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4-5: Radioactive Elements
What types of particles and energy can radioactive decay produce?
Anticipatory Set
What do you know about radioactivity?
California StandardsScience Standard 8.7.b: Students know
each element has a specific number of protons in the nucleus (the atomic number) and each isotope of the element has a different but specific number of neutrons in the nucleus.
Inputradioactive decay: the atomic nuclei of unstable
isotopes release fast-moving particles and energy.radioactivity: The ability of a substance to
spontaneously emit radiation; a property of unstable isotopes.
alpha particle: A type of nuclear radiation consisting of two protons and two neutrons.
beta particle: A fast-moving electron given off by a nucleus during radioactive decay. Beta decay occurs in atoms that are unstable because they have too many neutrons.
Inputgamma radiation: high-energy waves, similar to X-
rays.tracer: Radioactive isotopes that can be followed
through the steps of a chemical reaction or an industrial process.
Input & ModelingDiscovery of Radioactivity
In 1896, the French scientist Henri Becquerel discovered the effects of radioactive decay by accident while studying a mineral containing uranium.
He observed that with exposure to sunlight, the mineral gave off a penetrating energy that could expose film.
Becquerel thought sunlight was necessary for the energy release.
He found out by accident, when he placed the mineral in a desk drawer next to a photographic plate, that sunlight was not needed.
The mineral had created an image on the photographic plate!
Input & ModelingDiscovery of Radioactivity
Becquerel presented his information to a young researcher, Marie Curie, and her husband, Pierre.
The Curies concluded that a reaction was taking place within the uranium nuclei.
Marie Curie called this property radioactivity.Eventually, the Curies isolated 2 new elements,
which Marie named polonium and radium.
Input & ModelingTypes of Radioactive Decay
Radioactive decay can produce alpha particles, beta particles, and gamma rays.
The particles and energy produced during radioactive decay are forms of nuclear radiation.
Input & ModelingTypes of Radioactive Decay
Alpha and beta decay are almost always accompanied by gamma radiation.
Gamma radiation consists of high-energy waves, similar to X-rays.
Gamma rays can cause severe damage to human cells.
Input & ModelingTypes of Radioactive DecayDuring alpha
decay, a nucleus loses an alpha particle, which consists of two protons and two neutrons.
Input & ModelingTypes of Radioactive Decay
During beta decay, a neutron inside an unstable nucleus changes into a negatively charged beta particle and a proton.
Input & ModelingTypes of Radioactive Decay
Gamma radiation has no charge and does not cause a change in either the atomic mass or the atomic number.
Input & ModelingTypes of Radioactive Decay
The three types of nuclear radiation were named based on how easily each one could be blocked. Alpha, beta, and gamma are the first three letters of the Greek alphabet.
Input & ModelingUsing Radioactive Isotopes
Uses of radioactive isotopes include tracing the steps of chemical reactions and industrial processes, and diagnosing and treating disease.
Doctors use tracers to detect medical problems in body organs and other structures like bones.
Gamma radiation is used to kill cancerous tumors.
Input & ModelingUsing Radioactive Isotopes
Tracers are radioactive isotopes that can be followed through the steps of a chemical reaction or industrial process.
What is the property of a substance to be able to spontaneously emit radiation.
Check forUnderstanding
radioactivity
What is a radioactive isotope that can be followed through a chemical reaction or a process because it gives off radiation?
tracer
Answer #1, 2, 3
Guided Practice
Independent PracticeFinish the worksheet.
EXTENSION Write a detailed SUMMARY of the section and
complete the UNANSWERED QUESTIONS section of your notes.
Choose two of the remaining Depth & Complexity ICONS in your notes and explain how they relate to this section.
