Fusion is a reaction in which atomic nuclei combine to form a heavier nucleus with the release of energy.
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What are the two things that are produced by nuclear fusion?
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Heavier elements, and energy.
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What kind of elements are created during fusion?
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Elements up to Iron on the periodic table.
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What is the heaviest element that can form through fusion in stars?
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Iron
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What is an atom?
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The smallest unit of any element.
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What is an Element?
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An element is a specific type of atom, determined by the number of protons in its nucleus. The element of an atom determines its properties.
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What particles make up an atom?
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Protons - Positively charged, exist in the atom’s nucleus.
Neutrons - No charge, exist in the atom’s nucleus.
Electrons - Negatively charged, exist outside of the atom’s nucleus.
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What determines what element a particular atom is?
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The number of protons in its nucleus.
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9
What determines the life cycles of stars?
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The star’s mass.
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10
What are the stages for stars with mass similar to the Sun?
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(Protostar) > Main Sequence > Red Giant > Planetary Nebula > White Dwarf
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What are the stages for stars with mass 5-20 times larger than the Sun?
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(Protostar) > Blue Supergiant > Red Giant > Supernova > Neutron Star
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What are the stages for stars with mass larger than 20 times the Sun?
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(Protostar) > Blue Supergiant > Supernova > Black Hole
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How are star mass and star life span related?
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The more mass a star has, the shorter its lifespan will be.
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What is a stellar nebula?
A cloud of gas and dust in space where stars are born.
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What causes the gas and dust in a stellar nebula to collapse?
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Gravity
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What process starts when a star is born?
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Nuclear Fusion
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What is the name for the process of gas in a stellar nebula becoming solid?
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Condensation
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What is the name of the process of smaller objects clumping together to form larger
objects in a stellar nebula?
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Accretion
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What happens to the rotation of the stellar nebula as it collapses?
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The rotation speeds up.
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20
What is radioactive decay?
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The process by which an unstable atom turns into a different atom, accompanied by the release of radiation.
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What is an isotope? Give several examples
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Versions of the same element that have different numbers of neutrons. (e.g. Carbon-14 vs. Carbon-13 vs. Carbon-12. All of these have 6 protons because they are Carbon, but respectively have 8, 7, and 6 neutrons making up the rest of their mass)
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What is a half life?
The amount of time it takes on average for half of a radioactive sample to decay.
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What percent chance does one atom have of decaying during one half life?
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50%
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What percentage of a rock that begins as 100% U-235 will be lead-207 after 1 half life? After 2 half lifes? After 3 half lifes? (Assume all lead-207 is produced through uranium-235 decay)
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50%, 75%, 87.5%
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Why do different isotopes have different length half lifes?
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Their differing masses give them different levels of stability.
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Flashcard (42)