radioactivity and nuclear energy

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Radioactivity and Nuclear Energy. Chapter 19. http://www.youtube.com/watch?v=PEHcHcneFFc&feature=related. Chemical vs. Nuclear. Chemical Reactions. Nuclear Reactions. Involve nuclei changes Can involve e-, p+, and n o Convert 1 element to another element LARGE energy changes. - PowerPoint PPT Presentation

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  • Radioactivity and Nuclear EnergyChapter 19http://www.youtube.com/watch?v=PEHcHcneFFc&feature=related

  • Chemical vs. NuclearChemical ReactionsBreak and form bondsCreated with valence electronsType of elements do not change during the reactionSmall energy changesNuclear ReactionsInvolve nuclei changesCan involve e-, p+, and noConvert 1 element to another elementLARGE energy changes

  • Facts about the NucleusThe nucleus is composed of nucleons: Neutrons and protons

  • Isotopes and NuclidesIsotopes: atoms that have identical atomic numbers but different mass numbersHow are they similar? How are they different?

  • RadioactivityRadioactivity the result of the spontaneous decomposition of an unstable nucleus. Includes the production of high energy particles that make the nucleus more stable.

  • Radioactive Isotopes85% of the 2000 known isotopes are radioactive.279 of those 2000 are not radioactivePercent abundance of isotopes is much smaller.Not radioactive: C-12 99% of all CRadioactive: C-14 < 0.1%

    Chart1

    85

    15

    Percent of isotopes that are radioactiv Percent of isotopes that are NOT radioactive

    Sheet1

    Percent of isotopes that are radioactiv85

    Percent of isotopes that are NOT radioactive15

    Sheet1

    Percent of isotopes that are radioactiv Percent of isotopes that are NOT radioactive

    Sheet2

    Sheet3

  • How do we know if a nucleus is stable?Protons and neutrons are nucleonsHeld together by strong nuclear force

  • Nuclear StabilityHow can you tell if an element is stable?Look at proton to neutron ratio (p:n)Atomic number less than 20:Want p:n = 1:1

    Above atomic number 20 have more neutrons than protons, which increases the ratio

  • Where are the stable nuclei found?Band of Stability shows where the stable nuclei can be foundDepends on the proton to neutron ratioLocation determines the type of decay for the isotope

  • How can I become a stable nucleus?1. Alpha RadiationHelium nuclei are emitted from a radioactive source

    Called alpha particlesContain two protons and two neutronsOverall positive charge

    U ThHe

  • How can I become a stable nucleus?2. Beta RadiationFast-moving electrons created by the break-down of a neutron in an atom

    Called beta particles

    CNe-

  • How can I become a stable nucleus?3. Gamma RadiationHigh-energy electromagnetic radiation given off by a radioisotopeOften given-off along with alpha or beta radiationHave no mass or charge

  • How can I become a stable nucleus?4. positron emissionPositron :has same mass as an electron but the opposite chargeCreated when a proton breaks apart to create a neutron and positron

    BBee+

  • How can I become a stable nucleus?Electron captureCapture an inner electron and turn it into a protonHand of God

  • Practice timePractice WS with isotopic notation and what ratio you have for Neutron to proton and types of decay due tomorrow!!!

    Beaker and bunsen video*Not gunna talk about T, P and catalysts cuz its that both sides may or may not be affected by this so its not really a distinction*atomic number (Z)= Number of protons

    mass number (A) = Sum of the numbers of neutrons and protons

    **All have six protons (Z=6), and they have 6, 7, and 8 neutrons

    *Radioactivity is spontaneous unlike nuclear fission. It cant be turned off and on. It occurs at its own rate outside of our control.*% abundance is much, much smaller.C-12 99% of all CC-14 < 0.1%Show island of stability video clip where they talk about this2 protons repel eachotherProton to neutron is no repulsionN to n = no repulsionN to P and N to N have a strong nuclear force so the addition of all these nuclear forces is what holds the nucleus together

    BUT more neutrons = less repulsions so the nucleus can be more stable**Example -= lead 206 (with 82p+) is stable cuz its ratio is 1.51:1 so its close to 3:2 which is 1.5:1As you get bigger atoms you have more p so you need more n to increase the nucelar force so outweigh the strong p repulsion*Outside the band you will be radioactive and do decay until you can get in the bandWe see the band ends after lead -208 cuz after that there is no band cuz all things are radioactive*Go with alpha and beta decay and they are the main source of energy loss in nuclear decay*Go with alpha and beta decay and they are the main source of energy loss in nuclear decay*Draw pic with Ni-59 grabbing an inner electron to turn-into Co-59*

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