Summarize the discoveries that led to the discovery of radioactivity.
Wihelm Rontgen-x-rays in 1895. Henri Becquerel discovered radioactivity -studying x-rays. Ernest Rutherford/Paul Villard 3 forms of decay-alpha, beta, gamma
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What happens to an atom during radioactive decay?
Spontaneously emits particles, energy, or both from its nucleus in order to become more stable
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Why are some isotopes stable while others are unstable & experience radioactive decay?
Strong forces holds P & N together in nucleus. Stable= proper ratio of N to P. Unstable= will decay nucleus with a lower energy state, which is more stable.
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Which type of radioactive decay does not result in a new element?
Gamma decay causes a change in energy in the nucleus. It doesn't changes its composition.
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What happens to a sample of an isotope during one half-life?
In one half-life approximately half the nuclei will decay into more stable nuclei.
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Why were scientists surprised that they produced barium after crashing a neutron into a uranium atom?
They were trying to form heavier-than-uranium elements, and barium is significantly lighter.
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What is a chain reaction?
Typically neutrons, from one reaction can start additional reactions.
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In what application of fission would supercritical mass be desired? Explain.
Supercritical mass -goal- fission weapon. The mass would allow the reaction to proceed uncontrolled producing a lot of energy in a short period of time.
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What does it mean for fissionable material to have subcritical mass?
Not enough mass/mass is too spread out to maintain a chain reaction. The neutrons that are produced escape before they can start other reactions.
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How does fusion impact our lives on Earth?
Fusion is essential to life on Earth. Fusion-nuclear reaction-energy from sun Energy is emitted into space-provides food energy for living organisms on Earth.
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Name a manmade source of radiation. Provide 2 examples.
nuclear medicine, medical procedures, electronic devices, food irradiation devices.
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How does CT technology differ from x-rays?
CT combines multiple x-ray images into a cross-sectional image of the body.
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What is a physical change?
Alter the appearance of a substance without changing its chemical composition.
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What is a chemical change?
Alter the composition of compounds by breaking and forming chemical bonds to rearrange atoms into new substances.
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What is a nuclear change?
Convert one isotope into another by changing the composition of the nucleus.
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Why is it surprising that protons remain close together in the nucleus? What force is believed to hold these protons close to each other?
Protons= + charge, & like charges repel. The strong force holds the p's & n's together in the nucleus.