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Section 24-1

Section 24.1 Nuclear Radiation. Summarize the events that led to understanding radiation. Identify alpha, beta, and gamma radiations in terms of composition and key properties. Section 24-1. Section 24.1 Nuclear Radiation (cont.). radioisotope X ray penetrating power.

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Section 24-1

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  1. Section 24.1 Nuclear Radiation • Summarize the events that led to understanding radiation. • Identify alpha, beta, and gamma radiations in terms of composition and key properties. Section 24-1

  2. Section 24.1 Nuclear Radiation (cont.) radioisotope X ray penetrating power Under certain conditions, some nuclei can emit alpha, beta, or gamma radiation. Section 24-1

  3. The Discovery of Radiation • Nuclear reactions are different from other types of reactions. • Minerals that emit light after being exposed to sunlight, a phenomenon called phosphorescence. • Nuclear chemistry is concerned with the structure of atomic nuclei and the changes they undergo. • Marie Curie and her husband Pierre isolated the first radioactive materials.

  4. Radioactivity : The process by which materials give off spontaneous emissions “rays” without exposed to the light.

  5. The Discovery of Radiation (cont.) Section 24-1

  6. Types of Radiation • Isotopes are atoms of the same element that have different numbers of neutrons. • Isotopes of atoms with unstable nuclei are called radioisotopes. • Unstable nuclei emit radiation to attain more stable atomic configurations in a process called radioactive decay. • The three most common types of radiation are alpha, beta, and gamma. Section 24-1

  7. Types of Radiation (cont.) Section 24-1

  8. Types of Radiation (cont.) • Alpha particles have the same composition as a helium nucleus24He—two protons and two neutrons. • Because of the protons, alpha particles have a 2+ charge. • Alpha radiation consists of a stream of particles. Section 24-1

  9. Types of Radiation (cont.) • Alpha radiation is not very penetrating—a single sheet of paper will stop an alpha particle. • A radium-226 nucleus undergoes alpha decay to form radon-222 and an alpha particle Section 24-1

  10. What is the number of protons and neutrons in radium-226 and radon-222? Radium-226: 88 protons, 138 neutrons; Radon-222: 86 protons, 136 neutrons

  11. Types of Radiation (cont.) • Beta particles are very fast-moving electrons emitted when a neutron is converted to a proton. n→ p + β • Beta particles have insignificant mass (almost zero) and a 1– charge. Section 24-1

  12. Types of Radiation (cont.) • Beta radiation is a stream of fast moving particles with greater penetrating power—a thin sheet of foil will stop them. • An iodine-131 nucleus undergoes beta decay to form xenon-131 and a beta particle Section 24-1

  13. How does beta decay affect the mass number of the decaying nucleus? • The mass number does not change .

  14. Types of Radiation (cont.) • Gamma rays are high-energy electromagnetic radiation. • Gamma rays (short wavelength) are photons, which are high-energy • Gamma rays have no mass or charge so the emission of gamma rays does not change the atomic number or mass number of a nucleus. • Gamma rays almost always accompany alpha and beta radiation. • X rays are a form of high-energy electromagnetic radiation emitted from certain materials in an excited state. Section 24-1

  15. Q: Compare and contrast X-rays and gamma rays. X-rays are emitted from materials that are in an excited state. Gamma rays are produced by radioactive sources.

  16. Types of Radiation (cont.) • The ability of radiation to pass through matter is called its penetrating power. • Gamma rays are highly penetrating because they have no charge and no mass. Section 24-1

  17. A B C D Section 24.1 Assessment Why do radioisotopes emit radiation? A.to balance charges in the nucleus B.to release energy C.to attain more stable atomic configurations D.to gain energy Section 24-1

  18. A B C D Section 24.1 Assessment X rays are most similar to what type of nuclear emissions? A.gamma rays B.alpha particles C.beta particles D.delta waves Section 24-1

  19. Q1: List the different types of radiation and their charges. • alpha (2+), beta (1-), and gamma (0) • Q2: Compare the subatomic particles involved in nuclear and chemical reactions. • Protons, electrons, and neutrons can be involved in nuclear change; only electrons are involved in chemical change.

  20. Q3: Explain how you know whether the reaction is chemical or nuclear when an atom undergoes a reaction and attains a more-stable form. • If the new, more stable form of the atom has an identity different from the original atom, a nuclear process has occurred.

  21. A B C D Which statement is NOT true of beta particles? A.They have the same mass as an electron. B.They have a charge of 1+. C.They are less penetrating than alpha particles. D.They are represented by 0-1β. STP 1

  22. End of section 24.1

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