Chemistry - Nuclear Chemistry Notes

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NUCLEAR CHEMISTRY Chemical reactions form bonds by gaining, losing, or sharing _________________. The atomic number, or number of _____________, always stays the same. For example, aluminum always remains aluminum with its _____ protons. NUCLEAR reactions involve _____________ changes in atoms. Atoms that are radioactive (unstable ratio of protons and neutrons) spontaneously change to produce an atom of a different ______________ (one with a different number of protons), and emitted particle, and released energy. There are three types of nuclear radiation: Nuclear Radiation Can be stopped by Penetrating power What is it Symbol Energy Alpha particle Blocked by paper Beta particle Gamma ray strong NUCLEAR FUSION: is a type of nuclear reaction in which two nuclei with low masses fuse together to form one nucleus with a larger mass and release large amounts of energy. Fusion reactions (like the one to the left) are constantly occurring on the surface of the sun. FYI: All elements larger than helium are formed through the process of nuclear fusion! electron High energy photons 0 0

weak

Low

High

NUCLEAR FISSION: is the process of splitting an atom into two nuclei with smaller masses. This occurs in nuclear power plants to produce massive amounts of energy.

NUCLEAR DECAY Nuclear reactions occur because the nuclei are trying to become more stable. An uneven number of _____________ and ______________ cause an unstable nucleus. Any element larger than atomic number _____ (lead) goes through nuclear decay. There are many smaller isotopes like carbon-14 that go through nuclear decay as well. Carbon -14 is used for dating organic materials like _____________. The half-life of carbon-14 is 5730 yrs. Using this number they can tell how long ago an organism lived. Uranium-238 is another common isotope that radioactively decays. The energy released from the decay of uranium-238 is trapped and used as energy in _________ _________ ________. Uranium-238 has a half-life of 4.46 billion years! Polonium-214 has a half-life of only 163.7 microsec.

Pg 814 Figure 25-11

Isotopic Notatio Name Mass #

Like Uranium-2The Mass # is shown at the bottom of the graph

Nuclear Reactions: Find Uranium-238 in the top right corner. It decays to forms___________- ____ (what element in isotopic notation) and releases a(n) ________ particle. When thorium-234 decays, it forms ___________-_____ and releases a _________ particle. When Pa-234 decays it forms __________ and releases a __________ particle. Why does the mass number change when U-238 decays to form Th-234? Why does it form Th? Why does the mass number stay the same when Th-234 decays into Pa- 234? Why does Th form Pa? These nuclear reactions can be represented as follows: U Th In nuclear reactions, just like chemical reaction, mass is CONSERVED. However, unlike chemical reactions, new elements are formed. Pa + e a beta particle was released Th + He an alpha particle was released

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