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UI CHEM 1120 - Chemical Reactions vs. Nuclear

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CHEM 1120 1st Edition Lecture 9Outline of Last Lecture 1. Cell theory2. How we study cells3. Common features of cells4. Prokaryotic cells features5. Eukaryotic cells featuresOutline of Current Lecture 1. Chemical Reactions vs. Nuclear 2. Radioactivity3. Balancing Nuclear 4. Types of Emissions 5. Nuclear Stability Current LectureChapter 21 Nuclear Chemistry- Energy: Chemical vs. Nuclearo Chemical energy associated with making and breaking chemical bondso Nuclear energy Is enormous in comparisono Nuclear energy due to changes in nucleus of atoms, changing them into different atomso 13% worldwide energy comes from nuclear energy- Chemical ReactionsThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.o Atoms never change identityo Chemical bonds break and form with changes in distribution of orbital electrons. Nuclearparticles do not take parto Small changes in energy and immeasurable change of masso Reaction rates are sensitive to reactants, temperature, reactant concentration, and catalysis- Nuclear reactiono Atoms of one element typically convert into atoms of another elemento Protons, neutrons, and other elementary particles are involved. Orbital electrons rarely take parto Large changes in energy and measurable mass changes occuro Reaction rates affected by number of nuclei, not by reactant, temp, concentrations, and catalysis 12.1 Radioactivity=the spontaneous emission of particles or radiation from atomic nuclei - A stable nucleus remains intact indefinitely but great majority of nuclei are unstable- An unstable nucleus exhibits radioactivity, it spontaneously disintegrates or decays- Protons and neutrons:o Elementary particles that make up the nucleus are collectively called nucleons- Nuclideo Nucleus with a particular composition of mass number and atomic number- Nucleono A proton or neutron - Radionuclideo A nuclide that is radioactive- Radioisotope o An atom containing a radionuclide - X=symbol for element- Z=charge of particle (number of protons)- A=mass number (mass #)- sum of nucleons (protons and neutrons)Balancing Nuclear Equations- In an equation, atoms and charges need to balance- Atomic number and mass number need to balance.- When nuclide decays, forms a nuclide of lower energy and the excess energy is carried off by theemitted radiationo The decaying or reactant nuclide is called the parento The product nuclide is called the daughter - REACTANTS(TOTAL A & Z)=PRODUCTS(TOTAL A & Z)Types of Emissions (Radiated emitted by a radionuclide)- Radioactive decay is when a nuclide of one element spontaneously decays into a nuclide of a different element - Three common types of emission radiationo Alphao Betao Gamma- Types of Radioactive decayo Alpha  Loss of an alpha particle from a nucleus  For each particle emitted, A decreases by 4 and Z decreases by 2. Every element heavier than Pb (Z=82), as well as a few lighter ones exhibits alpha decayo Beta Involves the ejection from a beta particle from the nucleus Conversion of a neutron into a proton, which remains in the nucleus and a beta particle which is expelled immediately o Positron Involves the emission of a positron from a nucleus Positron is the antiparticle of an electron. Involves the conversion of a proton into a neutron.o Electron capture Occurs when the nucleus of an atom draws in an electron from an orbital of the lowest energy level Involves conversion of a proton into a neutrono Gamma  Involves the radiation of high-energy gamma photons from an excited nucleus.21.2 Patterns of Nuclear Stability- Why only some isotopes radioactive?o For smaller nuclei (Z is smaller than or equal to 20), stable nuclei have a neutron-to-protons ratio close to 1:1o As nuclei get larger, it take a larger number of neutrons to stabilize the nucleuso 265 isotopes are stable all lie in a belt of stabilityo Nuclei with > 83 protons are all radioactiveo Magic numbers- nuclei with 2,8,20,28,50, or 82 protons or neutrons are


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