1 nuclear radiation natural radioactivity nuclear equations producing radioactive isotopes half-life...

Download 1 Nuclear Radiation Natural Radioactivity Nuclear Equations Producing Radioactive Isotopes Half-Life Nuclear Fission and Fusion

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  • Nuclear RadiationNatural RadioactivityNuclear EquationsProducing Radioactive IsotopesHalf-LifeNuclear Fission and Fusion

  • Subatomic ParticlesProtons- plus charge

    In the nucleusNeutrons- neutral

    Electrons - negative charge Outside the nucleus

  • Nuclear SymbolsElement symbolMass number (p+ + no) Atomic number (number of p+)

  • RADIOACTIVITYNuclei of unstable isotopes called radioisotopes gain stability by undergoing changesThese changes are always accompanied by large amounts of energyDiscovery of radioactivity dealt a blow to Daltons theory that atoms are indivisible

  • RadiationRadiation comes from the nucleus of an atom.Unstable nucleus emits a particle or energy alpha beta

    gamma

  • Alpha Particle

    Same as a helium nucleus(He) 4 2 He or

    Two protonsTwo neutrons

  • Beta Particle An electron emitted from the nucleus 0e or 1A neutron in the nucleus breaks down11 0 n H +e 0 1 -1

  • Gamma Radiation Pure radiation

    Like an X-ray but comes from the nucleus

  • Radiation Protection Shieldingalpha paper, clothingbeta lab coat, glovesgamma- lead, thick concreteLimit time exposedKeep distance from source

  • Radiation Protection

  • Balancing Nuclear Equations In the reactants and products

    Atomic numbers must balanceandMass numbers must balance

  • Alpha decay

  • Beta decay

    234Th 234Pa + 0e 90 91 1beta particle

  • Gamma radiationNo change in atomic or mass number

    11B 11B + 0 5 5 0 boron atom in a high-energy state

  • Types of Radioactive Decaygamma ray production (g): positron production : electron capture: (inner-orbital electron is captured by the nucleus)10e

  • Types of Radiation

  • Learning Check NR1Write the nuclear equation for the beta emitter Co-60.

  • Solution NR1Write the nuclear equation for theBeta emitter Co-60.60Co 60Ni + 0 e 27 28 -1

  • Half-Life of a RadioisotopeThe time for the radiation level to fall (decay) to one-half its initial value

    decay curve

    8 mg 4 mg2 mg 1 mg

    initial1 half-life23

  • Examples of Half-LifeIsotope Half lifeC-152.4 secRa-2243.6 daysRa-22312 daysI-12560 daysC-145700 yearsU-235710 000 000 years

  • Learning Check NR3 The half life of I-123 is 13 hr. How much of a 64 mg sample of I-123 is left after 26 hours?

  • Solution NR3t1/2 =13 hrs 26 hours = 2 x t1/2Amount initial =64mg Amount remaining = 64 mg x x = 16 mg

  • Nuclear FissionFissionlarge nuclei break up235U + 1n 139Ba + 94Kr + 3 1n + 92 0 56 36 0

    Energy

  • Fission

  • Nuclear FusionFusion small nuclei combine

    2H + 3H 4He + 1n + 1 1 2 0

    Occurs in the sun and other starsEnergy

  • Learning Check NR4Indicate if each of the following areFission(2) fusion

    Nucleus splits Large amounts of energy releasedSmall nuclei form larger nucleiHydrogen nuclei react

    Energy

  • Solution NR4Indicate if each of the following areFission(2) fusion

    1 Nucleus splits 1 + 2 Large amounts of energy released 2 Small nuclei form larger nuclei 2 Hydrogen nuclei react

  • Energy and MassNuclear changes occur with small but measurable losses of mass. The lost mass is called the mass defect, and is converted to energy according to Einsteins equation: DE = Dmc2 Dm = mass defect DE = change in energy c = speed of lightBecause c2 is so large, even small amounts of mass are converted to enormous amount of energy.

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