CHM115 Lecture 6 Nuclear Chemistry 1 Daily Page Thursday January 25 2024 ASSIGNMENTS not all Achieve Homework HW02 due Jan 25 HW03 due Feb 01 Reading Chapter 24 LEARNING OBJECTIVES include describing how nuclear changes differ from chemical changes defining the meanings of radioactivity nucleon nuclide and isotope comparing and contrasting the modes of radioactive decay describing how each different type of radioactive decay affects the values of the mass number A and atomic number Z predicting whether beta decay positron decay or electron capture is most likely for an unstable nuclide Every element beyond Bi atomic number Z 83 is radioactive and tends to show alpha decay Always Check Brightspace for Announcements and Deadlines Need Help Go to Recitation find your TA bring your questions SI Supplemental Instruction see Brightspace info TA Office Hours posted on Brightspace Find a study group introduce yourself to your neighbor in class and in lab Tutoring list ask the Gen Chem Office genchem purdue edu Instructor Office Hours posted on Brightspace Potential Applications of Fusion Nuclear reactions are often accompanied by energy changes a million times greater than those for chemical reactions Nuclear Chemistry is All Around Us Americium Fluorine Thorium Plutonium Uranium Chemical vs Nuclear Reactions e g 100 kJ mol e g 10000000000000 kJ mol Comparison of Energies Structure of the Neutral Atom Approximately 10 14 m Proton p positive charge Neutron n0 no charge Positive nucleus Mostly empty space Negative electrons The tiny red dot is the size of the nucleus Components of the Nucleus Most of the mass of the atom is concentrated in the dense tiny nucleus The nucleus comprises the neutrons and protons collectively called nucleons A nuclide is a nucleus with a particular composition Each isotope of an element has a different nuclide Mass Number and Atomic Mass The atomic number is the smaller one the atomic mass number is the larger one Isotopes page 57 your book Periodic Table second page your book Natural elements and isotope ratio Nucleons protons neutrons How many nucleons are in a Br nucleus How many protons How many neutrons Isotopes nucleons Terminology For isotopes Types of Decay 2He2 2He or 4 Helium nucleus 4 Decay Emission Positron emission e Electron capture Gamma radiation a photon no charge no mass n Neutron 1 0n Types of Decay Types of Decay Smoke Detectors 241 95AmO2 4 2 237 93NpO2 Half life 432 years particles ionize O2 and N2 in the ionization chamber A low level electric voltage applied across the chamber is used to collect these ions causing a continuous small electric current to flow between two electrodes When smoke enters smoke particles attach to the charged ions neutralizing them This causes the electric current to fall setting off the alarm Measuring Radioactive Decay Geiger Counters Alpha Beta Gamma Measures activity disintegrations over time An inert gas tube that conducts electricity when a particle or photon of radiation temporarily makes the gas conductive by ionizing it Balancing Nuclear Reactions Balancing Nuclear Reactions Sample Problem Complete the nuclear reactions with the particle that is emitted Sample Problem Complete the nuclear reactions with the particle that is emitted Sample Problem Which change involves alpha decay a b 212 43Tc 98 84Po 208 44Ru 82Pb 98 Please balance the equations Sample Problem Which change involves alpha decay a b 212 43Tc 98 84Po 208 44Ru 82Pb 98 no Please balance the equations Balancing Equations Sample Problem reactant charges product charges reactant mass numbers product mass numbers Balancing Equations Sample Problem reactant charges product charges reactant mass numbers product mass numbers Sample Problem Bismuth 212 decays to polonium 212 Write the balanced equation Sample Problem Bismuth 212 decays to polonium 212 Write the balanced equation Sample Problem Uranium 230 undergoes alpha decay Write the balanced equation Sample Problem Uranium 230 undergoes alpha decay Write the balanced equation Sample Problem Identify the element for Sample Problem Identify the element for 24 4 A 1 12 2 Z 1 Mass number A 27 Atomic number Z 13 The atomic number Z determines the element X What number is Z What element X does Z correspond to look at the PT Predicting Types of Nuclear Decay n p too large Increase number of protons Beta decay neutron decays to proton plus a beta particle p n too large Increase neutrons or reduce protons Positron decay or electron capture Above the band of stability Alpha decay Every element beyond Bi atomic number Z 83 is radioactive and tends to show alpha decay Predicting Types of Nuclear Decay n p too large Increase number of protons Beta decay neutron decays to proton plus a beta particle p n too large Increase neutrons or reduce protons Positron decay or electron capture Above the band of stability Alpha decay Predicting Types of Nuclear Decay decay stable decay decay e capture or decay decay emission e capture This is very much like Figure 24 2 in your text Look at it Predicting Types of Nuclear Decay How would we expect Z to decay Z Predicting Types of Nuclear Decay How would we expect Z to decay Decay increases N Z Convert proton to neutron Z Predicting Types of Nuclear Decay How would we expect X to decay X Predicting Types of Nuclear Decay How would we expect X to decay a decay b e capture c emission d decay X Predicting Types of Nuclear Decay How would we expect Y to decay a decay b e capture c emission Every element beyond Bi atomic number Z 83 is radioactive and tends to show alpha decay Predicting Types of Nuclear Decay Y How would we expect Y to decay a decay b e capture c emission Every element beyond Bi Z 83 that is radioactive tends to show alpha decay Sample Problem Which nuclides are stable and why 166 60Nd 48K Argon 32 92 46Pd 16 8O Extra Slides Sample Problem Which nuclides are stable and why 166 60Nd 48K Argon 32 92 46Pd 16 8O Sample Problem Which nuclides are stable and why 166 60Nd 48K Argon 32 92 46Pd 16 8O Sample Problem Which nuclides are stable and why 166 60Nd 48K Argon 32 92 46Pd 16 8O Sample Problem Which nuclides are stable and why 166 60Nd 48K Argon 32 92 46Pd 16 8O Sample Problem Which nuclides are stable and why 166 60Nd 48K Argon 32 92 46Pd 16 8O Sample Problem Which nuclides are stable and why 166 60Nd 48K Argon 32 92 46Pd 16 8O Sample Problem Which nuclides are stable and why 166 60Nd 48K Argon 32 92 46Pd 16 8O Sample Problem Which nuclides are stable and why