DOR: Periodic Trends Circle the element with the LOWEST ionization energy 1) Potassium, Calciucm 2) Nitrogen, Fluorine Circle the element with the SMALLEST atomic radii 3) Li, Cs 4) K, Br

Nuclear Chemistry

Radioactive Decay Spontaneous breakdown of an atom’s nucleus Breakdown results in a lighter nucleus Emits electromagnetic radiation Nuclear radiation—radiation emitted from nucleus Radioactive nuclide– nucleus that goes through radioactive decay, unstable. (Ex. Uranium)

What is a nuclide Radioactive nuclide– nucleus that goes through radioactive decay unstable Contains a certain amount of energy Ex. Uranium

Types of Radioactive Decay 1) Alpha particle ( α ) Consists of 2 protons, 2 neutrons emitted during decay SO atomic # decreases by 2 and atomic mass decreases by 4 Helium nucleus ( 2 4 He )—how particle represented Can be stopped by paper, low penetrating power Equation: Po  Pb He

Types of Radioactive Decay (cont.) 2) Beta particle ( β ) Releases beta particles (electron given off during radioactive decay) Negative charge causes deflection Can be stopped by lead or glass Increase in atomic # by 1, NO change in atomic mass Neutron converts to proton and electron Gaining proton, no lose in mass because neutron converted to proton— same mass Equation: 6 14 C  7 14 N β

Types of Radioactive Decay (cont.) 3) Gamma Rays Has the most energy, only stopped by lead, high penetrating power Releases gamma rays ( γ ) from nucleus Type of electromagnetic radiation Composed of photons, released as excited nuclei fall to lower energy level Ex. X-Rays

Types of Radioactive Decay (cont.) 4) Positron Emission Release of positrons positrons — Similar to electrons, have a positive charge Creates two gamma rays—when contact with electron Proton converted to neutron and positron Atomic # decreases by 1 due to losing proton, no mass # change Ex Al  Mg e

Example 1: Nuclear equation when an alpha particle emitted by Po

Example 2:Nuclear equation when a beta particle emitted by Pb

Practice: Alpha Decay 1) Be-9 2) U-238 3) Eu-154 Beta Decay 1) Th-234 2) K-43

Half-Life Time period required for half of a radioactive nuclide to decay. Vary depending on the nuclide, unique for each nuclide. Radioactive decay series— chain of radioactive decays Begins with radioactive nuclei and ends with nonradioactive nuclei Ex. U-238 Ex C has a half-life of Therefore, if we have 10g of 14 6 C, in 5715 years we will have 5g. Some sources say 5730 years (course textbook)

Half-Life (cont.) Random decay process Radioactive decay law— Rate of radioactive decay proportional to # of atoms present in sample

Half-Life Equation A E = A O * 0.5 t/t(1/2) A E = Substance amount A 0 = Initial substance amount t = time elapsed t 1/2 = half-life

Example 1: Plutonium-239 has a half life of 24,110 years. We have 100g of this substance. How many grams will we have after 96,440 years?

Nuclear Chemistry Practice Worksheet

1) Lawrencium has a half-life of 10 hours. We have a 5 gram sample of this element. How much of this sample did we have 25 hours ago. 2) Actinium has a half-life of approximately 22 years. We now have a sample of 35 grams. How much of this sample will we have in 60 years? 3) Write the alpha equation for Th 4) Write the beta equation for Bi

AP CHEMISTRY EXAM FORMAT

Curriculum Focused on 6 “Big Ideas” that are broken down into “Enduring Understanding” and “Essential Knowledge” standards for the course. Big Ideas: Big Idea 1: Study of Matter Big Idea 2: Chemical Bonding Big Idea 3: Chemical Reactions Big Idea 4: Kinetics Big Idea 5: Thermodynamics Big Idea 6: Chemical Equilibrium

Big Ideas Broken Down Kinetics Gas Equilibrium Acid/Base Equilibrium Electrochemistry Thermochemistry Ksp and limited solubility

AP Exam 2 sections: One multiple choice– 90 minutes One free-response— 90 minutes Focus on data interpretation, modeling, conceptual explanations, experimental procedure. 50% of score on Multiple Choice, 50% on Free- Response

AP Exam (cont.) Section I—Multiple Choice Section 60 questions Analysis of data sets No calculator permitted Lots of visuals, graphs, and data Section II—Free-Response Section Calculators permitted Short and long responses (approx. 3-4 questions each) Focus: experimental design, data analysis, molecular diagrams—explanation of these concepts Spend approximately 20 minutes on each question

Tips for the AP Exam Be concise in your answer! Write in ink Box in your final answer ! Keep it organized Budget your time 1 st 15/last 15—easiest, more thought questions tend to be in the middle You do NOT have that much time to calculate an answer Label everything (answer, work, etc,) Do NOT restate the question—ANSWER it! No penalty for guessing, answer ALL questions ALWAYS provide some set-up procedure and give correct units for your answer DO NOT JUST PUT ANSWER DOWN

Labs Pay Attention to the lab procedures we utilize—what equipment is used, how to perform an experiment for a particular chemical concept Calorimetry---heat of reaction Titration—Acid/Base Determination of Chemical Formula—Empirical Formula Mass spectrometry—isotope mass Liquid chromatography—mixture separation

DOR: Nuclear Chemistry Write the following nuclear equations. 1) Alpha decay of Ir—174 2) Beta decay of platinum—199

More on Nuclear Chemistry

Nuclear Fission Nuclear reaction where nuclei are SPLIT Nucleus is broken down into a more stable nucleus heavy nucleus is broken into lighter fragments HUGE amount of energy is released Critical mass = minimum number of nuclei that can provide enough neutrons to maintain chain reaction, results in nuclear explosion. Nuclear reactors = controlled fission reactions. **Can induce a nuclear chain reaction!!!

Fission (cont.) Thermal neutrons bombard U-235 Mass is converted to energy 8 x 10 7 kJ/g More energy than burning coal Energy can be utilized ! First reaction causes the splitting of 2 more U-235 nuclei—generates a chain reaction

Nuclear Reactors Location where controlled fission reactions occur Fuel rods in the core contain enriched uranium Steam generation steam turbine electric generator Control rods take in neutrons so fission is controlled Production of radioactive waste A TON of water is used to cool the reactors

Nuclear Fusion Nuclei having a light mass are joined. Combination of light nuclei Creates heavy nucleus Results in larger, stable nucleus. MORE energy released than in nuclear fission !!! Hard to control Initiated by fission reaction (fission bomb) ---- H bomb **Type of reaction happening in the sun and stars. -fuel: hydrogen atom

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Applications Diagnostic 1) Radioisotopes Actual substance or modified into biological substance for organ targets Ex. Technetium 2) Ionizing radiation Both cancer causing and cancer treatment Use of gamma rays to target tissue Ex. Co-60 Ingestion of Radioactive Chemical Migrates to target tissue Ex. Iodine for thyroid

Applications (cont.) Radiation processing Used with medical supplies and food Treated with ionized radiation Kills microorganisms Radioactive Tracers Attach or “tag” to other substances Enables monitoring substance process or substance detection

Homework Read lab procedure on liquid chromatography Read pp ,

DOR: Liquid Chromatography 1) The ___________ phase is when the mixture is added to the chromatography column and attaches to the substrate. 2) The __________ phase occurs when a solvent is passed through the chromatography column to transport mixture components out of the chromatography column. 3) Name the type of chromatography column we will be using in lab. 4) How should you add the 10 ml of 18% isopropanol solution to the chromatography column? 5) How many trials are you doing?