Nuclear Radiation

Nuclear Chemistry? Or Quantum Physics? What we have learned in this course is the nucleus consists of protons and neutrons. This is an oversimplification as there is a lot more going inside the nucleus! For one, how in the world do positively charged particles – which REPEL – exist together in a tightly packed nucleus?!? A very strong force holds the nucleus together, fittingly called the “strong force” The presence of neutrons stabilizes the nucleus; more protons requires more neutrons to make it stable What else is in the nucleus? Turns out – plenty! Quarks, they come in 3 different colors of 6 different flavors: up, down, top, bottom, strange, and charm Leptons, they also come in 6 flavors: electron, muon, tau, and their associated neutrinos Or Quantum Physics? chemistry is more concerned with chemical reactions on the atomic level, you can learn more about these particles in advanced physics

Radioactivity In 1903, Marie Curie along with Pierre (her husband) and Antoine Bequerel, win the Nobel prize in physics for their work on radioactivity. They showed that energy emitted from uranium salts fogged photographic plates They called this energy radiation and the process radioactivity Marie Curie died in 1934 from leukemia, caused by her long term exposure to radiation.

Radioisotopes Chemical reactions involve changes in the number and arrangement of electrons to gain stability Nuclear reactions involve changes in unstable nuclei (radioisotopes) that always emit large amounts of energy Unlike chemical reactions, nuclear reactions are not affected by changes in temperature, pressure, or catalysts Radioisotopes will decay regardless of the compound in which they are found

Why are some isotopes radioactive? Just as electrons are more stable in certain numbers and arrangements Nuclei are more stable in certain sizes and compositions The ratio of neutrons to protons is very important to nuclear stability Very large nuclei are also unstable These nuclei spontaneously decay and emit radiation to achieve nuclear stability

Radioactivity Radiation is emitted during radioactive decay There are three main types of radiation: Alpha radiation Beta Radiation Gamma radiation Some other types: Positron Neutron neutrino

Alpha Particles 4 2 +2 He Alpha particles are helium nuclei emitted from a radioactive source Each consist of two Protons and two neutrons and have a +2 charge

Beta Particles e -1 If neutron:proton is too high, a neutron will decay, emitting a beta particle What is left is all the mass of the neutron, and a positive charge So a neutron  proton and a beta particle is ejected Same properties as an electron No mass, -1 charge

γ Gamma Ray Gamma Rays are high energy photons emitted by radioactive isotopes Similar to x-rays No mass No charge Most powerful form of radiation Gamma Rays are usually emitted along with alpha or beta particles during radioactive decay

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