141 Views

Download Presentation
##### Chapter 21

**An Image/Link below is provided (as is) to download presentation**

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.

- - - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - - -

**Chapter 21**Nuclear chemistry**Particles**• α alpha particle 4He a helium nuclei • β beta particle…an electron 0e • -1 • γ gamma particle, no mass, no charge 2p + 2n & NO electrons!**Proton 1H or 1p**• Neutron 1n • Positron 00e • +1**Alpha emission**• Beta emission • Gamma emission**Positron emission**• Electron capture • OR (K-capture) Decay = decomposition**p 2e-) 8e-) 8e-) 2e-)**• K L M N O P …… p+ n**New Zealand currency –**• Ed Hillary, • Kate Sheppard, • QEII, • ApiranaNgata, • Ernest Rutherford -**Nuclear equations**Decay = decomposition**p. 899**Belt of stability**Subatomic Particles**• Particle • Charge • Mass (g) • Nomenclature • alpha • 2+ • 6.64e-24 • 42He 42α • beta • 1- • 6.64e-24 • 0-1e 0-1β • gamma • 0 • 0 • 00γ • proton • 1+ • 6.64e-24 • 11H 11p • neutron • 0 • 6.64e-24 • 0n • elelctron • 1- • 9.11e-28 • 0-1e • positron • 1+ • 9.11e-28 • 0+1e**Other Considerations**• Other Factors to Nuclear Stability• Magic numberProtons with - 2, 8, 20, 28, 50 or 82Neutrons with - 2, 8, 20, 28, 50, 82 or 126• Nuclei with even # of protons and neutrons more stable than with any odd number of protons and neutrons.**• Magic number correspond to filled, closed-shell nucleon**configuration.• Pairs of protons and neutrons analogous to pair of electrons in the atom.**First order decay**• t 1/2 = .693/k • ln([A]o/[A]t) = kt**Shroud**• Of • Turin**Nuclear Binding Force**• Mass defect - Difference between mass the nucleus and the masses of nucleon.Binding Energy - The energy required to separate a nucleus into its nucleons.E=mc2 → E(binding energy) = m(mass defect) c2**Mass of nuclei < ∑mass nucleons Mass of helium nucleus**= 4.00150 amuMass of ∑nucleons = 4.03190 amuMass defect = 0.03040 amu (Binding Energy)**Average binding Energy per nucleon increases to a maximum at**a mass of 50 to 60 and decreases slowly thereafter. Fusion (bring nuclei together) is exothermic for low mass number and fission (splitting of nuclei) is exothermic for high mass number.**Nuclear Fission**• Splitting of heavy nuclei is exothermic for large mass numberIn a nuclear Fission Process:• Neutrons move slowly because it is absorb by the nucleus.• 235U nucleus split into different daughter nuclei and 3.5•1011 J / nucleus• Every 235U nucleus produced 2.4 neutrons.**Each neutron produced can cause fission to another 235U•**Number of fission and energy increase rapidly.• Eventually a chain reaction forms and without control an explosion.**Nuclear Equation: The process**• Radionuclides - spontaneously emit particles and radiation which can be expressed by a nuclear equationSpontaneous Emission: Mass and charge are conserved.**Three quarks for Muster Mark!**• Sure he has not got much of a bark • And sure any he has it's all beside the mark. • —James Joyce, FinnegansWake.