Nuclear Chemistry. 23.1 Nuclear Reactions vs. Normal Chemical Changes Nuclear reactions involve the nucleusNuclear reactions involve the nucleus The

Download Nuclear Chemistry. 23.1 Nuclear Reactions vs. Normal Chemical Changes Nuclear reactions involve the nucleusNuclear reactions involve the nucleus The

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<ul><li> Slide 1 </li> <li> Nuclear Chemistry </li> <li> Slide 2 </li> <li> 23.1 </li> <li> Slide 3 </li> <li> Nuclear Reactions vs. Normal Chemical Changes Nuclear reactions involve the nucleusNuclear reactions involve the nucleus The nucleus opens, and protons and neutrons are rearrangedThe nucleus opens, and protons and neutrons are rearranged The opening of the nucleus releases a tremendous amount of energy that holds the nucleus together called binding energyThe opening of the nucleus releases a tremendous amount of energy that holds the nucleus together called binding energy Normal Chemical Reactions involve electrons, not protons and neutronsNormal Chemical Reactions involve electrons, not protons and neutrons </li> <li> Slide 4 </li> <li> I.Nuclear Chemistry A.Wilhem Rontgen - discovered x-rays in 1895 B.Antoine Henri Becquerl - discovered radioactivity 1.photographic plates and rocks C.Marie and Pierre Curie - discovered other radioactive elements 1.Marie first person to win the Nobel peace prize twice </li> <li> Slide 5 </li> <li> 2.husband run over by wagon when he was crossing the street 3.Marie and her children died of radiation poisoning </li> <li> Slide 6 </li> <li> Radioactivity One of the pieces of evidence for the fact that atoms are made of smaller particles came from the work of Marie Curie (1876-1934).One of the pieces of evidence for the fact that atoms are made of smaller particles came from the work of Marie Curie (1876-1934). She discovered radioactivity, the spontaneous disintegration of some elements into smaller pieces.She discovered radioactivity, the spontaneous disintegration of some elements into smaller pieces. </li> <li> Slide 7 </li> <li> II.Radioactivity A.Spontaneous break down of an unstable nucleus withthe release of particles and rays B. Mass defect and nuclear stability 1. the sum of the particles(protons, neutrons and electrons) that make up an atom but does not add up to the mass of an atom 2. the difference between the sum of the masses and the atomic mass is know as the mass defect </li> <li> Slide 8 </li> <li> Mass Defect Some of the mass can be converted into energySome of the mass can be converted into energy Shown by a very famous equation!Shown by a very famous equation! E=mc 2 EnergyMass Speed of light </li> <li> Slide 9 </li> <li> C.Nuclear binding energy 1.The energy released when a nucleus is formed from nucleons (protons and neutrons) </li> <li> Slide 10 </li> <li> IIIProperties of Radioactive elements 1.They affect photographic film 2.They produce electric charges in the surrounding air 3. They produce fluorescence with certain compounds a.fluorescence - makes thing glow </li> <li> Slide 11 </li> <li> 4. Their radiations have special physiological effects a. causes mutations in cells - changes in the DNA of cells causing rapid growth and a change in their function 5.They undergo radioactive decay a.Radioactive decay - they emit particles from the nucleus making simpler atoms i.half-life - the time it takes 1/2 a given amount to decay ii. Half-lives can be from a few seconds to millions of years </li> <li> Slide 12 </li> <li> Half-Life HALF-LIFE is the time that it takes for 1/2 a sample to decompose.HALF-LIFE is the time that it takes for 1/2 a sample to decompose. The rate of a nuclear transformation depends only on the reactant concentration.The rate of a nuclear transformation depends only on the reactant concentration. </li> <li> Slide 13 </li> <li> Kinetics of Radioactive Decay For each duration (half-life), one half of the substance decomposes. For example: Ra-234 has a half-life of 3.6 days If you start with 50 grams of Ra-234 After 3.6 days &gt; 25 grams After 7.2 days &gt; 12.5 grams After 10.8 days &gt; 6.25 grams </li> <li> Slide 14 </li> <li> Half-Life Decay of 20.0 mg of 15 O. What remains after 3 half-lives? After 5 half-lives? </li> <li> Slide 15 </li> <li> e.g. The half-life of Plutonium -239 is 24110 years. Of an original mass of 100. g, how much remains after 96440 years first find the number of half-life's # Half-lifes = 96440 years 24110 Years = 4 now divide the gram sample in 1/2 four times 100===&gt; 6.25===&gt;12.5===&gt; 25===&gt; 50 1 2 3 4 </li> <li> Slide 16 </li> <li> The half-life of thorium -227 is 18.72 days. How many days are required for 3/4 of a given amount to decay 1 ===&gt; 1/2 ===&gt; 1/4 This tells you that you have 1/4 of the original amount left - therefore - 3/4 of a given amount has decayed you must multiply 18.72 days by 2 == 37.44 days 18.72 days </li> <li> Slide 17 </li> <li> e.gExactly 1/16 of a given amount of protactinium-234 remains after 26.76 hours. What is the half-life of protactinium - 234 First find the number of half-life's 1 ==&gt; 1/2 ===&gt; 1/4 ===&gt; 1/8 ===&gt; 1/16 You must pass threw 4 half lifes 26.76 hours 4 half-lifes = 6.69 hours/half-life </li> <li> Slide 18 </li> <li> The half life of I-123 is 13 hr. How much of a 64 mg sample of I-123 is left after 78 hours? </li> <li> Slide 19 </li> <li> Nuclear Stability Certain numbers of neutrons and protons are extra stable n or p = 2, 8, 20, 50, 82 and 126 Like extra stable numbers of electrons in noble gases (e - = 2, 10, 18, 36, 54 and 86) Nuclei with even numbers of both protons and neutrons are more stable than those with odd numbers of neutron and protons All isotopes of the elements with atomic numbers higher than 83 are radioactive All isotopes of Tc and Pm are radioactive 23.2 </li> <li> Slide 20 </li> <li> Band of Stability and Radioactive Decay When the number of protons in a stable nuclei is plotted against the number of neutrons </li> <li> Slide 21 </li> <li> Stability of Nuclei Out of &gt; 300 stable isotopes: Even Odd Odd Even Z N 15752 505 31 15 P 19 9 F 2 1 H, 6 3 Li, 10 5 B, 14 7 N, 180 73 Ta </li> <li> Slide 22 </li> <li> Radioactive decay 1.types of particles a.alpha particles, contain two protons and two neutrons - can be stopped by a piece of paper - have low penetrating power - may cause burns to the flesh b.beta particles, , high speed electrons, travel at close to the speed of light, c, which is equal to 3 x 10 8 m/sec or 186,000 miles a sec c.gamma rays, , are high energy electromagnetic waves. Most penetrating </li> <li> Slide 23 </li> <li> Types of Radiation Alpha a positively charged (+2) helium isotope - we usually ignore the charge because it involves electrons, not protons and neutrons Alpha a positively charged (+2) helium isotope - we usually ignore the charge because it involves electrons, not protons and neutrons Beta an electronBeta an electron Gamma pure energy; called a ray rather than a particleGamma pure energy; called a ray rather than a particle </li> <li> Slide 24 </li> <li> Other Nuclear Particles Neutron Neutron Positron a positive electron Positron a positive electron Proton usually referred to as hydrogen-1Proton usually referred to as hydrogen-1 Any other elemental isotopeAny other elemental isotope </li> <li> Slide 25 </li> <li> Penetrating Ability </li> <li> Slide 26 </li> <li> X A Z Mass Number Atomic Number Element Symbol Atomic number (Z) = number of protons in nucleus Mass number (A) = number of protons + number of neutrons = atomic number (Z) + number of neutrons A Z 1p1p 1 1H1H 1 or proton 1n1n 0 neutron 0e0e 00 or electron 0e0e +1 00 or positron 4 He 2 44 2 or particle 1 1 1 0 0 0 +1 4 2 23.1 </li> <li> Slide 27 </li> <li> 3.radioactive decay sequence 238 U 92 ----&gt; + 234 Th 90 parent daughter when you have an alpha ejection - you lose 2 protons and 2 neutron The 92 of uranium is the number of protons and will go to 90 with an alpha ejection - the number of protons in you nucleus determines the element. </li> <li> Slide 28 </li> <li> Slide 29 </li> <li> therefore - U turns into Th The 238 of U is the total number of particles in the nucleus = number of protons and neutrons - with an alpha ejection - you lose 2 protons and 2 neutrons your mass goes down by 4 or become 234 226 Ra 88 ----&gt; + 222 Rn 86 </li> <li> Slide 30 </li> <li> When you have a beta ejection - you have a neutron change to a protons thus causing your number of protons to go up by one. The total number of particles in the nucleus does not change 234 Pa 91 ----&gt; 234 U 92 + beta particle 234 Th 90 ----&gt; 234 Pa 91 + </li> <li> Slide 31 </li> <li> Slide 32 </li> <li> On page 724 do problems 33,34,35,40,41,42,43 </li> <li> Slide 33 </li> <li> 212 Po decays by alpha emission. Write the balanced nuclear equation for the decay of 212 Po. 4 He 2 44 2 or alpha particle - 212 Po 4 He + A X 84 2Z 212 = 4 + AA = 208 84 = 2 + ZZ = 82 212 Po 4 He + 208 Pb 84 282 23.1 </li> <li> Slide 34 </li> <li> Nuclear Stability and Radioactive Decay Beta decay 14 C 14 N + 0 + 6 7 40 K 40 Ca + 0 + 19 20 1 n 1 p + 0 + 0 1 Decrease # of neutrons by 1 Increase # of protons by 1 Positron decay 11 C 11 B + 0 + 6 5 +1 38 K 38 Ar + 0 + 19 18 +1 1 p 1 n + 0 + 1 0 +1 Increase # of neutrons by 1 Decrease # of protons by 1 and have A = 0 and Z = 0 23.2 </li> <li> Slide 35 </li> <li> Electron capture decay Increase # of neutrons by 1 Decrease # of protons by 1 Nuclear Stability and Radioactive Decay 37 Ar + 0 e 37 Cl + 18 17 55 Fe + 0 e 55 Mn + 26 25 1 p + 0 e 1 n + 1 0 Alpha decay Decrease # of neutrons by 2 Decrease # of protons by 2 212 Po 4 He + 208 Pb 84 282 Spontaneous fission 252 Cf 2 125 In + 2 1 n 98 490 23.2 </li> <li> Slide 36 </li> <li> What radioactive isotope is produced in the following bombardment of boron? 10 B + 4 He ? + 1 n 5 2 0 </li> <li> Slide 37 </li> <li> What radioactive isotope is produced in the following bombardment of boron? 10 B + 4 He 13 N + 1 n 5 2 7 0 </li> <li> Slide 38 </li> <li> Write Nuclear Equations! Write the nuclear equation for the beta emitter Co-60. 60 Co 0 e+ 60 Ni 27 -128 </li> <li> Slide 39 </li> <li> Positron emission -conversion of a proton to a neutron by the emission of a positron 1.Positron - particle that has the same mass as an electron, but has a positive charge Gamma radiation - does not change the identity of the element but makes the atom more stable Transmutation - changing the identity of an element through the release of radioactive particles Isotopes - atoms of the same element that have different number of neutrons </li> <li> Slide 40 </li> <li> Geiger-Mller Counter 23.7 </li> <li> Slide 41 </li> <li> Geiger Counter Used to detect radioactive substances </li> <li> Slide 42 </li> <li> Artificial Nuclear Reactions New elements or new isotopes of known elements are produced by bombarding an atom with a subatomic particle such as a proton or neutron -- or even a much heavier particle such as 4 He and 11 B. Reactions using neutrons are called reactions because a ray is usually emitted. Radioisotopes used in medicine are often made by reactions. </li> <li> Slide 43 </li> <li> Artificial Nuclear Reactions Example of a reaction is production of radioactive 31 P for use in studies of P uptake in the body. 31 15 P + 1 0 n ---&gt; 32 15 P + </li> <li> Slide 44 </li> <li> Transuranium Elements Elements beyond 92 (transuranium) made starting with an reaction 238 92 U + 1 0 n ---&gt; 239 92 U + 239 92 U ---&gt; 239 93 Np + 0 -1 239 93 Np ---&gt; 239 94 Pu + 0 -1 239 93 Np ---&gt; 239 94 Pu + 0 -1 </li> <li> Slide 45 </li> <li> 23.8 Biological Effects of Radiation Radiation absorbed dose (rad) 1 rad = 1 x 10 -5 J/g of material Roentgen equivalent for man (rem) 1 rem = 1 rad x QQuality Factor -ray = 1 = 1 = 20 </li> <li> Slide 46 </li> <li> Effects of Radiation </li> <li> Slide 47 </li> <li> Nuclear Fission Fission is the splitting of atoms These are usually very large, so that they are not as stable Fission chain has three general steps: 1. Initiation. Reaction of a single atom starts the chain (e.g., 235 U + neutron) 2. Propagation. 236 U fission releases neutrons that initiate other fissions 3. Termination. </li> <li> Slide 48 </li> <li> Nuclear Fission </li> <li> Slide 49 </li> <li> 23.5 235 U + 1 n 90 Sr + 143 Xe + 3 1 n + Energy 92 54 3800 Energy = 3.3 x 10 -11 J per 235 U = 2.0 x 10 13 J per mole 235 U Combustion of 1 ton of coal = 5 x 10 7 J = 235 grams= 0.5 lbs </li> <li> Slide 50 </li> <li> Representation of a fission process. </li> <li> Slide 51 </li> <li> Nuclear Fission 23.5 Nuclear chain reaction is a self-sustaining sequence of nuclear fission reactions. The minimum mass of fissionable material required to generate a self-sustaining nuclear chain reaction is the critical mass. Non-critical Critical </li> <li> Slide 52 </li> <li> Nuclear Fission &amp; POWER Currently about 103 nuclear power plants in the U.S. and about 435 worldwide.Currently about 103 nuclear power plants in the U.S. and about 435 worldwide. 17% of the worlds energy comes from nuclear.17% of the worlds energy comes from nuclear. </li> <li> Slide 53 </li> <li> Diagram of a nuclear power plant </li> <li> Slide 54 </li> <li> Annual Waste Production 23.5 35,000 tons SO 2 4.5 x 10 6 tons CO 2 1,000 MW coal-fired power plant 3.5 x 10 6 ft 3 ash 1,000 MW nuclear power plant 70 ft 3 vitrified waste Nuclear Fission </li> <li> Slide 55 </li> <li> Nuclear Fusion Fusion small nuclei combine 2 H + 3 H 4 He + 1 n + 1 1 2 0 Occurs in the sun and other stars Energy </li> <li> Slide 56 </li> <li> Nuclear Fusion Fusion Excessive heat can not be contained Attempts at cold fusion have FAILED. Hot fusion is difficult to contain </li> <li> Slide 57 </li> <li> 23.7 Radioisotopes in Medicine 1 out of every 3 hospital patients will undergo a nuclear medicine procedure 24 Na, t = 14.8 hr, emitter, blood-flow tracer 131 I, t = 14.8 hr, emitter, thyroid gland activity 123 I, t = 13.3 hr, ray emitter, brain imaging 18 F, t = 1.8 hr, emitter, positron emission tomography 99m Tc, t = 6 hr, ray emitter, imaging agent Brain images with 123 I-labeled compound </li> <li> Slide 58 </li> <li> protection from radiation A.Shielding sunscreen, lead apron B.distance - inverse square law </li> <li> Slide 59 </li> <li> Slide 60 </li> <li> Slide 61 </li> <li> Slide 62 </li> <li> Nagasaki Japan August 9, 1945 </li> <li> Slide 63 </li> <li> Nuclear review 1.A radioactive atom will lose the greatest amount of mass when it emits 1. a neutron' 3.a beta particle, 2. a proton 4.an alpha particle 2A sample of iodine-131 contains 10. grams. Approximately how much iodine-131 will remain after 24 days (half life -8 days)? 1. 1.25g 3. 5.0 g 2. 2.5 g 4. 10. g 3.What is the moderator in a nuclear reactor? 1. carbon dioxide 3. cadmium 2. boron 4. graphite You have a review test </li> <li> Slide 64 </li> <li> 4.In the reaction 90 Th 234 -&gt; 91 Pa 234 + X, X represents 1.a neutron 3. an alpha particle 2.a positron 4. a beta particle 5.One of the biggest advantages of a fusion reactor is it 1. produces no radioactive wastes 2. is small in size 3. will never explode 4. has no reaction control problem 6.Which particle has the least mass? 1. alpha particle 2. proton 3. neutron 4. electron </li> <li> Slide 65 </li> <li> 7.A neutron has approximately the same mass as 1. an alpha particle 3. an electron 2. a beta particle 4. a proton 8.When 88 Ra 226...</li></ul>

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