“More illness is caused by improper water than any other reason and largely because radioactivity is lost from our daily supply of drinking water. "By the patented composition of highly selected and scientifically compounded radium ores of which the Revigator is made, this lost element is perpetually restored to all drinking water placed therein."

Nuclear Chemistry Radioactive decay: Unstable isotopes (radioisotopes) have either too many or too few neutrons They become stable by releasing energy in the form of radiation particles Radioisotope: An unstable isotope of an element Discovery: 1896, by Becquerel. He studied the phenomenon with his partners Pierre and Marie Curie Marie coined the term “radioactivity”

Radioactive decay: Penetrating power: The ability of a radiation particle to penetrate through matter Ionization ability: The ability of a radiation particle to knock an electron off of an atom it strikes (ionization)

4 +2 -1 +1 Alpha particle Beta particle Positron Gamma ray TYPE OF PARTICLE SYMBOL MASS CHARGE PENETRATING POWER IONIZING ABILITY Alpha particle Beta particle Positron Gamma ray Stopped by paper  or 4 +2 High - or -1 Moderate Moderate + or +1 Very high Very low

particle: Composed of two protons and two neutrons Identical to a helium nucleus A high-energy electron A high-energy photon (particle of light) Similar to x-rays

Natural transmutation: A change in a nucleus’ number of protons due to radioactive decay One element can change into another one

Factors Affecting Rate Subatomic Particles Involved Comparison of Chemical And Nuclear Reactions (In Nature) CHEMICAL NUCLEAR Energy Transfer Factors Affecting Rate Spontaneous? Subatomic Particles Involved Can be endo- or exothermic Always exothermic Temperature, nature of reactants, concentration, etc Rate cannot be changed Requires activation energy Always spontaneous Nucleons (protons and neutrons) Valence electrons

Artificial transmutation: A nucleus of one element is bombarded by high energy particles, changing it into a different element Particle accelerator: Uses electric and magnetic fields to accelerate charged particles close to the speed of light and then smash them into another nucleus Transuranium elements: All elements past 92 Created artificially via particle acceleration. Do not exist in nature

Solving half-life problems: The amount of time it takes for half of the nuclei of a given radioisotope to undergo decay Different for each radioisotope (See Table N) Cannot be changed by any means # of half lives: 1 2 3 4 5 6 7 8 100% Amount Remaining: Solving half-life problems: To calculate the number of half-lives that have gone by: number of half-lives = Total time Half-life

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Radioactive dating: Since radioisotopes decay at a known rate, we can use the remaining amount to determine a sample’s approximate age

Nuclear fission and fusion: Mass defect: The difference between the mass of an atom and the mass of the sum of its protons and neutrons The missing mass is converted into energy according to E=mc2

Nuclear fission: For large atoms, the mass of the whole atom is greater than the sum of its protons and neutrons A neutron strikes a nucleus (usually U-235 or Pu-239), splitting it into two smaller nuclei, accompanied by the release of several neutrons and a lot of energy Ex: Chain reaction: An atom undergoes fission and releases several neutrons. These neutrons strike other atoms, causing them to undergo fission. Requires a critical mass of fissionable material

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Uncontrolled fission: Controlled vs. Uncontrolled Fission Uncontrolled fission: A nuclear bomb The entire chain reaction is completed in a fraction of a second releasing enormous energy Uranium-235 Fission Bomb Plutonium-239 Fission Bomb Controlled fission: Nuclear reactor Excess neutrons are absorbed by control rods, slowing the chain reaction Heat from the reaction is used to generate electricity Fuel rods: Either U-235 or Pu-239. A critical mass of fissionable material is required

Nuclear fusion: Two nuclei are joined to become one Releases 1000 times the energy of fission Requires conditions of enormous temperature and pressure Ex: Uncontrolled fusion: a hydrogen (thermonuclear) bomb: Uses a fission bomb to generate the high temperature and pressure needed for fusion to occur Click For Animation Click For Animation

Controlled fusion: currently under research. Not currently feasible COMPARISON OF POWER GENERATION USING NUCLEAR FISSION versus NUCLEAR FUSION NUCLEAR FISSION NUCLEAR FUSION Advantages Disadvantages Relatively cheap, no burning of fossil fuels, no greenhouse gases Fuel is cheap and plentiful, no radioactive waste, more energy than fission Waste products stay radioactive for thousands of years, danger of meltdown or radiation release Technology has not yet been perfected

Uses of radioisotopes: Medical and scientific: Radioactive tracer: A substance where a stable atom has been replaced by a radioactive atom Used to learn about chemical pathways in biological systems *NOTE: X-rays are not nuclear in origin Ex: Iodine-131: Used to image the thyroid gland Cancer treatment: Radiation kills rapidly dividing cancer cells

Food preservation: Radioactive dating: Kills bacteria, fungi, and insects without changing the nature of the food Uses gamma emitters like Co-60 for maximum penetration Radioactive dating: Uses known half-lives of radioisotopes to estimate the age of various substances Half life must be within the same range as the age of the object to be dated Ex: Carbon-14 used to date fossils and other organic matter

Biological hazards of radiation: Somatic (body) cells: Cell death  tissue damage Cell malfunction  cancer Reproductive cells: Cell death  sterility Cell malfunction  genetic defects passed on to future generations