Lecture 25 - Nuclear Chemistry

Tuesday, April 23, 2024

9:00 AM

Please complete course evaluations https://boisestate.bluera.com/boisestate/ +1% if >70% respond (we are at 63%!) Please complete this questionnaire to reflect on ﷟HYPERLINK "https://boisestatecanvas.instructure.com/courses/28698/assignments/923957"Chemistry Attitudes and Experiences (End of Semester) (due April 26th) Midterm 4 is graded. Please review your exam on Gradescope and with the key outside SCNC 336 Class notes (1-24): https://bricejurban.github.io/CHEM101/ Assignments this week: ﷟HYPERLINK "https://boisestatecanvas.instructure.com/courses/28698/modules/items/3067394"HW 15 Acids and Bases due Tuesday 4/23 ﷟HYPERLINK "https://boisestatecanvas.instructure.com/courses/28698/assignments/967944"HW 16 Nuclear Chemistry due Monday 4/29 Read Chapter 9 Reminders: ﷟HYPERLINK "https://boisestatecanvas.instructure.com/courses/28698/assignments/967954"Final Exam is April 30th at 9:30 AM The final exam is cumulative and multiple choice ﷟HYPERLINK "https://boisestatecanvas.instructure.com/courses/28698/modules/items/3073947"Practice Exam (copies at back of lecture hall and under Week 16 Module) Monday 4/29 is the last day to submit any late Aktiv Chemistry assignments My CIC (EDUC 107) Hours: Friday 11AM - 1PM Office Hours (SCNC 314 or Zoom): ﷟HYPERLINK "https://calendly.com/bricejurban/office-hours"By appointment Today (4/23) What is Nuclear Chemistry? Review of the atom and isotopes Nuclear Reactions Half-Life Fission vs Fusion Thursday (4/25) Final Exam Review Tuesday (4/30) ﷟HYPERLINK "https://boisestatecanvas.instructure.com/courses/28698/assignments/967954"Final Exam at 9:30 AM https://chemteam.info/Radioactivity/Radioactivity.html has helpful tutorials on today's topic. Review of the Atom and Isotopes Untitled picture.png SUBATOMIC PARTICLES TABLE 1.1 Particle Electron Proton Neutron Mass (kg) 9.109 x 100' 1.672 X 1.675 X Mass (amu) 5.486 x 1.0073 1.0087 Charge (e) Location Outside nucleus Inside nucleus Inside nucleus Untitled picture.png Isotopic Notation (with charges) 15 3- Mass Number (A) Charge Atomic Number (Z) 7 Element Symbol The atom has internal structure. Protons and neutrons have internal structure as well. Untitled picture.png Machine generated alternative text: Structure within the atom size < 10-19m < 10-18m Nucleus Neutron size = 10-14m Proton = 10-15m _ 10-10m Many nuclei have many protons and neutrons. We need to account for all of these using isotopic notation Untitled picture.png Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings
Untitled picture.png Isotopic Notation (with charges) 15 3- Mass Number (A) Charge Atomic Number (Z) 7 Element Symbol Untitled picture.png Machine generated alternative text: Structure within the atom size < 10-19m < 10-18m Nucleus Neutron size = 10-14m Proton = 10-15m _ 10-10m Untitled picture.png Nuclear Decay Processes There are thousands (>3000) of known isotopes of the elements. Only about 300 are considered stable Stable isotopes show no evidence of radioactive decay The plot to the right shows a plot of neutron number N as a function of Atomic number Z. The stable isotopes (blue) follow a line with slope N/Z = 1 for Z < 40 & N/Z ~ 1.5 for Z >40 When an isotope is too neutron or proton heavy it will decay to change its N/Z ratio to a stable ratio There are three main classes of nuclear decay processes which can be categorized by changes in the atomic number, neutron number, mass number, and charge as well as typical energies of the emitted particle Alpha α Beta β There are three different modes of β decay β– (electron) emission β+ (positron) emission EC (electron capture) Gamma γ 180px-Alfa_beta_gamma_radiation.svg.png Alpha particles may be completely stopped by a sheet of paper, beta particles by aluminium shielding. Gamma rays can only be reduced by much more substantial mass, such as a very thick layer of lead. Untitled picture.png Machine generated alternative text: 160 150 140 130 120 110 A = 111 isobar 100 90 80 70 60 Beta emission A = 48 isobar 30 Positron emission or 20 electron capture 10 Alpha emission iiiiiii • Stable • Radioactive 10 20 30 40 50 60 70 80 90 100 110 Atomic number, Z Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings
180px-Alfa_beta_gamma_radiation.svg.png Other nuclear decay processes include IC (Internal conversion) (relaxation of excited nuclei by e– emission) proton emission (very small N/Z, protons "boil off" from the nuclei) neutron emission (very large N/Z, neutrons "boil off" from the nuclei) spontaneous fission (split into two daughter nuclei of about equal size) https://en.wikipedia.org/wiki/Radioactive_decay#List_of_decay_modes for more exotic types Untitled picture.png Machine generated alternative text: 160 150 140 130 120 110 A = 111 isobar 100 90 80 70 60 Beta emission A = 48 isobar 30 Positron emission or 20 electron capture 10 Alpha emission iiiiiii • Stable • Radioactive 10 20 30 40 50 60 70 80 90 100 110 Atomic number, Z Untitled picture.png Machine generated alternative text: Decay Type ß ß EC Emitted Particle Energetic e Energetic e ve Photon Electron Typical Energy of Emitted Particle AZ -2 o o -2 o o AA o o 0.1 0.1 < Ee < 2 MeV 60Ni* 125 SU Example Th+a 14N + + ve 22 N e + + Ve Ni+y 125Sb + e Occurrence z > 83 (N/Z) < (N/Z) light nuclei (N/Z) < (N/Z) stable heavy nuclei Any excited nucleus Cases where y-ray emission is inhibited 1024px-Radioactive_decay_modes.svg.png undefined Nuclear reactions are written and balanced much like chemical reactions, with both the mass number A and the electric charge being conserved. To remember both mass number (and charge) we represent the elementary particles by the symbols There are two other important particles. We will generally omit these but they are always present in β decay processes to conserve "lepton" number. Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings
Nuclear reactions are written and balanced much like chemical reactions, with both the mass number A and the electric charge being conserved. we represent the elementary particles by the symbols with charge without charge Proton 11p+ 11p Neutron 10n0 10n Electron 0–1e– 0–1e Positron 0+1e+ 0+1e α-particle 42He2+ 42He γ-photon 00γ0 γ There are two other important particles. We will generally omit these but they are always present in β decay processes to conserve "lepton" number. electron neutrino νe product in β+ and EC electron antineutrino ̅νe product in β– Untitled picture.png Machine generated alternative text: @ @ @ Alpha decay ...l no laughing matter! Untitled picture.png Machine generated alternative text: 2He {44 D Proton rich nuclei (Z > 83) can decay into more stable isotopes by emitting protons and neutrons in the form of an α-particle. An alpha particle contains 2 protons and 2 neutrons. Thus Z and N are both reduced by 2 and the mass number A is reduced by 4. This is depicted by the diagram at the left. A parent nuclide P decays to a daughter nuclide D and emits an α-particle Alpha decay: AZP → (A-4)(Z-2)D + 42He Examples include: Uranium-238: Radon-222: Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings
Untitled picture.png Machine generated alternative text: 2He {44 D Polonium-210: Untitled picture.png Machine generated alternative text: Betra Beta Decay ... a bit negative? Untitled picture.png Proton-deficient nuclei (high N/Z ratio) can decay by transforming a neutron into a proton, which results in the emission of a beta-minus (β–) particle (electron) and antineutrino ̅νe. We use the symbol 0–1e for the emitted electron to help us balance nuclear reactions. This is depicted by the diagram at the left. In this nuclear process, a neutron is converted into a proton. N decreases by 1, Z increases by 1, and A stays the same. Beta-minus decay: AZP → A(Z+1)D + 0–1e + ̅νe Examples include: Carbon-14: Phosphorus-32 Strontium-90 Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings
Untitled picture.png Untitled picture.png Machine generated alternative text: Betra Beta Decay ... positron a bit Untitled picture.png Machine generated alternative text: z-ID Proton-rich nuclei (low N/Z ratio) can decay by transforming a proton into a neutron, which results in the emission of a beta-plus (β+) particle (positron) and neutrino νe. We use the symbol 0+1e for the emitted positron to help us balance nuclear reactions. This is depicted by the diagram at the left. In this nuclear process, a proton is converted into a neutron. N increases by 1, Z decreases by 1, and A stays the same. Beta-plus decay: AZP → A(Z–1)D + 0+1e + νe Examples include: Carbon-11: Fluorine-18: Positron Emission Tomography (PET) is an imaging technique that has can be used to detect tumors. When a positron is emitted by a nuclear tracer it will come in contact with an electron shortly and the resulting annihilation results in the production of two high-energy gamma-rays that can be detected. The most important radioisotopes for PET are 11C, 13N, 15O, and 18F which decay after 20, 10, 2, and 110 minutes. These isotopes are produced in particle accelerators called cyclotrons and must be incorporated quickly into molecules that can be metabolized by the body. One example is (18F)fluoro-D-glucose (FDG) which is used in cancer studies. Other molecules include 15O2,15OH2, and 13NH3 used to measure blood flow in the heart and brain. Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings
Untitled picture.png Machine generated alternative text: z-ID Untitled picture.png Machine generated alternative text: e Betra For those that don't like position emission let me introduce you to . . . Electron Capture Untitled picture.png Electron capture is another process by which proton-rich nuclei (low N/Z ratio) can decay by transforming a proton into a neutron. This does not involved a positron, but as the name implies is the result of the nucleus capturing an orbital electron. This results in the conversion of a proton to a neutron (as in positron emission). The only emitted particle is a neutrino. This is depicted by the diagram at the left. In this nuclear process, a proton is converted into a neutron. N increases by 1, Z decreases by 1, and A stays the same. Electron Capture: AZP + 0–1e→ A(Z–1)D + νe Examples include: Cadium-109: Xenon-127: Lanthanum-137: Half-Life of Nuclear Decay Untitled picture.png Isotopes play a critical role in nuclear chemistry. Many isotopes have unstable nuclei that decay over time, a property utilized in fields like radiometric dating and cancer treatment. Radiocarbon dating, for instance, measures the decay of carbon-14 to determine the age of organic materials up to about 50,000 years old. Untitled picture.png Machine generated alternative text: Nuclide (tritium) 4Be Itc Il a 1%La 86Rn 2åTh BNP 2%pu 12.26 years —1 x 10 5730 years 2.601 years 15.02 hours 14.28 days 87.2 days 3.01 x 105 years 1.28 x 109 years 44.6 days 5.27 years 29 years 453 days 59.7 days 8.041 days 36.41 days —6 x 104 years 3.824 days 1600 years 1.40 x 1010 years 7.04 x 108 years 4.468 x 109 years 2.350 days 2.411 x 104 years Decay Mode e e e e e e e Je- (89.3%) IE.c. (10.7%) e e e E.C. E.C. e E.C. E.C. e Daughter 12Mg 47 Ag 54 Xe 2%Rn 2åpu Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings
Untitled picture.png Psychokinetic Energy Meter used to detect supernatural activity (Fake science) Untitled picture.png Geiger counters used to detect radioactivity use a Geiger–Müller tube to sense radiation (Real science) Isotopes play a critical role in nuclear chemistry. Many isotopes have unstable nuclei that decay over time, a property utilized in fields like radiometric dating and cancer treatment. Radiocarbon dating, for instance, measures the decay of carbon-14 to determine the age of organic materials up to about 50,000 years old. Nuclei with an unfavorable N/Z ratio have a limited lifespan. It is impossible to predict exactly when any particular atom will decay as decay is a stochastic event. However, when we measure a sample of a given nuclide it will have an average disintegration rate (A) that is consistent from one sample to another. A plot of ln A against time t is linear with slope –k = –(ln2)/t½ The time it takes for a sample to be reduced to half its initial value in a time t½ is called the half-life Untitled picture.png Machine generated alternative text: Nuclide (tritium) 4Be Itc Il a 1%La 86Rn 2åTh BNP 2%pu 12.26 years —1 x 10 5730 years 2.601 years 15.02 hours 14.28 days 87.2 days 3.01 x 105 years 1.28 x 109 years 44.6 days 5.27 years 29 years 453 days 59.7 days 8.041 days 36.41 days —6 x 104 years 3.824 days 1600 years 1.40 x 1010 years 7.04 x 108 years 4.468 x 109 years 2.350 days 2.411 x 104 years Decay Mode e e e e e e e Je- (89.3%) IE.c. (10.7%) e e e E.C. E.C. e E.C. E.C. e Daughter 12Mg 47 Ag 54 Xe 2%Rn 2åpu The decay rates of unstable nuclei range from fractions of a second to billions of years. Untitled picture.png Machine generated alternative text: 133Xe undergoes beta decay and has a half life of 5 days decay to 6_25 g? 50 How long will it take a 50.0 g sample of 133Xe to 0 5 10 15 20 25 Mass of131Xe 50 Half Lives: 30 10 10 15 Time (davs) Ink Drawings Ink Drawings
Untitled picture.png Machine generated alternative text: 133Xe undergoes beta decay and has a half life of 5 days decay to 6_25 g? 50 How long will it take a 50.0 g sample of 133Xe to 0 5 10 15 20 25 Mass of131Xe 50 Half Lives: 30 10 10 15 Time (davs) The half life for 131I, which undergoes beta decay, is 8 days. How many grams will be left if 200. g of 131I is left for 32 days? Time (days) 0 8 16 24 32 Mass (g) 200 100 50 25 12.5 Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings
80.0 g of a sample of 60Co, which undergoes beta decay, was originally placed in a container. After 20 years, 5.0 g remained. What is the half-life of 60Co? Time (years) 0 5 10 15 20 Mass (g) 80 40 20 10 5 20 years 80 g initially 5 g remaining 134Cs, which undergoes beta decay, has a half-life of 2 years. What was the original amount of a sample of 134Cs if 6 grams remained after 10 years? Time (years) 0 2 4 6 8 10 Mass (grams) 192 96 48 24 12 6 Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings
An alternate way to solve more complicated decay problems involves using this equation: (No) (1/2)total time / half-life time = N where No is the initial amount and N is the final amount How many years will it take for 88.0 grams of tritium to decay to an 11.0 gram sample? (The half-life of tritium is 12.3 years.) The decay of radioactive nuclides with known half-lives enables geochemists to measure the ages of rocks and organic material from their isotopic compositions Carbon-14 Decay Very high-energy cosmic rays produce neutrons that collide with nitrogen-14 nuclei in the atmosphere to produce carbon-14 nuclei The resulting carbon-14 enters the carbon reservoir by mixing with stable carbon-12 as H14CO3- in the ocean and as 14CO2 in the atmosphere and in tissues of plants and animals. The radioactive element carbon-14 has a half-life of 5730. years  The carbon-14 decay rate of a sample obtained from a young tree is 0.296 disintegration per second per gram of the sample. Another wood sample prepared from an object recovered at an archaeological excavation gives a decay rate of 0.109 disintegration per second per gram of the sample. What is the age of the object? Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings
Decay of Uranium 238 to Lead-206 Untitled picture.png Machine generated alternative text: 238 234 230 226 222 218 214 210 206 81 219b 219b 82 83 84 PO 84 PO 84 PO 85 86 Ru 86 87 88 89 åTh 90 91 Pa 91 92 Atomic number, Z Uranium-238 (the most common isotope of uranium) has a half-life of 4.468 × 109 years and after a series of (relatively) short-lived intermediates (see decay chain to the left) ends in the stable lead isotopes lead-206. A detailed analysis of the 206Pb to 238U ratio can determine the age of a mineral. The oldest rocks on earth are about 3.8 billion years old An estimate of the age of the earth and solar system (4.5 billion years old) comes from isotopic analysis of meteorites believed to have formed at the same time. How much U-238 should be present in a sample 2.50 x 109 years old, if 2.00 grams was present initially? Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings Ink Drawings
Untitled picture.png Machine generated alternative text: 238 234 230 226 222 218 214 210 206 81 219b 219b 82 83 84 PO 84 PO 84 PO 85 86 Ru 86 87 88 89 åTh 90 91 Pa 91 92 Atomic number, Z Nuclear Fission vs Nuclear Fusion Nuclear fission is the process of splitting a heavy nucleus into lighter nuclei, typically induced in nuclear reactors and atomic bombs, releasing large quantities of energy. Fusion, on the other hand, involves combining light nuclei, such as hydrogen isotopes, to form heavier nuclei, as occurs in the sun, also releasing immense energy. Untitled picture.png Machine generated alternative text: 142 56 235 92 92 235 92 235 92 133 51 101 41 140 54 94 38 235 92 235 92 235 92 235 92 The fission of 235U follows many different pathways, and some 34 elements have been identified among the fission products. In any single fission event two particular nuclides are produced together with two or three secondary neutrons; collectively, they carry away about 200 MeV of kinetic energy. Usually, the daughter nuclei have different atomic numbers and mass numbers so the fission process is asymmetric. Three of the many pathways are Untitled picture.png Machine generated alternative text: 72 30 zn + ä?Sr + 94 36 + 162 62Sm 2 011 153 54 xe 3 011 139 56 Ba 3 011 Ink Drawings
Untitled picture.png Machine generated alternative text: 142 56 235 92 92 235 92 235 92 133 51 101 41 140 54 94 38 235 92 235 92 235 92 235 92 Untitled picture.png Untitled picture.png Machine generated alternative text: Molten sodium or liquid water under high pressure (carries heat to steam generator) Nuclear reactor Control rod Uranium fuel Steam Steam generator Pump Heat exchanger Pump Pump 800 F Steam turbine (generates electricity) Condenser (steam from turbine is condensed by river water) River 1000 F Most nuclear power reactors in the United States use pellets of UO2 that have been sintered to form hard ceramics, which are then inserted into fuel rods. The uranium is primarily 238U, but the amount of 235U is enriched above natural abundance to a level of about 3%. The moderator used to slow the neutrons (to increase the efficiency of the fission) is ordinary water in most cases, so these reactors are called “light-water” reactors. The controlled release of energy by nuclear fission in power reactors demands a delicate balance between neutron generation and neutron loss. Control rods containing 112Cd or 10B, with large neutron capture efficiencies, effectively control the neutron flux. These rods are automatically inserted into or withdrawn from the fissioning system in response to changes in the neutron flux. As the nuclear reaction proceeds, the moderator (water) is heated and transfers its heat to a steam generator. The steam then goes to turbines that generate electricity Nuclear fusion is the union of two light nuclides to form a heavier nuclide with the release of energy. Fusion processes are often called thermonuclear reactions because they require that the colliding particles possess very high kinetic energies, corresponding to temperatures of millions of degrees, before they are initiated. Fusion is a process that occurs naturally in all stars hot enough to sustain fusion. The_Sun_in_white_light.jpg
Nuclear fusion is the union of two light nuclides to form a heavier nuclide with the release of energy. Fusion processes are often called thermonuclear reactions because they require that the colliding particles possess very high kinetic energies, corresponding to temperatures of millions of degrees, before they are initiated. Fusion is a process that occurs naturally in all stars hot enough to sustain fusion. Untitled picture.png In the early life of a star hydrogen 11H is converted into helium 42He (through intermediate hydrogen-2 and helium-3). This process loses mass, but according to the law of conservation of mass-energy, this is converted into energy (E=mc2). Thus a small amount of mass can be converted into a massive amount of energy! The process can continue to produce heavier nuclei if the star is hot enough. Three helium atoms can combine (through intermediate beryllium) to form 12C. Nucleosynthesis can continue beyond the formation of carbon to produce nitrogen, oxygen. If temperatures continue to increase (as with red giant stars) elements as heavy as iron, cobalt and nickel can form. However, elements heavier than these can only be formed (due to the strong binding energy per nucleon) when certain massive stars explode in an events termed supernovae. Chemists such as Glenn Seaborg have produced heavy elements in particle accelerators. For example, the element technetium is not found in nature but can be produced synthetically by shooting high energy hydrogen-2 at molybdenum atoms. Elements 93-118 were all produced using particle accelerators. Science to control nuclear fusion as an energy alternative to nuclear fission is an attractive area of current research. A sustained nuclear fusion reaction would solve the energy crisis on earth. However, initiating controlled fission is difficult because bringing the two nuclei together requires a temperature of about 100 million K. Magnetic confinement fusion such as the International Thermonuclear Fusion Reactor tokamak shown below are candidates for fusion reactors. The_Sun_in_white_light.jpg The reactions that occur in main sequence stars like our sun are fusion reactions that convert hydrogen into helium and produce energy. Untitled picture.png
In the early life of a star hydrogen 11H is converted into helium 42He (through intermediate hydrogen-2 and helium-3). This process loses mass, but according to the law of conservation of mass-energy, this is converted into energy (E=mc2). Thus a small amount of mass can be converted into a massive amount of energy! The process can continue to produce heavier nuclei if the star is hot enough. Three helium atoms can combine (through intermediate beryllium) to form 12C. Nucleosynthesis can continue beyond the formation of carbon to produce nitrogen, oxygen. If temperatures continue to increase (as with red giant stars) elements as heavy as iron, cobalt and nickel can form. However, elements heavier than these can only be formed (due to the strong binding energy per nucleon) when certain massive stars explode in an events termed supernovae. Chemists such as Glenn Seaborg have produced heavy elements in particle accelerators. For example, the element technetium is not found in nature but can be produced synthetically by shooting high energy hydrogen-2 at molybdenum atoms. Elements 93-118 were all produced using particle accelerators. Science to control nuclear fusion as an energy alternative to nuclear fission is an attractive area of current research. A sustained nuclear fusion reaction would solve the energy crisis on earth. However, initiating controlled fission is difficult because bringing the two nuclei together requires a temperature of about 100 million K. Magnetic confinement fusion such as the International Thermonuclear Fusion Reactor tokamak shown below are candidates for fusion reactors. Untitled picture.png Tokamek - torus-shaped vessel that is a candidate for fusion research.

 

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