 Nuclear reactions deal with the nucleus  Chemical reactions deal with electrons  What is the difference!?!?! ◦ Nuclear reactions involve unstable nuclei becoming more stable by emitting energy ◦ Unaffected by temperature, pressure or a catalyst

 The larger the element (bigger nucleus) the more likely it is radioactive (unstable) ◦ Elements > 83 = radioactive  Radioactive  root is the same as radiation ◦ They give off radiation

 More stable nuclei have ◦ Low atomic #’s ◦ Ratio of protons:neutrons = to 1:1 ◦ Even numbers of protons and neutrons

 Alpha ◦ Looks like helium without electrons 2p:2n ◦ Low penetrating power ◦ Largest particle ◦ Lowest energy  Could penetrate paper  Beta ◦ Looks like and e- but it comes from the nucleus ◦ Moderate penetrating power  could penetrate your skin α β

 Gamma ◦ Most harmful ◦ High penetrating power ◦ Very high energy, high frequency ◦ Used in nuclear medicine to kill tumors ◦ More powerful than x – rays  Can burn skin γ

 Change in # of protons, creating a new element ◦ One substance becomes another substance ParticleMass #Change Atomic # Change Alpha-4-2 Beta0+1 Gamma00

Capture Bombarded Being brought in “Reactant Side” Emit Decay Losing it “Product Side”

 An alpha particle is captured  A beta particle is emitted ◦ Beta decay OR beta emission

 Can predict if one is left out  Tops and bottoms on both side of arrow should add up Alpha Particle Emission Beta Emission (Beta Decay)

 The time it takes for half of the nuclei (substance) to decay.  Over time, substances decay ◦ Some substances have extremely long half lives (thousands of years) ◦ Some substances have very short half lives (less than seconds)

 Carbon-14 emits beta radiation and decays with a half life of 5730 years. If you start with 2.00x grams of C-14, how many grams remain after 3 half lives? 1.0g 0.5g 0.25g 1st half life 2nd half life 3rd half life 0.25x g of C-14

 So, if one half life is 5730 years, how long would 3 half lives be? 17,190 yrs

 Phosphorous-32 has a half life of 14.3 days. How many milligrams of phosphorous-32 remains after 57.2 days if you start with 4.0mg of the isotope? ◦ Question to ask: 57.2 days is how many half lives?

4 half lives 2.0mg 1.0mg 0.5mg 0.25mg after 4 half lives

 A mg sample of hydrogen-3 was collected/ After 24.52years, 0.114mg of the sample remains. What is the half-life of hydrogen-3? 1- half life 2- half lives yrs

 The breaking apart of a nucleus  Each neutron can cause its own fission reaction which can result in a chain reaction. ◦ Chernobyl ◦ Fukishima

 Mass is NOT conserved in a nuclear reaction ◦ Mass-energy is conserved  Converts “lost” mass into energy

 The combining of atomic nuclei  The sun is powered by fusion reactions