Nuclear Transformations Objectives: 1. What determines the type of decay a radioisotope undergoes? 2. How much of a sample of a radioisotope remains after each 1/2 life? 3. What are two ways that transmutation can occur? Vocabulary nuclear force, band of stability, positron, half-life, transmutation, transuranium elements

Strong Nuclear Force The strong nuclear force acts to bind the subatomic particles in the nucleus overcoming the electrostatic repulsion of the positive protons. The ability of the force to hold the nucleus together depends on the proton neutron ratio. The nuclear band of stability gives a visual overview of the relationship of the increasing neutrons that are needed to stabilize the nucleus. If the proton/neutron ration lies outside this band the atom becomes radioactive. All elements over atomic # 83 are radioactive having too many protons & neutrons most emit alpha particles to attempt stabilize the nuclei

Nuclear Stability too many neutrons - beta emission (negative) high speed electron is released changing a neutron into a proton the atomic # increases by 1 while mass stays the same too may protons relative to neutrons - positron emission (positive) high speed electron with positive charge is released changing a proton into a neutron the atomic # decreases by 1 while mass stays the same

Nuclear Stability too may protons relative to neutrons - electron capture high speed electron with impacts the nucleus changing a proton into a neutron the atomic # decreases by 1 while mass stays the same Only this equation represents the transformation of a proton into a neutron

Half-life The half-life of a radioisotope is the amount of time it takes for 1/2 of a sample to undergo radioactive decay. Every different radioisotope has a different period of half- life Simplified formula: Amount of remaining parent isotope = m( 1 / 2 ) x m = mass of sample X = number of half lives The amount of H-3 remaining after 36.9 years if the initial amount was 100g & the ½ life is 12.3yrs # of ½ lives = 36.9/12.3 = 3 y = 100g(½) 3 = 100g( 1 / 8 ) = 12.5g