200 likes | 287 Views
Nuclear Reactions. Chapter 10. Standards. SPS3 . Students will distinguish the characteristics and components of radioactivity SPS3a . Differentiate among alpha and beta particles and gamma radiation . SPS3b . Differentiate between fission and fusion .
E N D
Nuclear Reactions Chapter 10
Standards • SPS3. Students will distinguish the characteristics and components of radioactivity • SPS3a. Differentiate among alphaandbeta particles and gamma radiation. • SPS3b. Differentiate between fissionand fusion. • SPS3c. Explain the process half-life as related to radioactive decay. • SPS3d. Describe nuclear energy, its practical application as an alternative energy source, and its potential problems.
Nuclear Radiation Radioactive Decay: unstable isotopes emit particles and release energy to become stable isotopes. • after radioactive decay, the element changes into a different isotope of the same element orinto an entirely different element.
Radiation Nuclear Radiation: particles and energy released from the nucleus during radioactive decay.
Types of Radiation • Alpha () -protons and neutrons paper 2+ • Beta-minus (-) • -electrons and positrons lead 1- • Gamma () • -high-energy photons concrete 0
Nuclear Decay • Anytime an unstable nucleus emits alpha or beta particles, the number of protons and neutrons changes. • Alpha decay: atomic mass and number change • Beta decay: atomic number changes • Gamma decay: energy of the nucleus is lower, but no change in atomic number or mass
Nuclear Decay • Why nuclide (nucleus of an isotope) decay… to obtain a stable ratio of neutrons to protons Stable Unstable (radioactive)
Ra Rn + He 226 222 4 88 86 2 Alpha Decay 226 = 222 + 4 88 = 86 + 2 (atomic mass & atomic number change)
C C + e 14 14 0 6 7 -1 Beta Decay Equations 14 = 14 + 0 6 = 7 + (-1) (atomic mass stays the same; atomic number changes by 1)
+ 227 X Ac He A 4 89 2 Z Actinium-217 decays by releasing an alpha particle. Write the equation for this decay process and determine which element is formed.
+ 63 Ni X e A 0 28 -1 Z Complete the following radioactive-decay equation. Identify the isotope X. Indicate whether alpha or beta decay takes place.
Radioactive Decay Rates • Half-life: time in which halfof a radioactive substance decays; measure of how quickly a substance decays. -Iodine-131: used by doctors to diagnose medical problems -Potassium-40: used by geologists to predict the age of rocks
1 One half life 1/2 Two half lives 1/4 Three half lives 1/8 Calculating Half-Life • Radium-226 has a half-life of 1599 years. How long will 7/8 of a sample take to decay? • Find out how much will be left. • 8/8 - 7/8 = 1/8 left over 2. Calculate how many half-lives until only 1/8 is left. 3. Calculate how many years it will take for 3 half lives to occur. 1599 x 3 = 4797 years
Nuclear Fission • Nuclear fission: the process by which a nucleus splits and neutrons and energy are released. • Nuclear chain reaction: a continuous series of fission reactions(pg 340)
Nuclear Fusion • Nuclear fusion: when 2 light nuclei combine to form a heavier nuclei -Hydrogen is turned into Helium on the sun. (pg 342)
Radiation on Earth • All around you. • Background radiation: arises naturally from the sun, soil, rocks, and plants • You are exposed to more radiation in the mountains than at sea level
Beneficial Uses of Radiation • Smoke detectors release alpha particles • Radiation is used in x rays, MRIs, CT scans, PET scans, and ultrasounds • Radiation therapy is used to treat cancer • Used in agriculture to track the flow of water
Nuclear Radiation Risks • High levels of radiation exposure can cause radiation sickness • High concentrations of radon gas can cause cancer