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LESSON 2: Nuclear Chemistry, Radioactivity and Radioactive DecayMost elements are stable, but some elements are unstable and break apart into smaller atoms. Scientists discovered thatwhen elements spontaneously decay, they give off alpha particles (helium nuclei) and beta particles (electrons), orgamma rays (high energy radiation).To “balance” a nuclear reaction, one must still take the Law of Conservation of Mass into account.Briefly stated, thetotal MASS number. Chemical reactions are like “sentences” in chem-speak.To have a proper chemical reaction, wemust make sure there are equal numbers of atoms on BOTH sides of a reaction—otherwise we violate the Law ofConservation of Mass!Recall that for a given isotope, the correct symbol is:Where A is the MASS number (= # protons + # of Neutrons)Where Z is the ATOMIC number (= # of Protons)Just like a chemical reaction, in a nuclear reaction, both the mass number and atomic number must balance on bothsides of the reaction.Ex: Write the balanced nuclear reaction for the alpha decay of Thorium-235.Assume only an alpha particle andanother single decay product forms.Answer:1.Write down the correct symbol (including mass and atomic number) for the reactants and (known) products.