Chapter 22.2 : Radioactive Decay
- 1. Chapter 22.2
- 2. 1. Define and relate the terms radioactive decay and nuclear radiation. 2. Describe the different types of radioactive decay and their effects on the nucleus. 3. Define the term half-life, and explain how it relates to the stability of a nucleus. 4. Define and relate the terms decay series, parent nuclide, and daughter nuclide. 5. Explain how artificial radioactive nuclides are made, and discuss their significance.
- 3. • Radioactive decay is the spontaneous disintegration of a nucleus into a slightly lighter nucleus, accompanied by emission of particles, electromagnetic radiation, or both. • Nuclear radiation is particles or electromagnetic radiation emitted from the nucleus during radioactive decay. • An unstable nucleus that undergoes radioactive decay is a radioactive nuclide. • All of the nuclides beyond atomic number 83 are unstable and thus radioactive.
- 4. • A nuclide’s type and rate of decay depend on the nucleon content and energy level of the nucleus. • Alpha Emission • An alpha particle (α) is two protons and two neutrons bound together and is emitted from the nucleus during some kinds of radioactive decay. 4 2He • Alpha emission is restricted almost entirely to very heavy nuclei.
- 5. 4 2He
- 6. •Beta Emission • A beta particle (β) is an electron emitted from the nucleus during some kinds of radioactive decay. • To decrease the number of neutrons, a neutron can be converted into a proton and an electron. 0 -1n p + β1 1 0 1 • The atomic number increases by one and the mass number stays the same.
- 7. •Positron Emission • A positron is a particle that has the same mass as an electron, but has a positive charge, and is emitted from the nucleus during some kinds of radioactive decay. • To decrease the number of protons, a proton can be converted into a neutron by emitting a positron. 0 +1p n + β1 1 1 0 • The atomic number decreases by one and the mass number stays the same.
- 8. •Electron Capture • In electron capture, an inner orbital electron is captured by the nucleus of its own atom. • To increase the number of neutrons, an inner orbital electron combines with a proton to form a neutron. 0 -1e + n1 1 1 0p • The atomic number decreases by one and the mass number stays the same.
- 9. • Gamma Emission • Gamma rays () are high-energy electromagnetic waves emitted from a nucleus as it changes from an excited state to a ground energy state.
- 11. • Half-life, t1/2, is the time required for half the atoms of a radioactive nuclide to decay. • Each radioactive nuclide has its own half-life. • More-stable nuclides decay slowly and have longer half-lives.
- 15. Phosphorus-32 has a half-life of 14.3 days. How many milligrams of phosphorus-32 remain after 57.2 days if you start with 4.0 mg of the isotope? Given: original mass of phosphorus-32 = 4.0 mg half-life of phosphorus-32 = 14.3 days time elapsed = 57.2 days Unknown: mass of phosphorus-32 remaining after 57.2 days Solution: 1 half -life number of half -lives time elapsed (days) 14.3 days amount of phosphorus - 32 remaining 1 original amount of phosphorus - 32 for each half -life 2
- 16. 1 half -life number of half -lives 52.7 days 4 half -lives 14.3 days amount of phosphorus - 32 remaining 1 1 1 1 4.0 mg 2 2 .2 2 2 0 5 mg
- 17. • A decay series is a series of radioactive nuclides produced by successive radioactive decay until a stable nuclide is reached. • The heaviest nuclide of each decay series is called the parent nuclide. • The nuclides produced by the decay of the parent nuclides are called daughter nuclides.
- 19. • Artificial radioactive nuclides are radioactive nuclides not found naturally on Earth. • They are made by artificial transmutations, bombardment of nuclei with charged and uncharged particles. • Transuranium elements are elements with more than 92 protons in their nuclei. • Artificial transmutations are used to produce the transuranium elements.
- 20. In Illinois
- 21. Dark Matter