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Types of Radiation and Unstable Nuclei

Types of Radiation and Unstable Nuclei. I. Chemical and Nuclear Reactions. Chemical reactions only involve an atom’s electrons Nuclear reactions involve changing an atom’s nucleus Nuclear reactions release a million times more energy than chemical reactions

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Types of Radiation and Unstable Nuclei

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  1. Types of Radiation and Unstable Nuclei

  2. I. Chemical and Nuclear Reactions • Chemical reactions only involve an atom’s electrons • Nuclear reactions involve changing an atom’s nucleus • Nuclear reactions release a million times more energy than chemical reactions • Unlike chemical reaction, nuclear reactions are not affected by temperature, pressure, or a catalyst.

  3. II. Nuclear Vocabulary • Radioactivity – the process of emitting radiation. • Radiation - rays and particles emitted by a radioactive source. • Radioisotopes – isotopes of atoms with unstable nuclei and emit radiation to obtain a more stable nuclei • Radioactive decay - Unstable nuclei losing energy by emitting radiation in a spontaneous process. • Nucleon – refers to both protons and neutrons

  4. III. Which Isotopes are Radioactive? • Small Nuclei - Atoms which contain up to 20 protons (up to Calcium) are usually stable. • Large Nuclei - Larger nuclei tend to be radioactive. All nuclei with 84 or more protons (Polonium and up) are radioactive. For example, all isotopes of Uranium are radioactive. • Atoms with more neutrons than protons - There are radioactive nuclei that have less than 84 protons. These nuclei have more neutrons than protons. For example, Carbon-12 (6 protons and 6 neutrons) is stable, while Carbon-14 (6 protons and 8neutrons) is radioactive.

  5. IV. Why Does an Atom Undergo Radioactive Decay? • Radioactive atoms emit radiation because their nuclei are unstable. • The stability of the nucleus depends on the neutron to proton ratio • Neutrons vs. protons graph stable nuclei found in a region called the band of stability.

  6. V. Types of Radiation – Alpha Radiation • Alpha radiation are attracted to the negatively charged plate • Alpha particles contain two protons and two neutrons (A helium nucleus) • Blocked by paper • Least penetrating form of radiation (only travels a few centimeter in the air) • Carry +2 charge • Symbolized by He or  4 2 4 2

  7. VI. Types of Radiation – Beta Radiation • Beta radiation attracted to the positively charged plate • Carry –1 charge • Beta particles are fast moving electrons • Blocked by metal foil or wood • Medium penetration power (travels a few meters in the air) • Symbolized by e or  0 -1 0 -1

  8. VII. Types of Radiation – Gamma rays • Gamma rays are high energy radiation that possess no mass. • Possess no electrical charge and are not deflected by magnetic or electrical fields. • Not completely blocked by lead or concrete • The most penetrating and damaging type of radiation • Carry no charge • Symbolized by  0 0

  9. IX. Electrostatic Force • Electrostatic force is when like charges repel and opposite charges attract.

  10. X. Strong Nuclear Force • The strong nuclear force or nuclear force is an attractive force that acts between all nuclear particles that are extremely close together. • It keeps the nucleus together.

  11. Remember Mass Number and Atomic Number C 14 6 Mass number Atomic number

  12. XI. Writing and Balancing Nuclear Equations • In a balanced nuclear equation, mass numbers and atomic numbers are conserved. Example • Th  Ra + He • Notice the mass numbers and atomic numbers add up to the same on both sides of the equation 226 88 4 2 230 90

  13. VIII. Electron Capture • Electron capture occurs when a nucleus of an atom draws in an electron. • Rb + e → Kr • Also known as Beta capture 81 37 0 - 1 81 36

  14. Practice • Zr e + ? • Po  He + ? • ?  Rn + He • Ca  e + ? • Cm  He + ? 97 40 0 -1 97 41 Nb 218 84 4 2 214 82 Pb 222 86 4 2 226 88 Ra 0 -1 47 21 47 20 Sc 240 94 Pu 244 96 4 2

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