early pioneers in radioactivity roentgen: discoverer of x-rays 1895 becquerel: discoverer of...

Download Early Pioneers in Radioactivity Roentgen: Discoverer of X-rays 1895 Becquerel: Discoverer of Radioactivity 1896 The Curies: Discoverers of Radium and Polonium

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  • Early Pioneers in RadioactivityRoentgen:Discoverer of X-rays 1895Becquerel:Discoverer of Radioactivity 1896The Curies:Discoverers of Radium and Polonium 1900-1908Rutherford:Discoverer Alpha and Beta rays 1897

  • Radioactive BandsThe Firm- Radioactive circa 1985

    Imagine Dragons- Radioactive circa 2012

  • What do we mean by Radioactivity?Radioactive decay is the process in which an unstable atomic nucleus loses energy by emitting radiation in the form of particles or electromagnetic waves.

    There are numerous types of radioactive decay. The general idea:

    An unstable nucleus releases energy to become more stableDecay continues until a stable, non-radioactive product is formed

  • Reason for Radioactivity The number of Neutrons in the nucleus affects the stability of the atomIn some cases all the isotopes are unstable

  • Isotopes.a review-mass of the atom depends on the number of protons and neutrons in the element-isotopes are forms of the same element have different #s of neutrons but same # of protons (atomic number)ex. 12C, 13C, 14C 6 6 6-many isotopes have unstable nuclei and they release radiation (are radioactive)

  • What are the Sources of Radioactivity?Naturally Occurring Sources:Radon from the decay of Uranium and ThoriumPotassium -40 found in minerals and in plantsCarbon 14 Found in Plants and Animal tissueManmade Sources:Medical use of Radioactive IsotopesCertain Consumer products (eg Smoke detectors)Fallout from nuclear testingEmissions from Nuclear Power plants

  • Products of Radioactive DecayWhen the unstable element (Parent Isotope) decays it makes: a new element (Daughter Element) Gives off radiation 23892U 42He + 23490Th ParentradiationDaughter

  • Three Common Types of Radioactive EmissionsAlphaBetaGamma

  • Half-life- time it takes for half of the atoms in a radioactive isotope to decay Each isotope has its own HLHL cannot be altered by temperature or pressureDecay continues until a stable, non-radioactive product is formed Decay of an individual atom is random

  • Half life exponential decay

  • Carbon DatingWhen a plant dies, it stops the intake of carbonSince the 14C decays, after 5730 years, half of it will be goneWe can just weigh a piece of dead wood, calculate how much 14C it originally had and measure to how much it has now to get the age

  • Uranium DatingWe know the half -life of 238U and 235UThey have series that end in 206Pb and 207PbCompare how much U vs. special lead and calculate the age of the rock!!Carbon dating only good for about 50,000 yearsUranium rock dating good for millions of years

  • Telling time by absolute ageCarbon-14 to Nitrogen 14 in ~5700 years found in any living thingUranium-235 to lead 207 in 700 million years Potassium-40 to Argon-40 in 1.3 billion years found in the mineral feldsparUranium-238 to lead 206 in 4.5 billion years Thorium 232 to Lead 208 in 14 billion years.Rubidium 87 Strontium 87 in 48.6 billion years

  • TransmutationsThe changing of one element to another is called transmutationThis occurs whenever there is an alpha decay or a beta decay

  • Two Main Types of Nuclear ReactionsFusion - two light nuclei are combined to form a heavier, more stable nucleusThis occurs in stars to produce energy (electromagnetic radiation)Fission - a heavy nucleus is split into two nuclei with smaller mass numbersThis occurs in nuclear power plants

  • Nuclear Power PlantFission of Uranium in the reactor creates large amounts of energy to heat water, spin a turbine and generate electricity



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