NUCLEAR CHEMISTRY e e  Types of Radioactivity (TABLE O). Radioactivity results from an unstable ratio Between mass# and protons in the nucleus NUCLEAR CHEMISTRY Types of Radioactivity (TABLE O). Alpha particle:  Beta Particle: - Gamma Ray:  positron: + 4 He 2 = Helium nuclei High energy (x-rays) High power High penetration FAST e -1 e +1 Same as a -1 charge Same as a +1 charge with no mass Low penetrating power Low Energy (E) Medium E medium penetrater Mass number 4 He 2 NATURAL RADIOACTIVITY: occurs in nature (DECAY) happens spontaneously 1 thing breaks into more than one thing 1  2 All types listed on TABLE N and O Atomic number # protons How do we separate out and identify the types of radioactivity---use a electric or magnetic field +++++++++++ - Radioactive Source (particle)  , + - - - - - - - - - - -

 Fr He At Au Hg e Ca e K Fr n Fr Fr Fr Emits a beta (-) particle NUCLEAR CHEMISTRY CNT’D TYPES OF PARTICLE DECAY(natural radioactivity) Emits an alpha () particle Particle Accelerators: Alpha Fr 220 87 He 4 2 At 216 85 Can be linear or circular Work by alternating magnetic fields to accelerate the particle Particle MUST have a CHARGE or it will not be accelerated Neutron and Gamma particle DON’T WORK + Mass number(left) = mass number (right) 220 =4 + 216 Atomic # (left) = atomic # (right) 87 = 2 + 85 Emits a beta (-) particle Beta Au 198 79 Hg 198 80 + e -1 Emits a positron (+) particle Positron Ca 37 20 e +1 K 37 19 + Emits a neutron (n) particle Neutron Fr 220 87 n 1 Fr 219 87 + (note: atomic # didn’t change) Emits a gamma () particle Gamma (this does not stabilize nucleus) Fr 220 87  Fr 220 87 +

Half life: 10 kg bunny Amount of time for half of the radioactive sample to turn into (decay) something stable 3 days 5 kg bunny Decay rate Listed on table N Nothing affects ½ life!!! 3 more days 3 more days 3 more days 2.5 kg bunny remains 0.625 kg bunny remains 1.25 kg bunny remains How much time did it take for ½ the bunny to decay? How many ½ lives do we see here?

Li n H He H H He He He U n H He U n n Pu U n Ba Kr H H He n n ARTIFICIAL TRANSMUTATIONS: Man Made Particle is accelerated and shot into the nucleus of another particle (man does this) NOT SPONTANEOUS Two particles on left side of arrow yield 2 or more new particles on right side of arrow E = mc2 Any mass “lost” is converted to Energy Nuclear Disintegration FISSION FUSION ARTIFICIALLY MADE!! Big atom(heavy)hit by a particle COMBINES (fuses) nuclei Smaller nuclei combine to make bigger atoms Breaks the nucleus of big atom up into smaller atoms (2 or more) and more particles Li 6 3 n 1 H 3 1 He 4 2 + + H 1 H 1 He 2 + Usually see the following: He 4 2 Always small masses Always a change in ID of element: He 4 2 + U 238 92 n 1 + H 1 He 4 2 U 235 92 n 1 + + Atomic # wise… 3+0 = 1 + 2 Li changed to He ALL produce Large amounts of ENERGY n 1 + Pu 239 CHAIN REACTION!! NEED HIGH TEMP/HIGH Pres. U 235 92 n 1 Ba 139 56 Kr 95 36 H 2 1 H 3 1 He 4 2 n 1 Masses add up too. 6+1=3+4 + + + + n 1 +ENERGY These guys can Go on and hit more Uranium + 3 SUN DOES FUSION

USES AND PROBLEMS WITH RADIOACTIVITY RADIOACTIVE WASTE Medicine; Used to diagnose and treat cancers Need SHORT ½ life and cleared fast from the body Most common: I-131: for thyroid Tc-99: detect brain cancer Co-60: cancer treatment Radium: cancer treatment Disposed carefully –transported securely Often buried (extensively long ½ life means buried for remainder of our lives and those to come) Has to be secure Only becomes stable when it becomes a gas Rn(g) N2(g) RADIOACTIVE DATING TRACERS: Geological USE Used to trace metabolic functions and mechanisms in organic processes Uses ½ life to calculate age Use to determine age of object, fossil, rock, preserved skeletal remains, etc. Common ones: 3H, 32P, 14C Used to detect cracks in airplanes 60Co Inorganic (rock) U-235 Organic dating C-14