Slide 1Lightning ReviewModern understanding: the ``onion’’ pictureSlide 4Slide 5Introduction: Development of Nuclear Physics29.1 Some Properties of NucleiCharge and massSummary of MassesQuick problem: protons in your bodyThe Size of the NucleusSize of NucleusDensity of NucleiNuclear StabilityNuclear Stability chartIsotopes29.2 Binding EnergyProblem: binding energySlide 19Binding Energy Notes29.3 RadioactivityDistinguishing Types of RadiationPenetrating Ability of ParticlesThe Decay ConstantDecay CurveUnitsWhat fraction of a radioactive sample has decayed after two half-lives have elapsed? (a) 1/4 (b) 1/2 (c) 3/4 (d) not enough information to say1101/13/1901/13/19General Physics (PHY 2140)Lecture 36Lecture 36 Modern PhysicsNuclear PhysicsNuclear propertiesBinding energyRadioactivityChapter 29http://www.physics.wayne.edu/~apetrov/PHY2140/2201/13/1901/13/19Lightning ReviewLightning ReviewLast lecture: 1.1.Atomic physicsAtomic physicsThe exclusion principle and periodic tableThe exclusion principle and periodic tableAtomic transitions, lasersAtomic transitions, lasersReview Problem: Why do lithium, potassium, and sodium exhibit similar chemical properties?2 , 1, 2,3,...r n np l= =, 1, 2,3,...em vr n n= =h2 21 1 1Hf iRn nl� �= -� �� �� �3301/13/1901/13/19Modern understanding: the ``onion’’ pictureModern understanding: the ``onion’’ pictureLet’s see what’s inside!Atom4401/13/1901/13/19Modern understanding: the ``onion’’ pictureModern understanding: the ``onion’’ pictureLet’s see what’s inside!Nucleus5501/13/1901/13/19Modern understanding: the ``onion’’ pictureModern understanding: the ``onion’’ pictureLet’s see what’s inside!Protons and neutronsNext chapter…6601/13/1901/13/19Introduction: Development of Nuclear PhysicsIntroduction: Development of Nuclear Physics18961896 – the birth of nuclear physics – the birth of nuclear physicsBecquerel discovered radioactivity in uranium compoundsBecquerel discovered radioactivity in uranium compoundsRutherford showed the radiation had three typesRutherford showed the radiation had three typesAlpha (He nucleus)Alpha (He nucleus)Beta (electrons)Beta (electrons)Gamma (high-energy photons)Gamma (high-energy photons)19111911 Rutherford, Geiger and Marsden performed scattering experiments Rutherford, Geiger and Marsden performed scattering experiments Established the point mass nature of the nucleusEstablished the point mass nature of the nucleusNuclear forceNuclear force was a new type of force was a new type of force19191919 Rutherford and coworkers first observed nuclear reactions in which Rutherford and coworkers first observed nuclear reactions in which naturally occurring alpha particles bombarded nitrogen nuclei to produce naturally occurring alpha particles bombarded nitrogen nuclei to produce oxygenoxygen19321932 Cockcroft and Walton first used artificially accelerated protons to Cockcroft and Walton first used artificially accelerated protons to produce nuclear reactionsproduce nuclear reactions19321932 Chadwick discovered the neutron Chadwick discovered the neutron19331933 the Curies discovered artificial radioactivity the Curies discovered artificial radioactivity19381938 Hahn and Strassman discovered nuclear fission Hahn and Strassman discovered nuclear fission19421942 Fermi achieved the first controlled nuclear fission reactor Fermi achieved the first controlled nuclear fission reactor7701/13/1901/13/1929.1 Some Properties of Nuclei29.1 Some Properties of NucleiAll nuclei are composed of protons and neutronsAll nuclei are composed of protons and neutronsException is ordinary hydrogen with just a protonException is ordinary hydrogen with just a protonThe The atomic numberatomic number, Z, equals the number of protons in the nucleus, Z, equals the number of protons in the nucleusThe The neutron numberneutron number, N, is the number of neutrons in the nucleus, N, is the number of neutrons in the nucleusThe The mass numbermass number, A, is the number of nucleons in the nucleus, A, is the number of nucleons in the nucleusA = Z + NA = Z + NNucleon is a generic term used to refer to either a proton or a neutronNucleon is a generic term used to refer to either a proton or a neutronThe mass number is not the same as the massThe mass number is not the same as the massNotationNotationExample:Example: Mass number is 27Mass number is 27Atomic number is 13Atomic number is 13Contains 13 protonsContains 13 protonsContains 14 (27 – 13) neutronsContains 14 (27 – 13) neutronsThe Z may be omitted since the element can be used to determine ZThe Z may be omitted since the element can be used to determine ZXAZ where X is the chemical symbol of the elementwhere X is the chemical symbol of the elementAl27138801/13/1901/13/19Charge and massCharge and massCharge:Charge:The electron has a single negative charge, -e (The electron has a single negative charge, -e (e = 1.60217733 x 10e = 1.60217733 x 10-19-19 C C))The proton has a single positive charge, +e The proton has a single positive charge, +e Thus, charge of a nucleus is equal to ZeThus, charge of a nucleus is equal to ZeThe neutron has no chargeThe neutron has no chargeMakes it difficult to detectMakes it difficult to detect Mass:Mass:It is convenient to use It is convenient to use atomic mass units,atomic mass units, u, to express masses u, to express masses1 u = 1.660559 x 101 u = 1.660559 x 10-27-27 kg kgBased on definition that the Based on definition that the mass of one atom of C-12 is exactly 12 umass of one atom of C-12 is exactly 12 uMass can also be expressed in MeV/cMass can also be expressed in MeV/c22From EFrom ERR = m c = m c221 u = 931.494 MeV/c1 u = 931.494 MeV/c229901/13/1901/13/19Summary of MassesSummary of MassesMassesParticlekgkguuMeV/cMeV/c22Proton1.6726 x 101.6726 x 10-27-271.0072761.007276938.28938.28Neutron1.6750 x 101.6750 x 10-27-271.0086651.008665939.57939.57Electron9.101 x 109.101 x 10-31-315.486x105.486x10-4-40.5110.511101001/13/1901/13/19What is the order of magnitude of the number of protons in your body? Of the number of neutrons? Of the number of electrons? Take your mass approximately equal to 70 kg.Quick problem: protons in your bodyQuick problem: protons in your bodyAn iron nucleus (in hemoglobin) has a few more neutrons than protons, but in a typical water molecule there are eight neutrons and ten protons. So protons