1.Will not take any after next Tuesday 1/13

1.Define each of these terms: You may use your notes and they do not need to be in complete sentences  Energy  Half-life  Law of Conservation of Matter  Fusion  Fission 2.Which is represented below alpha, beta, or gamma decay? 238 U 238 Nb + 0 e 9299

1.GRAPH HOW WELL YOU DID ON YOUR ENTRY TASK AND WORKSHEET AFTER YESTERDAYS DISCUSSION

Electromagnetic Spectrum

Which is more penetrating? Why? Higher Energy and Frequency

 Alpha decay occurs only in heavier elements of atomic number 52, tellurium, and greater.  Beta & Gamma were seen in all of the elements.  Radioactive decay is seen in all isotopes of all elements of atomic number 83.(Wikipedia)  Nuclei with atomic number > 83 are radioactive

Nuclear Stability Half-Life

A nucleus decays because it is unstable. The daughter nucleus is more stable than the parent So you will not have the same element after the parent material decays Decrease of Protons & Neutrons by 2

Alpha Decay Uranium Thorium Alpha Particle

What are the products of Carbon going through alpha decay Lets write it out

Occurs in a nucleus w/ too many protons or too many neutrons When decays also gives off an e - (no mass, neg. charge) called a beta particle The resulting reaction is the same mass, but an increase of one proton How?

Neutrons are composed of 1 e - & 1 proton Neutron decays to release 1 e - what do you have left? One Proton

Beta Decay Thorium Protactinium Beta Particle

What are the products of Carbon going through beta decay Lets write it out

a nucleus changes from a higher E state to a lower E thru the release of EM radiation (photons). The # of protons (and neutrons) in the nucleus doesn’t change, so parent and daughter are same element

Half-Life

Common Radioactive Isotopes Isotope Half-Life Radiation Emitted Carbon-14 5,730 years β, γ Radon daysα Uranium x 108 years α, γ Uranium x 109 years α

Radioactive Half-Life After one half life there is 1/2 of original sample left. After two half-lives, there will be 1/2 of the 1/2 = 1/4 the original sample.

Example You have 100 g of radioactive C-14. The half-life of C-14 is 5730 years. How many grams are left after one half- life? How many grams are left after two half- lives? Answer: 50 g Answer: 25 g