Warm – Up:
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Warm – Up: Warm – Up: Think about the terms “radiation” and “radioactivity.” On a piece of paper, please write down at least 3 things you think of when you hear these terms. (Hint : what you write down does not have to be a definition: it can be things that use radiation, what these terms make you think of, etc.)
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Warm – Up:. Think about the terms “ radiation ” and “ radioactivity .” On a piece of paper, please write down at least 3 things you think of when you hear these terms. - PowerPoint PPT Presentation
Transcript of Warm – Up:
Warm – Up:Warm – Up:Think about the terms “radiation” and “radioactivity.” On a piece of paper,
please write down at least 3 things you think of when you hear these terms.
(Hint: what you write down does not have to be a definition: it can be things that use radiation, what
these terms make you think of, etc.)
After today you will be able to… Describe the 3 different types of radiation
α - alpha β - beta - gamma
Explain the significance of an isotope’s radioactive half life
4.4 Unstable Nuclei and Radioactive Decay
Vocabulary
Radioactivity-the spontaneous emission of radiation from a substance
Radiation-rays and/or particles emitted from radioactive material
Nuclear reactions- changes in an atom’s nucleus
4.4 Unstable Nuclei and Radioactive Decay
Types of Radiation
Alpha radiation - stream of high energy alpha particles
alpha particles consist of 2 protons and 2 neutrons and are identical to helium-4 nucleus.
symbol: 4He 2+
2
not much penetrating power, travel a few centimeters, stopped by paper, no health hazard
4.4 Unstable Nuclei and Radioactive Decay
mass number decreases by 4 atomic number by 2
alpha decay: 226 Ra 222Ra + 4 He 88 86 2
Example: Uranium-238
4.4 Unstable Nuclei and Radioactive Decay
Beta radiation high speed electrons
To form beta radiation a neutron splits into a proton and an electron
The proton stays in nucleus and the electron propels out at high speed.
Symbol 0e- 0β
-1 -1
100 times more penetrating then alpha radiation, pass through clothing to damage skin
4.4 Unstable Nuclei and Radioactive Decay
Beta decay: 131I 131 Xe + 0β 53 54 -1
Example: Astatine-220
4.4 Unstable Nuclei and Radioactive Decay
Gamma radiation similar to X rays doesn’t consist of particles
symbol: 0 0
penetrates deeply into solid material, body tissue, stopped by Pb or concrete, dangerous
usually emitted with alpha and beta radiation no mass or electrical charge emission of gamma rays by themselves cannot
result in the formation of a new atom
Radioactive or Not: That is the
question!
What determines if something is radioactive or not?
Radioactive or Not: That is the
question!
What determines if something is radioactive or not?
Atoms with an unstable proton to neutron ratio will undergo radioactive decay according to
their half life!
4.3 How atoms differ Isotopes:
Isotope – atoms of the same element with different numbers of neutrons (different mass #)
Examples: Carbon – 12 Carbon – 14 (used in carbon dating)
Hydrogen – 1 (protium) Hydrogen – 2 (deuterium) Hydrogen - 3 (tritium)
Before You Go: Please answer the following questions on a
piece of paper and hand it to me before you leave!!!
1. What is one thing you learned today about radioactivity or one misconception that is now cleared up?
2. What is one question you still have about radioactivity or radiation?
