NUCLEAR CHEMISTRY Types of Radioactivity (TABLE O). Alpha particle:  4 He 2 = Helium nuclei Low penetrating power Low Energy (E) Beta Particle:  - positron:  + 0 Gamma Ray:  0 High energy (x-rays) High power High penetration FAST e 0 Same as a -1 charge e 0 +1 Same as a +1 charge with no mass Medium E medium penetrater 4 He 2 Atomic number # protons Mass number 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 How do we separate out and identify the types of radioactivity---use a electric or magnetic field Radioactive Source (particle) -- ,  +  Radioactivity results from an unstable ratio Between mass# and protons in the nucleus

NUCLEAR CHEMISTRY CNT’D Particle Accelerators: 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 TYPES OF PARTICLE DECAY(natural radioactivity) Alpha Emits an alpha (  ) particle Fr He 4 2 At Au e 0 +1 Hg Ca K Fr n 1 0 Fr Fr  0 0 Fr Mass number(left) = mass number (right) 220 = Atomic # (left) = atomic # (right) 87 = Emits a beta (  - ) particle Beta Positron Emits a positron (  + ) particle e 0 Neutron Emits a neutron (n) particle (note: atomic # didn’t change) Gamma Emits a gamma (  ) particle (this does not stabilize nucleus)

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

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 = mc 2 Any mass “lost” is converted to Energy Nuclear Disintegration ARTIFICIALLY MADE!! Li 6 3 n 1 0 He H 3 1 Always small masses Always a change in ID of element: Atomic # wise… 3+0 = Li changed to He Masses add up too. 6+1=3+4 FISSION Big atom(heavy)hit by a particle Breaks the nucleus of big atom up into smaller atoms (2 or more) and more particles Usually see the following: U n n U n Pu 239 CHAIN REACTION!! n U Kr Ba n 1 0 These guys can Go on and hit more Uranium FUSION COMBINES (fuses) nuclei Smaller nuclei combine to make bigger atoms H 1 1 He H H ALL produce Large amounts of ENERGY NEED HIGH TEMP/HIGH Pres. H H 3 1 He n 1 0 +ENERGY SUN DOES FUSION

USES AND PROBLEMS WITH RADIOACTIVITY RADIOACTIVE WASTE 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) N 2 (g) TRACERS: Used to trace metabolic functions and mechanisms in organic processes Common ones: 3 H, 32 P, 14 C Used to detect cracks in airplanes 60 Co 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 RADIOACTIVE DATING Geological USE Uses ½ life to calculate age Use to determine age of object, fossil, rock, preserved skeletal remains, etc. Inorganic (rock) U-235 Organic dating C-14