reduced by 4 (that is, by 2 protons and 2 neutrons).

8. OK, write the alpha decay equations for these five nuclides
OK, write the alpha decay equations for these five nuclides. The answers are on the next slide

10. Beta particle An electron is emitted (given off) from nucleus decay
Much faster and penetrate more than alpha
Go thru paper….stopped by foil
Undergoes transmutation like alpha
Charge is -1………mass (small)

11.
I e- = Xe

12. 3) The atomic number goes UP by one and mass number remains unchanged.
Beta Decay
Beta decay is somewhat more complex than alpha decay is. These points present a simplified view of what beta decay actually is:
A neutron inside the nucleus of an atom breaks down, changing into a proton.
2) It emits an electron and an anti-neutrino (the anti-particle of a neutron)
3) The atomic number goes UP by one and mass number remains unchanged.
Here is an example of a beta decay equation:

13. Beta Decay Continued
The nuclide that decays is the one on the left-hand side of the equation. 2) The order of the nuclides on the right-hand side can be in any order. 3) The way it is written below is the usual way. 4) The mass number and atomic number of the antineutrino are zero and the bar above the symbol indicates it is an anti-particle. 5) The neutrino symbol is the Greek letter "nu.“
6) Notice that all the atomic numbers on both sides ADD UP TO THE SAME VALUE and the same for the mass numbers.

14. Here's your first set of exercises
Here's your first set of exercises. Write out the full beta decay equation. Then click the link to see the answer

16. Gamma Rays Most powerful and penetrating of all No mass and no charge
Given off by nucleus during alpha/beta decay
Lead and concrete can only stop gamma rays

18. Gamma-rays A nucleus which is in an excited state may emit one or more photons (packets of electromagnetic radiation) of discrete energies. The emission of gamma rays does not alter the number of protons or neutrons in the nucleus but instead has the effect of moving the nucleus from a higher to a lower energy state (unstable to stable). Gamma ray emission frequently follows beta decay, alpha decay, and other nuclear decay processes.

20. Half-life
The amount of time a radioactive isotope takes for half the nuclei of a sample to decay
Very hard stuff so pay attention
Used in science to date rocks, fossils, bones..etc

21. Half Life Table

22. Problems examples
The half life of calcium is 10 days. How much of a 100 g sample will remain after
A. 20 days
B. 30 days
C. 40 Days
D. 50 days

23. Another look
A sample of Phosphorous-18 originally has 30g. Phosphorous-18 has a half life of 2,000 years. In _______________ years, how many grams would remain undecayed?
A. 2,000 yrs
B. 4,000 yrs
C. 8,000 yrs

24. Another look
At the end of 45 days, 100 g of Carbon-14 has decayed to 12.5 g. What is the ½ life of Carbon 14?

25. The Geiger–Müller counter, also called a Geiger counter, is an instrument used for measuring ionizing radiation used widely in such applications as radiation dosimetry, radiological protection, experimental physics and the nuclear industry