21.6: Energy 21.6: Energy Changes in Nuclear Changes in Nuclear

ReactionsReactionsCourtney Wong & Lauren Courtney Wong & Lauren

HebelHebel

Energy Associated with Nuclear Energy Associated with Nuclear ReactionsReactions

► Energy and mass of nuclear Energy and mass of nuclear reactions are related in reactions are related in Einstein's famous equationEinstein's famous equation E=mcE=mc22

►E=energyE=energy►M=massM=mass►C= speed of light (3.00 x 10C= speed of light (3.00 x 1088))

► Equation states that mass and Equation states that mass and energy are proportionalenergy are proportional If a system loses mass, it If a system loses mass, it

loses energyloses energy Vice -versaVice -versa

Mass change, Mass change, ∆m∆m►Mass changes and associated energy Mass changes and associated energy

changes are much greater in nuclear changes are much greater in nuclear reactions when compared to chemical reactions when compared to chemical reactionsreactions

►∆∆m=(total mass of products) – (total m=(total mass of products) – (total mass mass of reactants)of reactants)

►-∆m= exothermic = spontaneous nuclear -∆m= exothermic = spontaneous nuclear reactionreaction

Example Example ∆m Problem∆m Problem►226226

8888Ra --> Ra --> 2222228686Rn + Rn + 44

22HeHe►(mass of p) - (mass of r)(mass of p) - (mass of r)►∆∆m = m = Mass of one mole of Mass of one mole of 44

22He + mass He + mass of one mole of of one mole of 222222

8686Rn – mass of one Rn – mass of one mole of mole of 226226

8888RaRa►Δm = 4.0015 g + 221.9703 g - 225.9771 Δm = 4.0015 g + 221.9703 g - 225.9771

gg►Δm = -0.0053 gΔm = -0.0053 g

Reaction:

Using ∆m In Einstein’s Using ∆m In Einstein’s EquationEquation

►Rearranged as Rearranged as ∆E=c∆E=c22∆m∆m►To obtain ∆E in joules, ∆m must be To obtain ∆E in joules, ∆m must be

converted to Kg when used in the equationconverted to Kg when used in the equation►Example: ContinuedExample: Continued►∆∆m = m = -0.0053 g-0.0053 g►∆∆E = (2.9979 x 10E = (2.9979 x 1088))22 (-0.0053) (-0.0053)

(1kg/1000g)(1kg/1000g) ∆∆E=-4.8x10E=-4.8x101111

Nuclear Binding EnergiesNuclear Binding Energies►1930’s: scientists discovered that mass of 1930’s: scientists discovered that mass of

individual parts of the nucleus always individual parts of the nucleus always weighs more that the nucleus itselfweighs more that the nucleus itself

►Ex:Ex: Helium-4 nucleus has a mass of 4.00150 amuHelium-4 nucleus has a mass of 4.00150 amu

Mass of two protons = 2(1.00728 amu) = 2.01456 amu Mass of two protons = 2(1.00728 amu) = 2.01456 amu Mass of two neutrons= 2(1.00728 amu) = 2.01456 amu Mass of two neutrons= 2(1.00728 amu) = 2.01456 amu Total Mass = Total Mass = 4.03188 amu4.03188 amu

►Ex: (continued)Ex: (continued)Mass of two protons and two neutrons = 4.03188 amuMass of two protons and two neutrons = 4.03188 amu Mass of Mass of 44

22He nucleus = 4.00150 amuHe nucleus = 4.00150 amuMass Difference (∆m) = Mass Difference (∆m) = 0.03038 amu0.03038 amu

Mass DefectMass Defect: the mass difference between a nucleus : the mass difference between a nucleus and it individual nucleonsand it individual nucleonsIncrease in mass = increase in energyIncrease in mass = increase in energy Energy + Energy + 44

22He 2He 21111p + 2p + 211

00n son so∆∆E=cE=c22∆m∆m = = (2.9979 x 10(2.9979 x 1088 m/s) m/s)22 (0.03038 amu) ( (0.03038 amu) ( ) ( ) ( ))

= = 4.534 x 104.534 x 10-12-12 J J 1g

6.022 x 1023 amu

1kg 1000g

Nuclear Binding Energy

Nuclear Binding EnergyNuclear Binding Energy►The energy required to break apart a The energy required to break apart a

nucleus into its individual nucleonsnucleus into its individual nucleons The larger the binding energy the more The larger the binding energy the more

stable the nucleus is towards decompositionstable the nucleus is towards decompositionNucleus

Mass of Nucleus (amu)

Mass of Individual Nucleons (amu)

Mass Defect (amu)

Binding Energy (J)

Binding energy per Nucleon (J)

42H

e4.00150 4.03188 0.0303

84.53 x 10-12

1.13 x 10-12

5626Fe 55.9206

856.44914

0.52846

7.90 x 10-11

1.41 x 10-12

23892U 238.0003

1239.93451

1.93420

2.89 x 10-10

1.21 x 10-12

Nuclear Binding EnergyNuclear Binding Energy►Binding energy per nucleon increases Binding energy per nucleon increases

in magnitude as mass number in magnitude as mass number increases, reaching ~1.4 x 10increases, reaching ~1.4 x 10-12-12 J J (mass number of nuclei close to iron-(mass number of nuclei close to iron-56)56)

►Then it decreases to ~1.2 x 10Then it decreases to ~1.2 x 10-12-12 J for a J for a very heavy nucleivery heavy nuclei

42He

5626F

e 23892U

►Trend: nuclei of intermediate mass Trend: nuclei of intermediate mass numbers are more tightly bound and more numbers are more tightly bound and more stable than those with either smaller or stable than those with either smaller or larger mass numberslarger mass numbers

Nuclear Binding EnergyNuclear Binding Energy►Trend shows that:Trend shows that:

Heavy nuclei gain stability and split into two Heavy nuclei gain stability and split into two mid-sized nucleimid-sized nuclei

►Known as Known as FISSIONFISSION►Used to generate energy in nuclear power plantsUsed to generate energy in nuclear power plants

Greater amounts of energy are released if very Greater amounts of energy are released if very light are light are fusedfused together to form a more together to form a more massive nucleimassive nuclei

►Known as Known as FUSIONFUSION►is an essential energy-producing process in the Sunis an essential energy-producing process in the Sun

Outside SourcesOutside Sources►http://chemistry.about.com/od/http://chemistry.about.com/od/

workedchemistryproblems/a/workedchemistryproblems/a/nukerxns.htmnukerxns.htm

►http://wps.pearsoncustom.com/http://wps.pearsoncustom.com/pcp_brown_chemistry_10/34/8909/228pcp_brown_chemistry_10/34/8909/2280844.cw/index.html0844.cw/index.html

Susanna Trost Kelsey

Mariner

•Natural and artificial sourcesNatural and artificial sources•Sun gives off infrared, ultraviolet, & visible radiationSun gives off infrared, ultraviolet, & visible radiation•Television and radio stations give off radio waves Television and radio stations give off radio waves •Microwaves ovens give off microwavesMicrowaves ovens give off microwaves•Medical procedures can give off X-raysMedical procedures can give off X-rays•Natural materials like soil can have radio activityNatural materials like soil can have radio activity

EVERYDAY LIFEEVERYDAY LIFE

•Excitation is when excited electrons are moved to a higher Excitation is when excited electrons are moved to a higher energy state or the motion of molecules is increased as a energy state or the motion of molecules is increased as a result of absorbed radiationresult of absorbed radiation•Ionization is when an electron is removed from a molecule or Ionization is when an electron is removed from a molecule or atom by radiationatom by radiation

•Ionizing radiation: radiation that causes ionization, can ionize Ionizing radiation: radiation that causes ionization, can ionize waterwater•Non-ionizing radiation: radiation that does not cause ionization Non-ionizing radiation: radiation that does not cause ionization and has a lower energyand has a lower energy

MATTER ABSORBING MATTER ABSORBING RADIATIONRADIATION

•Free Radical: A substance with one or more unpaired Free Radical: A substance with one or more unpaired electronselectrons• OH molecule is a highly reactive and unstable free radicalOH molecule is a highly reactive and unstable free radical

•Free radicals attack surrounding biomolecules which Free radicals attack surrounding biomolecules which produces new free radicalsproduces new free radicals•One free radical can cause many chemical reactions One free radical can cause many chemical reactions disrupting normal cell operationsdisrupting normal cell operationsHH22OO++ + H + H22O HO H33OO++ + OH + OH

•Based on energy and activity of radiation, location of Based on energy and activity of radiation, location of source, and length of exposuresource, and length of exposure•Gamma rays and X-rays can penetrate human tissueGamma rays and X-rays can penetrate human tissue•The skin stops alpha raysThe skin stops alpha rays

•If within the body, they can transfer energy to surrounding If within the body, they can transfer energy to surrounding tissues causing damagetissues causing damage

•Beta rays penetrate only 1 cm into the skinBeta rays penetrate only 1 cm into the skin•Tissues that rapidly reproduce show the most Tissues that rapidly reproduce show the most damagedamage

•Examples: Lymph nodes, bone marrow, and blood forming Examples: Lymph nodes, bone marrow, and blood forming tissuestissues

•Prolong exposure to radiation may lead to cancerProlong exposure to radiation may lead to cancer•Damage to a cells growth-regulation mechanism causes a Damage to a cells growth-regulation mechanism causes a cell to rapidly and uncontrollably reproducecell to rapidly and uncontrollably reproduce•Leukemia is most associated with radiation (excessive Leukemia is most associated with radiation (excessive growth of white blood cells)growth of white blood cells)

DAMAGING RADIATION DAMAGING RADIATION

•Gray and Rad are units to measure radiation exposureGray and Rad are units to measure radiation exposure

•Gray (Gy): the SI unit of absorbed doseGray (Gy): the SI unit of absorbed dose•One joule per kilogram of tissueOne joule per kilogram of tissue

• •Rad (Rad (rradiation adiation aabsorbed bsorbed ddose): 1 x 10ose): 1 x 10-2-2 joule of energy per joule of energy per kilogram of tissuekilogram of tissue

• 1 Gy = 100 rad1 Gy = 100 rad

•Rad is the most common Rad is the most common

RADIATION DOSESRADIATION DOSES

•Different types of radiation harm biological materials differentlyDifferent types of radiation harm biological materials differently•RBERBE is a multiplication factor that measures the relative biological is a multiplication factor that measures the relative biological damage caused by radiationdamage caused by radiation

•Multiplied by the radiation dose to correct the differences in radiation Multiplied by the radiation dose to correct the differences in radiation damagedamage

• changes with total dose, dose rate and the type of tissue affectchanges with total dose, dose rate and the type of tissue affect•About 1 for beta and gamma radiationAbout 1 for beta and gamma radiation•About 10 for alpha radiation About 10 for alpha radiation

•Rem (roentgen equivalent for man): unit for effective dosage, Rem (roentgen equivalent for man): unit for effective dosage, more commonly usedmore commonly used•Sievert (Sv) is the SI unit for effective dosageSievert (Sv) is the SI unit for effective dosage

•1 Sv = 100 rem1 Sv = 100 rem

RRELATIVE ELATIVE BBIOLOGICAL IOLOGICAL EEFFECTIVENESSFFECTIVENESS

# of rems = (# of rads)(RBE)(gray)(RBE) = Sv

•Radioactive noble gasRadioactive noble gas•Radon-222 is caused from Radon-222 is caused from nuclear disintegration series of nuclear disintegration series of Uranium-238 Uranium-238 •Created in soil and rock decays Created in soil and rock decays as uraniumas uranium•Accounts for large percentage of Accounts for large percentage of our exposure to radiationour exposure to radiation•Does not chemically react as it Does not chemically react as it escapes from the groundescapes from the ground

•Because it is extremely Because it is extremely unreactiveunreactive

• Has a very short half lifeHas a very short half life•Combined with its high RBE, Combined with its high RBE, radon is a probable cause of lung radon is a probable cause of lung cancer when inhaledcancer when inhaled

RADON-222RADON-222

• High-energy radiation is used to damage the DNA of High-energy radiation is used to damage the DNA of cancer cells, which kills the cellscancer cells, which kills the cells

•Normal cells can also be damaged, so treatment is done Normal cells can also be damaged, so treatment is done very carefully very carefully

•Cancer cells more likely to be damaged because rapidly Cancer cells more likely to be damaged because rapidly reproducing cells are very vulnerable to radiation damagereproducing cells are very vulnerable to radiation damage

•Radiation can come from a machine or radioactive Radiation can come from a machine or radioactive material can be injected into the bloodstream or placed material can be injected into the bloodstream or placed directly in the body near the tumor cellsdirectly in the body near the tumor cells

•Gamma rays, x-rays and charged Gamma rays, x-rays and charged particles can be usedparticles can be usedRADIATION THERAPYRADIATION THERAPY

http://www.cancer.gov/cancertopics/factsheet/http://www.cancer.gov/cancertopics/factsheet/Therapy/radiationTherapy/radiation

SOURCESSOURCES

http://www.google.com/imgres?q=wave

http://www.nrc.gov/reading-rm/doc-collections/fact-sheets/bio-effects-radiation.html

Chemistry The Central Science Textbook

2.1 Radioactivity2.1 RadioactivityBy: Margo FoxBy: Margo Fox

ReviewReview►Nucleons- both protons and Nucleons- both protons and

neutronneutron►All atoms:All atoms:

Same # of protons (atomic #)Same # of protons (atomic #) Can have different # of Can have different # of

neutronsneutrons►Mass number- total # of Mass number- total # of

nucleons in nucleus nucleons in nucleus Same atomic # but different Same atomic # but different

mass number- isotopesmass number- isotopes

IsotopesIsotopes►Uranium-235 or UUranium-235 or U►Different natural abundancesDifferent natural abundances►Different stabilitiesDifferent stabilities►Nuclide- nucleus with specified # of Nuclide- nucleus with specified # of

protons and neutronsprotons and neutrons►Radionuclides- radioactive nucleiRadionuclides- radioactive nuclei►Radioisotopes- atoms containing those Radioisotopes- atoms containing those

nucleinuclei

23592

Nuclear EquationsNuclear Equations►Radionuclides- unstable, Radionuclides- unstable,

spontaneously emit particles and spontaneously emit particles and electromagnetic radiation electromagnetic radiation

►Emit radiation to become more stableEmit radiation to become more stable►Emitted radiation is carrier of the Emitted radiation is carrier of the

excess energyexcess energy

Nuclear EquationsNuclear Equations►Ex: Uranium-238 and helium-4Ex: Uranium-238 and helium-4

Helium-4 particles are known as alpha particles Helium-4 particles are known as alpha particles Alpha radiation- stream of alpha particlesAlpha radiation- stream of alpha particles 238 234 4 238 234 4 92 90 292 90 2 radioactive decay and alpha decayradioactive decay and alpha decay 238 = 234 + 4238 = 234 + 4 92 = 90 + 292 = 90 + 2 Must be balancedMust be balanced

U Th He

Types of Radioactive DecayTypes of Radioactive DecayProperty a (Alpha) Β (Beta) ϒ (Gamma)

Charge 2+ 1- 0

Mass 6.64 * 10^-24g 9.11 * 10^-28g 0

Relative penetrating power

1 100 10,000

Nature of radiation

He nuclei Electrons

High-energy protons 4

2

Beta RadiationBeta Radiation►Beta particles- high speed electrons Beta particles- high speed electrons

emitted by an unstable nucleus emitted by an unstable nucleus 0 00 0 -1 -1 -1 -1

1 1 01 1 00 1 -10 1 -1

e or β

n p + e

Gamma Radiation (Gamma Gamma Radiation (Gamma Rays)Rays)

►High-energy photons (electromagnetic High-energy photons (electromagnetic radiation of very short wavelength)radiation of very short wavelength)

►Does noDoes not change atomic # or mass #t change atomic # or mass #►Represents the energy lost when Represents the energy lost when

remaining nucleons reorganize to be remaining nucleons reorganize to be more stablemore stable

►Generally not shown when writing Generally not shown when writing equationsequations

Positron Emission Positron Emission ►Same mass as an electron, but Same mass as an electron, but

opposite chargeopposite charge

►Converts proton to neutron and Converts proton to neutron and decreases atomic number by 1decreases atomic number by 1

Electron CaptureElectron Capture►The capture by the nucleus of an The capture by the nucleus of an

electron from the electron cloud electron from the electron cloud surrounding the nucleussurrounding the nucleus

►Shown on reactant side because the Shown on reactant side because the electron is consumed not formed in electron is consumed not formed in the processthe process

►Converts proton to neutron Converts proton to neutron

Further ResearchFurther Research►Positron Emission Tomography Scan- imaging Positron Emission Tomography Scan- imaging

test to help reveal how tissues and organs are test to help reveal how tissues and organs are functioningfunctioning Inject, swallow, or inhale radioactive material Inject, swallow, or inhale radioactive material Accumulates in areas with higher levels of chemical Accumulates in areas with higher levels of chemical

activity (areas of disease)activity (areas of disease)

►Gamma Knife TherapyGamma Knife Therapy treatment using gamma rays, a type of high-energy treatment using gamma rays, a type of high-energy

radiation that can be tightly focused on small tumors radiation that can be tightly focused on small tumors or other lesions in the head or neck, so very little or other lesions in the head or neck, so very little normal tissue receives radiationnormal tissue receives radiation

What Type of RadiationWhat Type of Radiation

116

11 5

01

8137

8136

0-1

Bibliography Bibliography ►http://www.cancer.gov/dictionary?http://www.cancer.gov/dictionary?

cdrid=46396cdrid=46396►http://www.mayoclinic.com/health/pet-http://www.mayoclinic.com/health/pet-

scan/MY00238scan/MY00238

By A Stormy Hickey and By A Stormy Hickey and The Austin McCaddenThe Austin McCadden

Detection of Detection of RadioactivityRadioactivity

Discovery of RadiationDiscovery of Radiation

Was discovered by Was discovered by Henri BecquerelHenri Becquerel

Observed effect of Observed effect of radiation on radiation on photographic platesphotographic plates

Received 1903 Nobel Received 1903 Nobel Prize for his worksPrize for his works

SI unit for expressing SI unit for expressing radiation activity was radiation activity was named becquerel (Bq)named becquerel (Bq)

Effects of radiationEffects of radiation

Radiation affects Radiation affects photographic film photographic film the same way it the same way it does X-raysdoes X-rays

Increased radiation Increased radiation darkens negative darkens negative are on filmare on film

Used by people Used by people who work with who work with radiation to see radiation to see extent of exposureextent of exposure

Ways of DetectionWays of Detection

►Geiger counterGeiger counter detects and detects and

measures measures radioactivityradioactivity

Use is based on the Use is based on the ionization of matter ionization of matter caused by radiationcaused by radiation

Ions and electrons Ions and electrons permit conduction permit conduction of electrical currentof electrical current

Geiger Counter Geiger Counter

►Consists of a metal tube filled with gasConsists of a metal tube filled with gas►Tube has a “window” that can be infiltrated Tube has a “window” that can be infiltrated

by alpha, beta, or gamma raysby alpha, beta, or gamma rays►Wire in tube connected to a source of Wire in tube connected to a source of

direct current direct current ►Current flows between the wire and tube Current flows between the wire and tube

when ions are produced by entering when ions are produced by entering radiationradiation

►Records pulses that indicate presence of Records pulses that indicate presence of radiationradiation

Other Indicators of Other Indicators of RadiationRadiation

►Phosphors-Phosphors- excited by excited by

radiation give off radiation give off light when light when electrons return to electrons return to lower-energy lower-energy statesstates

Ex: Zinc sulfide is Ex: Zinc sulfide is excited by alpha excited by alpha particlesparticles

Scintillation CounterScintillation Counter

Measures radiation Measures radiation based on tiny flashes based on tiny flashes of light of light

Flashes of light Flashes of light produced when produced when radiation strikes a radiation strikes a phosphor that’s phosphor that’s suitablesuitable

Flashes are Flashes are magnified magnified electronically and electronically and counted to measure counted to measure radiationradiation

RadioisotopesRadioisotopes

►Radioisotopes can Radioisotopes can be detected readily, be detected readily, used to follow used to follow element through element through chemical reactionschemical reactions Possible because all Possible because all

isotopes of an isotopes of an element have element have essentially identical essentially identical chemical propertieschemical properties

Radioisotopes ContinuedRadioisotopes Continued

►When small amounts of radioisotopes When small amounts of radioisotopes are mixed with the naturally are mixed with the naturally occurring stable isotopes, all isotopes occurring stable isotopes, all isotopes go through same reaction togethergo through same reaction together

►Element can be tracked in reaction or Element can be tracked in reaction or process by tracing radioactivityprocess by tracing radioactivity

►Because Radioisotopes trace paths of Because Radioisotopes trace paths of element they are called Radiotracerselement they are called Radiotracers

Additional ResearchAdditional ResearchGold Leaf ElectroscopeGold Leaf Electroscope► When electroscope is When electroscope is

charged, the gold leaf charged, the gold leaf sticks out, because sticks out, because charges on gold repel charges on gold repel charges on metal stalkcharges on metal stalk

► Radiation ionizes air, Radiation ionizes air, and conducts electricity and conducts electricity

The charge leaks away The charge leaks away from electroscope, from electroscope, discharging it and the gold discharging it and the gold leaf falls.leaf falls.

Additional Research Cont.Additional Research Cont.► Personal radiation Personal radiation

detectors can be detectors can be purchased at a relatively purchased at a relatively low pricelow price

PDS-100GPDS-100GSensitive Survey MeterSensitive Survey Meter

QuestionsQuestions

How did Becquerel discover radiation?How did Becquerel discover radiation?

How can Radioisotopes be used to How can Radioisotopes be used to track the path of an element?track the path of an element?

SourcesSourceshttp://www.darvill.clara.net/nucrad/http://www.darvill.clara.net/nucrad/

detect.htmdetect.htm

http://www.mirion-hp.com/http://www.mirion-hp.com/portableinstruments.asp?_kk=detectionportableinstruments.asp?_kk=detection%20of%20radioactivity&_kt=43082093-%20of%20radioactivity&_kt=43082093-d735-446c-87b0-d735-446c-87b0-366f3477100f&gclid=CMCRpffE4q4CFYuK366f3477100f&gclid=CMCRpffE4q4CFYuK4Aod7G9bZw4Aod7G9bZw

21.8 Nuclear Fusion21.8 Nuclear FusionStephanie ChoStephanie ChoAbigail WangAbigail Wang

What is nuclear fusion?What is nuclear fusion?

►Light nuclei Light nuclei fuse into larger fuse into larger ones ones produces produces energyenergy

►Take place on Take place on the Sun (mostly the Sun (mostly H and He)H and He)

Fusion as an Energy SourceFusion as an Energy Source►Appealing due toAppealing due to

1. Availability of light isotopes1. Availability of light isotopes 2. Products are not usually radioactive2. Products are not usually radioactive

►Still, not used presentlyStill, not used presently►Requires high energies to overcome Requires high energies to overcome

repulsionrepulsion high temps needed high temps needed

Fusion as an Energy Source Fusion as an Energy Source

► Thermonuclear Thermonuclear reactionsreactions

► Lowest temp needed Lowest temp needed for any fusion requires for any fusion requires 40,000,000 K40,000,000 K

► Temps have been Temps have been achieved with atomic achieved with atomic bomb to begin processbomb to begin process

► Unacceptable for Unacceptable for controlled power controlled power generationgeneration

Problems and ResearchProblems and Research

► No known structural No known structural material is known to material is known to withstand temperatureswithstand temperatures

► Researching to generate Researching to generate high temperaturehigh temperature Tokamak - an apparatus Tokamak - an apparatus

for producing controlled for producing controlled fusion reactions in hot fusion reactions in hot plasmaplasma

► Strong magnetic fieldsStrong magnetic fields► Up to 3,000,000K can be Up to 3,000,000K can be

generated, but still not generated, but still not enoughenough

Use of powerful lasersUse of powerful lasers

Inertial ConfinementInertial Confinement

► LasersLasers► Direct driveDirect drive

Lasers focused on small Lasers focused on small deuterium-tritium pelletdeuterium-tritium pellet

Compresses inwardsCompresses inwards shock waveshock wave heat heat

► Indirect driveIndirect drive National Ignition FacilityNational Ignition Facility Hohlraum is heated by Hohlraum is heated by

192 beams192 beams X-rays X-rays heat pelletheat pellet

Plasma and Plasma and compressioncompression

1010-11-11 to 10 to 10-9-9 seconds seconds

Magnetic ConfinementMagnetic Confinement

► Magnetic fields used to Magnetic fields used to contain the charged contain the charged particles composed of particles composed of plasmaplasma Contains plasma for a Contains plasma for a

long time at low densitylong time at low density► Two typesTwo types

MirrorMirror► Electric current Electric current

generates a magnetic generates a magnetic fieldfield

► Contains the plasma Contains the plasma inside the magnetic fieldinside the magnetic field

► Open typeOpen type Toroidal/TokamakToroidal/Tokamak

► Closed typeClosed type Coils’ magnetic field Coils’ magnetic field

and magnetic current and magnetic current created by plasma created by plasma counteractscounteracts

By Jin Lee and Paul GregotskiBy Jin Lee and Paul GregotskiAnd Special Appearances And Special Appearances

from:from:Hannah Cherry and Kayla Hannah Cherry and Kayla

SeiderSeider

What is a Nuclear What is a Nuclear Transmutation?Transmutation?

►A nucleus can also change identity if it is truck A nucleus can also change identity if it is truck by a neutron or by another nucleus. Nuclear by a neutron or by another nucleus. Nuclear reactions that are induced in this way are reactions that are induced in this way are known as known as nuclear transmutations.nuclear transmutations.

►The first conversion of on nucleus into another The first conversion of on nucleus into another was performed in 1919 by Ernest Rutherford. was performed in 1919 by Ernest Rutherford.

►He succeeded in converting nitrogen-14 into He succeeded in converting nitrogen-14 into oxygen-17 plus a proton using high velocity oxygen-17 plus a proton using high velocity alpha particles emitted by radium.alpha particles emitted by radium.

►Reaction: 14/7 N + 4/2 H --Reaction: 14/7 N + 4/2 H -- 17/8 O + 1/1 H 17/8 O + 1/1 H

What type of Particles are What type of Particles are They?They?

►This reaction demonstrated the nuclear reactions can This reaction demonstrated the nuclear reactions can be induced by striking nuclei with particles such as be induced by striking nuclei with particles such as alpha particles. alpha particles.

►Such reactions made it possible to synthesize hundreds Such reactions made it possible to synthesize hundreds of radioisotopes in the lab.of radioisotopes in the lab.

►Nuclear transmutations are sometimes represented by Nuclear transmutations are sometimes represented by listing, in order, the target nucleus, the bombarding listing, in order, the target nucleus, the bombarding particle, the ejected particle, and the product nucleus. particle, the ejected particle, and the product nucleus.

►Written in this fashion is: 14/7 N (α,p) 17/8 OWritten in this fashion is: 14/7 N (α,p) 17/8 O►The alpha particle, proton, and neutron are abbreviated The alpha particle, proton, and neutron are abbreviated

as α, p, n.as α, p, n.

Charged ParticlesCharged Particles►Charged particles such as alpha particles must be Charged particles such as alpha particles must be

moving very fast in order to overcome the electrostatic moving very fast in order to overcome the electrostatic repulsions between them and the target nucleus. repulsions between them and the target nucleus.

►The higher the nuclear charge on either the projectile The higher the nuclear charge on either the projectile or the target, the faster the projectiles must be moving or the target, the faster the projectiles must be moving to bring about nuclear reactions. to bring about nuclear reactions.

►Many methods have been devised to accelerate Many methods have been devised to accelerate charged particles using strong magnetic and charged particles using strong magnetic and electrostatic fields.electrostatic fields.

► These particle accelerators are called These particle accelerators are called cyclotroncyclotron and and synchrotronsynchrotron. .

What is a Cyclotron?What is a Cyclotron?► Cyclotron:Cyclotron: the hollow D-shaped electrodes are the hollow D-shaped electrodes are

called “dees.” The projectiles particles are called “dees.” The projectiles particles are introduced into a vacuum chamber within the introduced into a vacuum chamber within the cyclotron. cyclotron.

► The particles are then accelerated by making the The particles are then accelerated by making the dees alternately positively and negatively charged. dees alternately positively and negatively charged.

► Magnets placed above and below the dees keep Magnets placed above and below the dees keep the particles moving in a spiral path until they are the particles moving in a spiral path until they are finally deflected out of the cyclotron and emerge finally deflected out of the cyclotron and emerge to strike a target substance. to strike a target substance.

► Particle accelerators have been used mainly to Particle accelerators have been used mainly to synthesize heavy elements and to investigate the synthesize heavy elements and to investigate the fundamental structure of matter.fundamental structure of matter.

Using NeutronsUsing Neutrons► Most synthetic isotope used in quantity in Most synthetic isotope used in quantity in

medicine and scientific research are made medicine and scientific research are made using neutrons as projectiles. using neutrons as projectiles.

► Because neutrons are neutral they are not Because neutrons are neutral they are not repelled by the nucleus. repelled by the nucleus.

► They do not need to be accelerated as do They do not need to be accelerated as do charged particles in order to cause nuclear charged particles in order to cause nuclear reactions. reactions.

► The necessary neutrons are produced by the The necessary neutrons are produced by the reactions that occur in nuclear reactors. reactions that occur in nuclear reactors.

► Cobalt-60 is used in radiation therapy where Cobalt-60 is used in radiation therapy where it is bombarded by neutrons.it is bombarded by neutrons.

► The following sequence takes place:The following sequence takes place: 58/26 Fe + 1/0 n ----58/26 Fe + 1/0 n ---- 59/26 Fe 59/26 Fe 59/26 Fe --59/26 Fe -- 59/27 Co + 0/-1 e 59/27 Co + 0/-1 e 59/27 Co + 1/0 n --59/27 Co + 1/0 n -- 60/27 Co 60/27 Co

Transuranium ElementsTransuranium Elements►Artificial transmutations have been used to produce Artificial transmutations have been used to produce

the elements with atomic number above 92.the elements with atomic number above 92.► These are known as These are known as transuranium elements transuranium elements

because they occur immediately following uranium because they occur immediately following uranium in the periodic table. in the periodic table.

►Elements 93, neptunium, and 94, plutonium were Elements 93, neptunium, and 94, plutonium were first discovered in 1940. They were produced by first discovered in 1940. They were produced by bombarding uranium-238 with neutrons:bombarding uranium-238 with neutrons: 238/92 U + 1/0 n 238/92 U + 1/0 n 239/92 239/92 239/93 Np + 0/-1 e 239/93 Np + 0/-1 e 239/93 Np 239/93 Np 239/94 Pu + 0/-1 e 239/94 Pu + 0/-1 e

Transmutation Elements Transmutation Elements (cont.)(cont.)

►Elements with larger atomic numbers are Elements with larger atomic numbers are normally formed in small quantities in particle normally formed in small quantities in particle accelerators. accelerators.

► In 1994 a team of European scientists synthesized In 1994 a team of European scientists synthesized element 111 by bombarding bismuth target for element 111 by bombarding bismuth target for several days with a bream of nickel atoms:several days with a bream of nickel atoms: 209/83 Bi + 64/28 NI 209/83 Bi + 64/28 NI 272/111 X + 1/0 n 272/111 X + 1/0 n

►The nuclei are very short-lived, and they undergo The nuclei are very short-lived, and they undergo alpha decay within milliseconds of their synthesis.alpha decay within milliseconds of their synthesis.

Equations:Equations:►Example: Carbon-11 is an example of an Example: Carbon-11 is an example of an

isotope that decays by positron emission:isotope that decays by positron emission:►The positron has a very short life because it The positron has a very short life because it

is annihilated when it collides with an is annihilated when it collides with an electron, producing gamma rays:electron, producing gamma rays:

►Electron capture is the capture by the Electron capture is the capture by the nucleus of an inner-shell electron from the nucleus of an inner-shell electron from the electron cloud surrounding the nucleus. electron cloud surrounding the nucleus.

Chart of Particles:Chart of Particles:

Particle SymbolNeutron 1/0 nProton 1/1 p or 1/1 H

Electron 0/-1 ePositron 0/1 e

Beta Particle 0/-1 e or 0/-1 βAlpha Particle 4/2 a or 4/2 He

Example Problem:Example Problem:Question: Balance the following equation:Question: Balance the following equation:

252/98 Cf + 10/5 B -252/98 Cf + 10/5 B - 3 (1/0 n) + ? 3 (1/0 n) + ?

Answer:Answer:252+10=262252+10=262 Cf+BCf+B Lr=103Lr=10398+5=10398+5=103

262-3=259262-3=259

259/103 Lr259/103 Lr

Questions:Questions:Question: Write a balanced equation for:Question: Write a balanced equation for:

106/46 Pd (a,p) 109/47 Ag106/46 Pd (a,p) 109/47 Ag

Question: Fill in the missing particle:Question: Fill in the missing particle:32/16 S + 1/0n 32/16 S + 1/0n 1/1 p + ? 1/1 p + ?

Question: Write a balanced equation for:Question: Write a balanced equation for:14/7N(p,a)11/6C14/7N(p,a)11/6C

Answers To Questions:Answers To Questions:Question: Write a balanced equation for:Question: Write a balanced equation for:

106/46 Pd (a,p) 109/47 Ag106/46 Pd (a,p) 109/47 Ag 106/46 Pd + 4/2 a 106/46 Pd + 4/2 a 1/1 p + 109/47 Ag 1/1 p + 109/47 Ag

Question: Fill in the missing particle:Question: Fill in the missing particle:32/16 S + 1/0n 32/16 S + 1/0n 1/1 p + ? 1/1 p + ? 32/16 S + 1/0n 32/16 S + 1/0n 1/1 p + 32/15 P 1/1 p + 32/15 P

Question: Write a balanced equation for:Question: Write a balanced equation for:14/7N(p,a)11/6C14/7N(p,a)11/6C14/7 N + 1/1 p 14/7 N + 1/1 p 4/2 a + 11/6 C 4/2 a + 11/6 C

BibliographyBibliography►http://faculty.ncc.edu/LinkClick.aspx?http://faculty.ncc.edu/LinkClick.aspx?

fileticket=Fkhb0_AcPfEfileticket=Fkhb0_AcPfE%3D&tabid=1920%3D&tabid=1920

►http://www.avon-chemistry.com/http://www.avon-chemistry.com/nuclear_lec.htmlnuclear_lec.html

►Chemistry (The Central Science) Chemistry (The Central Science) Brown LeMay BurstenBrown LeMay Bursten

21.321.3Nuclear Nuclear

TransmutationsTransmutationsBy Dakota Lieske By Dakota Lieske & Cindy Rushworth& Cindy Rushworth

What are Nuclear What are Nuclear Transmutations?Transmutations?► Nuclear transmutations are nuclear Nuclear transmutations are nuclear

reactions that are caused by a nucleus reactions that are caused by a nucleus being struck by either a neutron or being struck by either a neutron or another nucleusanother nucleus

► The result of this is a change in the The result of this is a change in the nucleus’s identitynucleus’s identity

Ernest Rutherford’s First Ernest Rutherford’s First ConversionConversion

►Ernest Rutherford performed the first nuclear Ernest Rutherford performed the first nuclear transmutation in 1919, converting nitrogen-14 transmutation in 1919, converting nitrogen-14 to oxygen-17 and a protonto oxygen-17 and a proton

►To do this, he used high-velocity alpha To do this, he used high-velocity alpha particles emitted by radiumparticles emitted by radium

►This proved that by striking nuclei with alpha This proved that by striking nuclei with alpha particles or anything of the like, nuclear particles or anything of the like, nuclear reactions can be created reactions can be created

Shorthand NotationShorthand Notation►Nuclear Transmutations can be listed in Nuclear Transmutations can be listed in

shorthand notation by listing, in order, the target shorthand notation by listing, in order, the target nucleus, the bombarding particle, the ejected nucleus, the bombarding particle, the ejected particle, and the product nucleusparticle, and the product nucleus

Target Nucleus

Bombarding Particle

Ejected Particle

Product NucleusComma

*Neutrons will be abbreviated as n*Protons will be abbreviated as p

*Alpha Particles will be abbreviated as

Charged ParticlesCharged Particles►Charged particles (those such as alpha particles) Charged particles (those such as alpha particles)

must be moving extremely fast so that it can must be moving extremely fast so that it can overcome the electrostatic repulsion between overcome the electrostatic repulsion between them and the target nucleusthem and the target nucleus

►Particle accelerators are made to accelerate the Particle accelerators are made to accelerate the charged particles by using strong magnetic and charged particles by using strong magnetic and electrostatic fieldselectrostatic fields

►Particle accelerators have been used in order to Particle accelerators have been used in order to synthesize heavy elements, investigate synthesize heavy elements, investigate fundamental structures of matter, and fail at fundamental structures of matter, and fail at creating black holes creating black holes

Neutrons Neutrons ►Most isotopes are made using neutrons as Most isotopes are made using neutrons as

projectiles in nuclear transmutations; they projectiles in nuclear transmutations; they do not need to be accelerated in order to do not need to be accelerated in order to cause nuclear reactions, as they are neutral cause nuclear reactions, as they are neutral and therefore not repelled by the nucleusand therefore not repelled by the nucleus

►For the reaction in which Iron-58 is For the reaction in which Iron-58 is bombarded by neutrons to create Cobalt-60, bombarded by neutrons to create Cobalt-60, the following sequence takes place…the following sequence takes place…

5826

26

26

27

27

27

5959

59

60

1

1-1

00

0

FeFeFe

CoCo

Co n

ne

++

+

59

Transuranium ElementsTransuranium Elements►Transmutations are often used to produce Transmutations are often used to produce

elements with an atomic number above 92elements with an atomic number above 92►These elements are called “Transuranium These elements are called “Transuranium

Elements” as they occur after uranium on Elements” as they occur after uranium on the periodic tablethe periodic table

►Elements such as neptunium and Elements such as neptunium and plutonium were discovered through this in plutonium were discovered through this in 1940 by bombarding uranium-238 with 1940 by bombarding uranium-238 with neutronsneutrons

Patterns of Nuclear Patterns of Nuclear StabilityStability

By Courtney Walker and Kelli By Courtney Walker and Kelli JoergerJoerger

Stability of a NucleusStability of a Nucleus►Not one single rule to determine if Not one single rule to determine if

nucleus is radioactivenucleus is radioactive Variety of factorsVariety of factors

►Observations can help predict stability Observations can help predict stability of nucleusof nucleus

Neutron-to-Proton RatioNeutron-to-Proton Ratio► Strong nuclear forceStrong nuclear force

Attraction between nucleonsAttraction between nucleons► Neutrons bind nucleus togetherNeutrons bind nucleus together

All nuclei with at least 2 protons contain a All nuclei with at least 2 protons contain a neutronneutron

► Nuclei up to atomic number 20 have equal Nuclei up to atomic number 20 have equal protons and neutronsprotons and neutrons As exceeding this number, more neutrons than As exceeding this number, more neutrons than

protonsprotons► Neutron-to-proton ratios of stable nuclei Neutron-to-proton ratios of stable nuclei

increase with increasing atomic numberincrease with increasing atomic number

Belt of Stability ChartBelt of Stability Chart

* All nuclei with 84 or more protons are radioactive

Type of Radioactive DecayType of Radioactive Decay►Depends on neutron-to-proton ratio Depends on neutron-to-proton ratio

compared to nearby nuclei in belt of compared to nearby nuclei in belt of stabilitystability

►3 possible situations3 possible situations

Situation #1: AboveSituation #1: Above►Nuclei above belt of stabilityNuclei above belt of stability►High neutron-to-proton ratioHigh neutron-to-proton ratio►Capable of lowering ratio by emitting a Capable of lowering ratio by emitting a

beta particlebeta particle►Beta emissions- decrease number of Beta emissions- decrease number of

neutrons and increase number of neutrons and increase number of protons in nucleusprotons in nucleus

Situation #2: BelowSituation #2: Below► Nuclei below belt of stabilityNuclei below belt of stability► Low neutron-to-proton ratioLow neutron-to-proton ratio► Capable of increasing ratio by positron Capable of increasing ratio by positron

emission or electron captureemission or electron capture► Both increase number of neutrons and Both increase number of neutrons and

decrease number of protonsdecrease number of protons► Positron emission more common in Positron emission more common in

lighter nucleilighter nuclei► Electron capture more common as Electron capture more common as

nuclear charge increasesnuclear charge increases

Situation #3: Above 84Situation #3: Above 84►Nuclei with atomic numbers greater Nuclei with atomic numbers greater

than or equal to 84than or equal to 84►Heavy nucleiHeavy nuclei

Beyond belt of stabilityBeyond belt of stability►Alpha emission- decreases number of Alpha emission- decreases number of

neutrons and number of protons by 2neutrons and number of protons by 2►Nucleus diagonally toward belt of Nucleus diagonally toward belt of

stabilitystability

Sample Exercise: 21.3Sample Exercise: 21.3

Sample Exercise: 21.3Sample Exercise: 21.3B. Predict the mode of decay of (b) xenon- B. Predict the mode of decay of (b) xenon- 118.118.

Sample Exercise 21.3Sample Exercise 21.3B. Predict the mode of decay of (b) B. Predict the mode of decay of (b) xenon- 118.xenon- 118.

- Xenon has an atomic number of 54, and 118-54= 64 - Xenon has an atomic number of 54, and 118-54= 64 neutrons giving it a neutron-to-proton ratio of 64/54= 1.2.neutrons giving it a neutron-to-proton ratio of 64/54= 1.2.

- According to the belt of stability, stable nuclei usually - According to the belt of stability, stable nuclei usually have higher neutron to proton ratios than xenon- 118. have higher neutron to proton ratios than xenon- 118.

-The nucleus can increase this ratio by either positron -The nucleus can increase this ratio by either positron emission or electron capture.emission or electron capture.Both modes of decay are observed. Both modes of decay are observed.

Radioactive SeriesRadioactive Series

► Some nuclei cannot become stable with only Some nuclei cannot become stable with only one emissionone emission Therefore a series of successive emissions occurTherefore a series of successive emissions occur

► Also called nuclear disintegration seriesAlso called nuclear disintegration series Series of nuclear reactions that begins with an Series of nuclear reactions that begins with an

unstable nucleus and terminates with a stable unstable nucleus and terminates with a stable oneone

► Examples include Examples include Starts with uranium-238 and ends with lead-206 Starts with uranium-238 and ends with lead-206 Starts with uranium 235 and ends with lead-207Starts with uranium 235 and ends with lead-207 Starts with thorium-232 and ends with lead-208Starts with thorium-232 and ends with lead-208

Radioactive Series of Uranium-Radioactive Series of Uranium-238238

Additional ObservationsAdditional Observations►Magic Number- more stableMagic Number- more stable

Nuclei with 2, 8, 20, 28, 50, or 82 protons Nuclei with 2, 8, 20, 28, 50, or 82 protons Nuclei with 2, 8, 20, 28, 50, 82, or 126 neutronsNuclei with 2, 8, 20, 28, 50, 82, or 126 neutrons

►Nuclei with even numbers of both protons Nuclei with even numbers of both protons and neutrons generally more stable than and neutrons generally more stable than those with odd numbers of nucleonsthose with odd numbers of nucleons

►Shell model of the nucleus analogous to Shell model of the nucleus analogous to stable closed –shell electron configurations stable closed –shell electron configurations

Number of Stable Isotopes

Protons Neutrons

157 Even Even

53 Even Odd

50 Odd Even

5 Odd Odd

Sample Exercise 21.4Sample Exercise 21.4

Additional ResearchAdditional Research►http://www.youtube.com/watch?http://www.youtube.com/watch?

v=VJZuY3_aLnI v=VJZuY3_aLnI ►http://www.youtube.com/watch?http://www.youtube.com/watch?

v=oFdR_yMKOCw&feature=related **v=oFdR_yMKOCw&feature=related **

Review GameReview Game1. Provide an explanation for why 1. Provide an explanation for why neutrons are needed in the nucleus. neutrons are needed in the nucleus.

AnswerAnswer►Positive Particles repel each other, and Positive Particles repel each other, and

multiple positive particles in the multiple positive particles in the nucleus needs something to keep that nucleus needs something to keep that mass together. Neutrons do this mass together. Neutrons do this because they have no charge and are because they have no charge and are able to balance out the positive charge able to balance out the positive charge of the protons. of the protons.

Review GameReview Game2. What type of particle is emitted 2. What type of particle is emitted when:when:

a. The neutron to proton ratio is higha. The neutron to proton ratio is highb. The neutron to proton ratio is lowb. The neutron to proton ratio is lowc. The atomic number is above 84?c. The atomic number is above 84?

AnswerAnswera.a. A beta particle is emittedA beta particle is emittedb.b. Either a positron emission or electron Either a positron emission or electron

capturecapturec.c. An alpha particle is emittedAn alpha particle is emitted

Review Game Review Game 3. Describe Nuclear Disintegration 3. Describe Nuclear Disintegration Series Series

AnswerAnswer► Initially begins with an unstable Initially begins with an unstable

nucleus that becomes stable through nucleus that becomes stable through emitting multiple particles and results emitting multiple particles and results in a stable one. in a stable one.

Review GameReview Game4. Define the meaning of a magic 4. Define the meaning of a magic number. number.

AnswerAnswer►A nucleus that involves a magic A nucleus that involves a magic

number is more stable than a nucleus number is more stable than a nucleus without a magic number.without a magic number.

►Nuclei with 2, 8, 20, 28, 50, or 82 Nuclei with 2, 8, 20, 28, 50, or 82 protons protons

►Nuclei with 2, 8, 20, 28, 50, 82, or 126 Nuclei with 2, 8, 20, 28, 50, 82, or 126 neutronsneutrons

Bonus: Worth the rest of the bag Bonus: Worth the rest of the bag of candy.of candy.

►Reiterate how you can predict a Reiterate how you can predict a method of decay when given an method of decay when given an element and its atomic number.element and its atomic number.

Rates of Radioactive Decay Rates of Radioactive Decay Steph Coyle and Rachel SacchettiSteph Coyle and Rachel Sacchetti

What is Radioactive Decay? What is Radioactive Decay? ► Spontaneous breakdown of an atomic Spontaneous breakdown of an atomic

nucleus nucleus ► Results in the release of energy and Results in the release of energy and

matter from the nucleusmatter from the nucleus

Half Half LifeLife► Decay= first order kinetic processDecay= first order kinetic process► Half-Life-Half-Life- time required for ½ of any time required for ½ of any

given quantity of a substance to react given quantity of a substance to react Constant rateConstant rate

► Less and less mass Less and less mass is lost at the point of is lost at the point of each half life each half life

Half-Life (cont.)Half-Life (cont.)► Short as millionth of a second- billions of yearsShort as millionth of a second- billions of years

Quick decay; not found in nature (synthesized)Quick decay; not found in nature (synthesized)► Unaffected by temp., pressure, or state of Unaffected by temp., pressure, or state of

chemical combinationchemical combination► Cannot be made harmless via chemical rxnCannot be made harmless via chemical rxn

Alpha and Beta DecayAlpha and Beta Decay

Radiocarbon-dating TechniqueRadiocarbon-dating Technique► Assumed carbon-14 to carbon-12 has been Assumed carbon-14 to carbon-12 has been

constant for 50,000 yrconstant for 50,000 yr► Carbon-14 in atmosphereCarbon-14 in atmosphere

photosynthesisphotosynthesis plants eaten by plants eaten by animalsanimals carbon-14 incorporated in carbon-14 incorporated in organism make-uporganism make-up animal dies animal dies Ratio of C-14 to C-12 decrease, and when Ratio of C-14 to C-12 decrease, and when

compared to ratio in atmosphere, can estimate compared to ratio in atmosphere, can estimate age of organismage of organism

Carbon Dating (cont.)Carbon Dating (cont.)

► 4.5x10^9 yrs for 4.5x10^9 yrs for Uranium-238 to decay Uranium-238 to decay to Lead-206 to Lead-206 Age of rocks containing Age of rocks containing

Uranium-238 can be Uranium-238 can be determined by looking at determined by looking at ratio U-238 to Pb-206ratio U-238 to Pb-206

► Oldest rocks 3x10^9 yrs Oldest rocks 3x10^9 yrs old old

Carbon Dating (cont.)Carbon Dating (cont.)

Calculating Rate of DecayCalculating Rate of Decay► Rate=Rate=kNkN

kk= decay constant = decay constant NN= number of radioactive nuclei= number of radioactive nuclei

► ActivityActivity- rate at which a sample decays - rate at which a sample decays Bq- becquerel, unit for expressing activity Bq- becquerel, unit for expressing activity Ci- Curie, 3.7x10^10Ci- Curie, 3.7x10^10

► Relationship between k and ½ life is k=0.693/ Relationship between k and ½ life is k=0.693/ t½ t½

Example Example ► 4.0 mCi sample of Co-60 undergoes 4.0 mCi sample of Co-60 undergoes

(4.0x10^10-3) x (3.7x10^10) = 1.5x10^8 (4.0x10^10-3) x (3.7x10^10) = 1.5x10^8 disintegrations per seconddisintegrations per second Therefore 1.5x10^8 Bq Therefore 1.5x10^8 Bq

Further ResearchFurther Research► Radioactivity was discovered in 1896 by the Radioactivity was discovered in 1896 by the

French scientist Henri BecquerelFrench scientist Henri Becquerel Hence Bq SI unit Hence Bq SI unit

► Working with phosphorescent materials, noticed Working with phosphorescent materials, noticed they glowed in dark after exposure to light they glowed in dark after exposure to light

More ResearchMore Research► Wrapped photographic plate in black paper and Wrapped photographic plate in black paper and

placed phosphorescent salts on paperplaced phosphorescent salts on paper► No resultNo result► Placed uranium salts on plate, blackened the platePlaced uranium salts on plate, blackened the plate► Radiations called Becquerel Rays Radiations called Becquerel Rays

Quiz!Quiz!► What is a half life?What is a half life?

Time required for ½ of any given quantity Time required for ½ of any given quantity of a substance to react of a substance to react

► What is radioactive decay?What is radioactive decay? Spontaneous breakdown of an atomic Spontaneous breakdown of an atomic

nucleus nucleus ► How does temperature affect decay? How does temperature affect decay?

It doesn’t It doesn’t

Quiz!Quiz!► True or false, radiocarbon-dating can be used to True or false, radiocarbon-dating can be used to

date a rockdate a rock FalseFalse

► What is the rate equation?What is the rate equation? Rate=kNRate=kN

► How old is the oldest rock? How old is the oldest rock? 3x10^93x10^9

Work CitedWork Cited► http://www.ndted.org/EducationResources/http://www.ndted.org/EducationResources/

HighSchool/Radiography/radioactivedecay.htmHighSchool/Radiography/radioactivedecay.htm► http://www.dummies.com/how-to/content/nuclear-http://www.dummies.com/how-to/content/nuclear-

chemistry-halflives-and-radioactive-dating.htmlchemistry-halflives-and-radioactive-dating.html► http://www.nobelprize.org/nobel_prizes/physics/http://www.nobelprize.org/nobel_prizes/physics/

laureates/1903/becquerel-bio.html laureates/1903/becquerel-bio.html