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CHAPTER 21. NUCLEAR CHEMISTRY. NUCLEUS. NUCLEONS ARE MADE UP OF PROTONS AND NEUTRONS NUCLIDE IS AN ATOM IDENTIFIED BY THE NUMBER OF PROTONS AND NEUTRONS NUCLEAR BINDING ENERGY IS THE ENERGY RELEASED WHEN A NUCLEUS IS FORMED FROM NUCLEONS. NUCLEAR REACTIONS. CHANGES THE NUCLEUS OF A REACTION
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CHAPTER 21 NUCLEAR CHEMISTRY
NUCLEUS • NUCLEONS ARE MADE UP OF PROTONS AND NEUTRONS • NUCLIDE IS AN ATOM IDENTIFIED BY THE NUMBER OF PROTONS AND NEUTRONS • NUCLEAR BINDING ENERGY IS THE ENERGY RELEASED WHEN A NUCLEUS IS FORMED FROM NUCLEONS
NUCLEAR REACTIONS CHANGES THE NUCLEUS OF A REACTION EXAMPLE + +
RADIOACTIVE DECAY • SPONTANEOUS DISINTEGRATION OF A NUCLEUS INTO A SLIGHTLY LIGHTER NUCLEUS, ACCOMPANIED BY EMISSION OF PARTICLES, ELECTROMAGNETIC RADIATION OR BOTH
ALPHA EMISSION • AN ALPHA PARTICLE IS TWO PROTONS AND TWO NEUTRONS BOUND TOGETHER AND IS EMITTED FROM THE NUCLEUS DURING RADIOACTIVE DECAY
EXAMPLE +
BETA EMISSION • A BETA PARTICLE IS AN ELECTRON EMITTED FROM THE NUCLEUS DURING RADIOACTIVE DECAY
+ + EXAMPLE
POSITRON EMISSION • A POSITRON IS A PARTICLE THAT HAS THE SAME MASS AS AN ELECTRON, BUT HAS A POSITIVE CHARGE.
+ + EXAMPLE
ELECTRON CAPTURE • AN INNER ORBITAL ELECTRON IS CAPTURED BY THE NUCLEUS OF ITS OWN ATOM
EXAMPLE + +
GAMMA EMISSION • GAMMA RAYS ARE HIGH-ENERGY ELECTROMAGNETIC WAVES EMITTED FROM A NUCLEUS AS IT CHANGES FROM THE EXCITED STATE TO A GROUND ENERGY STATE.
PRACTICE The alpha decay of iridium-174
PRACTICE The beta decay of platinum-199
PRACTICE Positron emission from sulfur-31
PRACTICE Krypton-76 undergoes electron capture
HALF LIFE-t1/2 • TIME REQUIRED FOR HALF OF THE ATOMS OF A RADIOACTIVE NUCLIDE TO DECAY
HALF LIFE CALCULATIONS t1/2=TIME ELAPSED X 1/HALF LIFE AMT REMAINING=STARTING AMT X (1/2)n WHERE n=THE NUMBER OF HALF-LIVES
EXAMPLE PHOSPHORUS-32 HAS A HALF LIFE OF 14.3 DAYS. HOW MANY MILLIGRAMS OF PHOSPHORUS-32 REMAIN AFTER 57.2 DAYS IF YOU START WITH 4.0 mg OF THE ISOTOPE? 0.25mg
PRACTICE If the half-life for the radioactive decay of zirconium-84 is 26 minutes and I start with a 175 gram sample, how much will be left over after 104 minutes? 10.9g
PRACTICE ASSUMING A HALF-LIFE OF 1599 YEARS, HOW MANY YEARS WILL BE NEEDED FOR THE DECAY OF 15/16 OF A GIVEN AMOUNT OF RADIUM-226? 6396 YEARS