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Nuclear Chemistry Nuclear chemistry is the study of the changes of the __________________ of atoms. Nuclear Reactions involve changes within the nucleus where as chemical reactions involve the loss, gain or sharing of electrons. The Nucleus Contains ________________ and neutrons. They are collectively called _____________________. Radioactivity A _____________________ nucleus holds together well. An unstable nucleus will decay or break down, releasing particles and/or energy in order to become stable. An atom with an unstable nuclei is considered “_____________________”. There are several ways radioactive atoms can decay into different atoms! Transmutation Type of nuclear reaction that will change the number of ___________________ and thus will create a different ________________________. BasicTypes of Radioactive Decay Particle Type Symbol What Happens? Atomic Alpha number decreases by ____ and mass or number decreases by ____ Atomic ***Beta number increases by _____ but the mass or number stays the same Example Penetrating Power (1) LOW: Can be blocked by paper/clothing (100) MEDIUM: can penetrate the skin; need to be protected by clothing/thin metals like aluminum Gamma No change in atomic nor mass number; occurs with other types of decay (100000) HIGH: need to be protected by thick concrete or metal like lead *** A neutron becomes a ________________ and a high speed electron that is discharged from the nucleus. Writing Balanced Nuclear Equations The ______________________ and mass number must be _____________________ on both sides of the equation. Alpha Decay of thorium-230 Beta Decay of cesium -137 You Try! 1. Beta decay of zircomium-97 2. Alpha decay of americium-241 3. Alpha decay of uranium-238 4. Complete this: 239 239 Np 93 Pu + ___________ 94 Bombarding the Nucleus All the transuranium elements (elements with atomic numbers higher than Uranium) have been made by bombarding the nucleus with neutrons and other atoms in accelerators Example: Half Life Radioactive isotopes decay at a characteristic rate measured in ____________________. A half life is the time required for _____________ of the amount of radioactive atoms to decay. The time ranges from __________________ to millions of _____________________. T= elapsed time T1/2 = half life HOW TO’s 1. To calculate the number of half lives, divide the half life (T1/2) into the total time (T). T/T1/2 = # of half lives 2. Equation to calculate remaining amount left over after a certain number of half lives have passed. Amt remaining = (initial amt) (.5)n (# of half lives) __________________________________________________________________________ Examples: 1. Suppose you have 20 grams of sodium-24. Its half-life is 15 hours. How much is left over after 60 hours. 2. Uranium-238 has a half life of 4.46 x 109 years. How long will it take for 7/8th of the sample to decay? You Try! The half life of radium-222 is 38 s. How many grams of a 12.0 g sample are left after 114 s? Nuclear Fusion Smaller atoms are _______________________ to form a large atom. Occurs in the _____________and _____________ Generates huge amounts of ____________________ Nuclear Fission Large atoms _______________ into smaller atoms Generates huge amounts of ___________________. Carried out in ___________________ Could result in a chain reaction of fission like the _____________________ Tutorials: NuclearReactions:http://ithacasciencezone.com/chemzone/lessons/11nuclear/dcayquiz.htm Half Life & Nuclear Reactions: http://www.glencoe.com/qe/science.php?qi=2696\