Radioactivity:Radioactivity:The Study of Unstable The Study of Unstable

AtomsAtoms

Chapter 25Chapter 25

Wilhelm Conrad Wilhelm Conrad RoentgenRoentgen

On December 22 1895, this physicist On December 22 1895, this physicist "photographed" his wife's hand, "photographed" his wife's hand, revealing the unmistakable image of her revealing the unmistakable image of her skeleton, complete with wedding ring. skeleton, complete with wedding ring.

Roentgen's wife had placed her hand in Roentgen's wife had placed her hand in the path of X-rays which Roentgen the path of X-rays which Roentgen created by beaming an electron ray created by beaming an electron ray energy source onto a cathode tube. energy source onto a cathode tube.

He studied fluoresence and He studied fluoresence and phosphoresence.phosphoresence.

Antoine Henri Antoine Henri BecquerelBecquerel

Becquerel found that, while the phenomena of Becquerel found that, while the phenomena of fluorescence and phosphorescence had many fluorescence and phosphorescence had many similarities to each other and to X-rays, they also had similarities to each other and to X-rays, they also had important differences. important differences. – Fluorescence and X-rays stopped when the initiating Fluorescence and X-rays stopped when the initiating

energy source was haltedenergy source was halted– Phosphorescence continued to emit rays some time after Phosphorescence continued to emit rays some time after

the initiating energy source was removed. the initiating energy source was removed. – However, in all three cases, the energy was derived However, in all three cases, the energy was derived

initially from an outside source. initially from an outside source. In March of 1896, during a time of overcast weather, In March of 1896, during a time of overcast weather,

Becquerel found he couldn't use the sun as an initiating Becquerel found he couldn't use the sun as an initiating energy source for his experiments. energy source for his experiments. – He put his wrapped photographic plates away in a He put his wrapped photographic plates away in a

darkened drawer, along with some crystals containing darkened drawer, along with some crystals containing uranium. uranium.

– Much to his surprise, the plates were exposed during Much to his surprise, the plates were exposed during storage by invisible emanations from the uranium. storage by invisible emanations from the uranium.

– The emanations did not require the presence of an The emanations did not require the presence of an initiating energy source--the crystals emitted rays on their initiating energy source--the crystals emitted rays on their own! own!

The Curies: Lives Devoted The Curies: Lives Devoted to Researchto Research

Working in the Becquerel lab, Marie Curie and her husband, Pierre, Working in the Becquerel lab, Marie Curie and her husband, Pierre, began what became a life long study of radioactivity. began what became a life long study of radioactivity. – Marie Curie wrote, "The subject seemed to us very attractive and all the Marie Curie wrote, "The subject seemed to us very attractive and all the

more so because the question was entirely new and nothing yet had been more so because the question was entirely new and nothing yet had been written upon it." written upon it."

Becquerel had already noted that uranium emanations could turn air Becquerel had already noted that uranium emanations could turn air into a conductor of electricity. into a conductor of electricity. – Using sensitive instruments invented by Pierre Curie and his brother, Pierre Using sensitive instruments invented by Pierre Curie and his brother, Pierre

and Marie Curie measured the ability of emanations from various elements and Marie Curie measured the ability of emanations from various elements to induce conductivity. to induce conductivity.

– On February 17, 1898, the Curies tested an ore of uranium, pitchblende, for On February 17, 1898, the Curies tested an ore of uranium, pitchblende, for its ability to turn air into a conductor of electricity.its ability to turn air into a conductor of electricity.

– The Curies found that the pitchblende produced a current 300 times The Curies found that the pitchblende produced a current 300 times stronger than that produced by pure uranium. stronger than that produced by pure uranium.

– They tested and recalibrated their instruments, and yet they still found the They tested and recalibrated their instruments, and yet they still found the same puzzling results. same puzzling results.

– The Curies reasoned that a very active unknown substance in addition to The Curies reasoned that a very active unknown substance in addition to the uranium must exist within the pitchblende. the uranium must exist within the pitchblende.

– In the title of a paper describing this hypothesized element (which they In the title of a paper describing this hypothesized element (which they named polonium after Marie's native Poland), they introduced the new named polonium after Marie's native Poland), they introduced the new term: "radio-active." term: "radio-active."

The Curies: Lives Devoted The Curies: Lives Devoted to Research (Cont)to Research (Cont)

After much grueling work, the Curies were able to extract After much grueling work, the Curies were able to extract enough polonium and another radioactive element, radium, enough polonium and another radioactive element, radium, to establish the chemical properties of these elements. to establish the chemical properties of these elements.

Marie Curie, with her husband and continuing after his Marie Curie, with her husband and continuing after his death, established the first quantitative standards by which death, established the first quantitative standards by which the rate of radioactive emission of charged particles from the rate of radioactive emission of charged particles from elements could be measured and compared. elements could be measured and compared.

In addition, she found that there was a decrease in the rate In addition, she found that there was a decrease in the rate of radioactive emissions over time and that this decrease of radioactive emissions over time and that this decrease could be calculated and predicted. could be calculated and predicted.

But perhaps Marie Curie's greatest and most unique But perhaps Marie Curie's greatest and most unique achievement was her realization that achievement was her realization that radiation is an radiation is an atomic property of matter rather than a separate atomic property of matter rather than a separate independent emanationindependent emanation. .

Despite the giant step forward which science had now Despite the giant step forward which science had now taken in it's understanding of radioactivity, scientists still taken in it's understanding of radioactivity, scientists still understood little of the structure of the atom.understood little of the structure of the atom.

Radiation: Basic DefinitionsRadiation: Basic Definitions Radioactive materials are composed of atoms that Radioactive materials are composed of atoms that

are unstable.  An unstable atom gives off excess are unstable.  An unstable atom gives off excess energy until it becomes stable.  The energy the atom energy until it becomes stable.  The energy the atom emits is emits is radiationradiation.  The process by which an atom .  The process by which an atom changes from an unstable state to a more stable changes from an unstable state to a more stable state by emitting radiation is called state by emitting radiation is called radioactivityradioactivity.  . 

Radiation can be classified as either non-ionizing (low Radiation can be classified as either non-ionizing (low energy) or ionizing (high energy) radiation.  Types of energy) or ionizing (high energy) radiation.  Types of non-ionizing radiationnon-ionizing radiation are ultraviolet light, visible are ultraviolet light, visible light, infrared radiation, radio frequency radiation light, infrared radiation, radio frequency radiation and microwaves.  and microwaves.  Ionizing radiationIonizing radiation  is given off by   is given off by the sun (cosmic rays), radioactive materials, and the sun (cosmic rays), radioactive materials, and high energy electronic devices (X-ray machines).  high energy electronic devices (X-ray machines).  

4 Types of Ionizing 4 Types of Ionizing RadiationRadiation

Alpha (Alpha () particles) particles– 2 protons, 2 neutrons (He)2 protons, 2 neutrons (He)

Beta (Beta () particles) particles– 1 electron1 electron

Gamma (Gamma ()particles)particles– 1 photon1 photon

X-raysX-rays– 1 photon1 photon

N.B. N.B. and X-ray photons are different and X-ray photons are different types of electromagnetic radiation and types of electromagnetic radiation and have different energy levelshave different energy levels

Alpha ParticlesAlpha Particles

Positively charged particles made up Positively charged particles made up of two neutrons and two protons.  of two neutrons and two protons. 

They are relatively heavy and slower They are relatively heavy and slower moving than other radioactive moving than other radioactive emissions.  emissions. 

Alpha particles can be stopped  by a Alpha particles can be stopped  by a piece of paper or the dead outer layer piece of paper or the dead outer layer of our skin. of our skin.

Alpha particles are dangerous when Alpha particles are dangerous when ingested or inhaled.ingested or inhaled.

Beta ParticlesBeta Particles

Negatively charged particles made Negatively charged particles made up of an electron.  up of an electron. 

A beta particle is lighter and faster A beta particle is lighter and faster than an alpha particle.than an alpha particle.

Beta radiation can pass through an Beta radiation can pass through an inch of water or skin, but not through inch of water or skin, but not through a thin sheet of aluminum, plywood or a thin sheet of aluminum, plywood or steel. steel.

Gamma RadiationGamma Radiation

Short wavelength electromagnetic Short wavelength electromagnetic radiation emitted in the radioactive radiation emitted in the radioactive decay of an unstable atom.   decay of an unstable atom.  

Gamma radiation is highly penetrating Gamma radiation is highly penetrating but carries no mass or charge.but carries no mass or charge.

Stopping gamma rays requires one Stopping gamma rays requires one inch of a dense material like lead or inch of a dense material like lead or concrete.   concrete.  

X-raysX-rays

X-rays X-rays are similar to gamma rays, are similar to gamma rays, but are generally lower in energy and but are generally lower in energy and less penetrating.  less penetrating. 

X-rays are emitted from processes X-rays are emitted from processes outside the nucleus, while gamma outside the nucleus, while gamma rays originate inside the nucleus.    rays originate inside the nucleus.   

A few milimeters of lead can stop A few milimeters of lead can stop medical x-rays.  medical x-rays. 

Sources of RadiationSources of Radiation

The Penetrating Power of The Penetrating Power of RadiationRadiation

AtomsAtoms Atomic Nuclei are held together by the Atomic Nuclei are held together by the

“strong nuclear force”“strong nuclear force” one of four one of four forces in the universe.forces in the universe.– GravityGravity is also one of these four forces. is also one of these four forces. – It is the weakest.It is the weakest.

The positively charged The positively charged protonsprotons also repel also repel each other by electromagnetism.each other by electromagnetism.– Remember, when an electrically charged Remember, when an electrically charged

particle moves, it creates a magnetic field.particle moves, it creates a magnetic field. The The neutronsneutrons provide a buffer between provide a buffer between

the positive charges in the nucleus.the positive charges in the nucleus.– Remember, neutrons have no net charge. Remember, neutrons have no net charge.

Atoms (Cont)Atoms (Cont) The larger the nucleus, the larger both types of The larger the nucleus, the larger both types of

forces, strong and electromagnetic.forces, strong and electromagnetic. When the electromagnetic force is greater than When the electromagnetic force is greater than

the strong force, the nucleus will the strong force, the nucleus will decaydecay..– To balance the forces, the ratio of neutrons:protons To balance the forces, the ratio of neutrons:protons

must be ~1:1 for atoms with <20 protons, and ~1.5:1 must be ~1:1 for atoms with <20 protons, and ~1.5:1 for the largest atoms.for the largest atoms.

– Ratios both above and below this range result in Ratios both above and below this range result in radioactive isotopes.radioactive isotopes.

RadioactivityRadioactivity: During decay, matter and energy : During decay, matter and energy are expelled from the nucleus, making it are expelled from the nucleus, making it unstableunstable. Decay continues until stability has . Decay continues until stability has been reached within the nucleus.been reached within the nucleus.

Alpha, Beta, and Gamma Alpha, Beta, and Gamma DecayDecay

Beta decay occurs when the n:p ratio is above the Beta decay occurs when the n:p ratio is above the stability curve, as it reduces the # of neutrons in stability curve, as it reduces the # of neutrons in the nucleusthe nucleus

All elements with 83 protons or greater are All elements with 83 protons or greater are radioactive and undergo alpha decay.radioactive and undergo alpha decay.– Alpha decay reduces both the number of neutrons and Alpha decay reduces both the number of neutrons and

protons in the nucleus, helping to stabilize these very protons in the nucleus, helping to stabilize these very large nuclei.large nuclei.

Gamma decay tends to occur in both scenarios, Gamma decay tends to occur in both scenarios, but doesn’t affect mass or charge, and is therefore but doesn’t affect mass or charge, and is therefore usually omitted when balancing the equation.usually omitted when balancing the equation.

Some isotopes of an element are stable, others Some isotopes of an element are stable, others are radioactive.are radioactive.

Positron Emission and Electron Positron Emission and Electron CaptureCapture

A positron has the same mass as an A positron has the same mass as an electron, but opposite chargeelectron, but opposite charge– When the n:p ratio lies below the stability When the n:p ratio lies below the stability

curve, a positron may be emitted to convert a curve, a positron may be emitted to convert a proton into a neutronproton into a neutron

During electron capture, an electron from During electron capture, an electron from a low-energy orbital is combined with a a low-energy orbital is combined with a proton to form a neutronproton to form a neutron– This also occurs when the n:p ratio lies below This also occurs when the n:p ratio lies below

the stability curvethe stability curve– An X-ray photon is emitted during electron An X-ray photon is emitted during electron

capturecapture

TransmutationTransmutation

When the atomic number of an atom When the atomic number of an atom changes, its elemental identity changes, its elemental identity changeschanges

All forms of radiation except All forms of radiation except and X- and X-ray radiation cause transmutation to ray radiation cause transmutation to occurs.occurs.

Reading the Periodic TableReading the Periodic Table

Element symbols: Element symbols:

CCTop number is atomic mass, lower number is atomic Top number is atomic mass, lower number is atomic

number.number.

Atomic massAtomic mass is the total number of protons and is the total number of protons and neutrons in the nucleus.neutrons in the nucleus.

Atomic numberAtomic number is the total number of protons in the is the total number of protons in the nucleus.nucleus.

6

12

Calculating Atomic ParticlesCalculating Atomic Particles

Carbon-14 is radioactive Carbon-14 is radioactive

CCHow many neutrons does carbon-14 have?How many neutrons does carbon-14 have?

6

14

Balancing Nuclear EquationsBalancing Nuclear Equations

Oxygen-15 undergoes positron Oxygen-15 undergoes positron emission. Show the balanced emission. Show the balanced equation.equation.

Reactant: Reactant: 1515O O

88

Product: Product: 1515N + N + 00

77

11

Balancing Nuclear EquationsBalancing Nuclear Equations

Thorium-231 becomes Protactinium-Thorium-231 becomes Protactinium-231. Show the balanced equation and 231. Show the balanced equation and identify the type of radioactive decay.identify the type of radioactive decay.

Reactant: Reactant: 231231ThTh

9090

Product: Product: 231231Pa + Pa + 00

9191 -1 -1

Radioactive DatingRadioactive Dating

Half-lifeHalf-life: the time necessary for : the time necessary for 50% of the element to decay.50% of the element to decay.

The age of an item can be The age of an item can be determined by comparing the determined by comparing the original amount of radioactive original amount of radioactive material with the current amount.material with the current amount.– Amt Remaining=Initial Amt (1/2)Amt Remaining=Initial Amt (1/2)t/Tt/T

– t=time elapsed, T=period of one half-lifet=time elapsed, T=period of one half-life

Radioactive Decay—the Real Radioactive Decay—the Real EquationEquation

A common example of exponential decay is A common example of exponential decay is radioactive decayradioactive decay. Radioactive materials, . Radioactive materials, and some other substances, decompose and some other substances, decompose according to a formula for exponential according to a formula for exponential decay. decay. That is, the amount of radioactive material That is, the amount of radioactive material A present at time t is given by the formula A present at time t is given by the formula

A=AA=A00eektkt

where k < 0. where k < 0. A radioactive substance is often described A radioactive substance is often described

in terms of its in terms of its half-lifehalf-life, which is the time , which is the time required for half the material to decompose. required for half the material to decompose.

ProblemProblem

After 500 years, a sample of radium-After 500 years, a sample of radium-226 has decayed to 80.4% of its 226 has decayed to 80.4% of its original mass. Find the half-life of original mass. Find the half-life of radium-226. radium-226.

SolutionSolution Let A= the mass of radium present at time t (t=0 Let A= the mass of radium present at time t (t=0

corresponds to 500 years ago). We want to know for what corresponds to 500 years ago). We want to know for what time t is A = (1/2)Atime t is A = (1/2)A00. However, we do not even know what k . However, we do not even know what k is yet. Once we know what k is, we can set A in the formula is yet. Once we know what k is, we can set A in the formula for exponential decay to be equal to (1/2) Afor exponential decay to be equal to (1/2) A00, and then , and then solve for t. First we must determine k. We are given that solve for t. First we must determine k. We are given that after 500 years, the amount present is 80.4% of its original after 500 years, the amount present is 80.4% of its original mass. That is, when t=500, A=0.804 Amass. That is, when t=500, A=0.804 A00. Substituting these . Substituting these values into the formula for exponential decay, we obtain: values into the formula for exponential decay, we obtain:

0.804 A0.804 A00=A=A00eek(500)k(500)..

Dividing through by ADividing through by A00 gives us gives us 0.804 = e0.804 = e500k500k

which is an exponential equation. which is an exponential equation.

Solving the EquationSolving the Equation To solve this equation, we take natural logs (ie. ln) of both To solve this equation, we take natural logs (ie. ln) of both

sides. sides. ln ( 0.804) = ln (eln ( 0.804) = ln (e500k500k) )

We know that ln (eWe know that ln (e500k500k) = 500k by the cancellation properties ) = 500k by the cancellation properties of ln and e. So the equation becomes of ln and e. So the equation becomes

ln ( 0.804) = 500kln ( 0.804) = 500k

and and k= (ln 0.804)/500. k= (ln 0.804)/500.

This is the exact solution; evaluate the natural log with a This is the exact solution; evaluate the natural log with a calculator to get the decimal approximation k = -0.000436 . calculator to get the decimal approximation k = -0.000436 . Since we now know k, we can write the formula (function) for Since we now know k, we can write the formula (function) for the amount of radium present at time t as the amount of radium present at time t as

A=AA=A00 e e-0.000436 t-0.000436 t..

Finding the half-lifeFinding the half-life Now, we can finally find the half-life. We set A=1/2 ANow, we can finally find the half-life. We set A=1/2 A00 and solve and solve

for t. for t. (1/2)A(1/2)A00=A=A00 e e-0.000436 t-0.000436 t

Dividing through by ADividing through by A00 again, we get: again, we get: 1/2 = e1/2 = e-0.000436 t.-0.000436 t.

To solve for t, take natural logs: To solve for t, take natural logs:

ln(1/2) = ln[eln(1/2) = ln[e-0.000436 t-0.000436 t]. ].

Then applying the cancellation property for logarithms yields Then applying the cancellation property for logarithms yields ln (1/2) = -0.000436 tln (1/2) = -0.000436 t

So So t= ln(1/2) /(-0.000436)t= ln(1/2) /(-0.000436)

or t = 1590. The half-life is approximately 1590 years. or t = 1590. The half-life is approximately 1590 years.

Carbon DatingCarbon Dating The dating of radioactive carbon has helped to The dating of radioactive carbon has helped to

define the history of life on this planet. define the history of life on this planet. – Any living organism takes in both radioactive and non-Any living organism takes in both radioactive and non-

radioactive carbon, either through the process of radioactive carbon, either through the process of photosynthesis or by eating plants or eating animals photosynthesis or by eating plants or eating animals that have eaten plants. that have eaten plants.

– When the animal dies, however, uptake of carbon stops. When the animal dies, however, uptake of carbon stops. – As a result, radioactive carbon atoms are not replaced As a result, radioactive carbon atoms are not replaced

as they decay, and the amount of this material as they decay, and the amount of this material decreases over time. decreases over time.

– The rate of decrease is predictable and can be The rate of decrease is predictable and can be described with accuracy, vastly increasing our ability to described with accuracy, vastly increasing our ability to date the biological events of our planet.date the biological events of our planet.

Example: Carbon DatingExample: Carbon Dating

The half-life of carbon-14 =5,730 The half-life of carbon-14 =5,730 years.years.

If an organism had 100 If an organism had 100 1414C atoms C atoms during its life, then, in 5,730 years, it during its life, then, in 5,730 years, it will have 50.will have 50.

Carbon dating is used to date organic Carbon dating is used to date organic samples less than 50,000 years old.samples less than 50,000 years old.

Other Radioactive DatingOther Radioactive Dating

Uranium: 4,040,000 yearsUranium: 4,040,000 years

Iodine: 8.04 daysIodine: 8.04 days

Lead 10.6 hoursLead 10.6 hours

Applications: Isotopes in Applications: Isotopes in Research and MedicineResearch and Medicine

Scientists can now create radioactive forms of Scientists can now create radioactive forms of common elements, called common elements, called isotopesisotopes. . – Each isotope has a fixed rate of decay which can be Each isotope has a fixed rate of decay which can be

characterized by its characterized by its half-lifehalf-life, or the length of time , or the length of time that it takes half of the radioactive atoms in a sample that it takes half of the radioactive atoms in a sample to decay. to decay.

– Because each isotope decays at a unique and Because each isotope decays at a unique and predictable rate, different isotopes can be used for a predictable rate, different isotopes can be used for a variety of purposes. variety of purposes.

– For example, isotopes play an important role in For example, isotopes play an important role in modern medicine. modern medicine. They can be ingested and traced in their path through the They can be ingested and traced in their path through the

body, revealing biochemical and metabolic processes with body, revealing biochemical and metabolic processes with precision. precision.

These isotropic "tracers" are currently used for practical These isotropic "tracers" are currently used for practical diagnosis of disease as well as in research. diagnosis of disease as well as in research.

Other Uses Other Uses

PET Scans:PET Scans: Radioactive Fluorine is Radioactive Fluorine is injected into the bloodstream, injected into the bloodstream, allowing doctors to view brain allowing doctors to view brain activity.activity.

Radiation therapyRadiation therapy: Radiation is : Radiation is targeted to a specific tumor to kill targeted to a specific tumor to kill those cells. those cells.

Used to trace chemical reactions.Used to trace chemical reactions.

Damage from RadiationDamage from Radiation All forms of radiation can damage a DNA molecule.All forms of radiation can damage a DNA molecule.

– E.g. UV causes lesions in the DNAE.g. UV causes lesions in the DNA– E.g. E.g. causes double-strand breaks in the DNA causes double-strand breaks in the DNA– Any time structural change occurs in the DNA, it has to be Any time structural change occurs in the DNA, it has to be

repaired. If it is not repaired correctly, mutation occurs.repaired. If it is not repaired correctly, mutation occurs. When damage occurs to an important gene, cancer can When damage occurs to an important gene, cancer can

result.result. What is an important gene?What is an important gene?

– Any gene encoding a protein involved in regulating the cell cycle, Any gene encoding a protein involved in regulating the cell cycle, DNA replication, or DNA repair.DNA replication, or DNA repair.

– Defects in these genes lead to accumulations of mutations, loss Defects in these genes lead to accumulations of mutations, loss of apoptosis and cell death in ineffective cells, and cancer arises of apoptosis and cell death in ineffective cells, and cancer arises because these non-functioning “tumor” cells out-divide because these non-functioning “tumor” cells out-divide functioning cells in the body.functioning cells in the body.

EmbryosEmbryos

If the DNA of an embryo is damaged, If the DNA of an embryo is damaged, birth defects, rather than cancer can birth defects, rather than cancer can result.result.– In fact, researchers study embryonic In fact, researchers study embryonic

and fetal development in the hopes of and fetal development in the hopes of understanding the roots of cancer, as understanding the roots of cancer, as cancer is almost the “reverse” or cancer is almost the “reverse” or “second-coming” of normal “second-coming” of normal development.development.

Specific Uses of Certain Specific Uses of Certain ElementsElements Americium -241:Americium -241: Used in many smoke detectors for homes and Used in many smoke detectors for homes and

business...to measure levels of toxic lead in dried paint samples...to business...to measure levels of toxic lead in dried paint samples...to ensure uniform thickness in rolling processes like steel and paper ensure uniform thickness in rolling processes like steel and paper production...and to help determine where oil wells should be drilled. production...and to help determine where oil wells should be drilled.

Cadmium -109:Cadmium -109: Used to analyze metal alloys for checking stock, Used to analyze metal alloys for checking stock, sorting scrap. sorting scrap.

Calcium - 47:Calcium - 47: Important aid to biomedical researchers studying the Important aid to biomedical researchers studying the cell function and bone formation of mammals. cell function and bone formation of mammals.

Californium - 252:Californium - 252: Used to inspect airline luggage for hidden Used to inspect airline luggage for hidden explosives...to gauge the moisture content of soil in the road explosives...to gauge the moisture content of soil in the road construction and building industries...and to measure the moisture of construction and building industries...and to measure the moisture of materials stored in silos. materials stored in silos.

Carbon - 14:Carbon - 14: Helps in research to ensure that potential new drugs Helps in research to ensure that potential new drugs are metabolized without forming harmful by-products. are metabolized without forming harmful by-products.

Cesium - 137:Cesium - 137: Used to treat cancers...to measure correct patient Used to treat cancers...to measure correct patient dosages of radioactive pharmaceuticals...to measure and control the dosages of radioactive pharmaceuticals...to measure and control the liquid flow in oil pipelines...to tell researchers whether oil wells are liquid flow in oil pipelines...to tell researchers whether oil wells are plugged by sand...and to ensure the right fill level for packages of plugged by sand...and to ensure the right fill level for packages of food, drugs and other products. (The products in these packages do food, drugs and other products. (The products in these packages do not become radioactive.) not become radioactive.)

Chromium - 51:Chromium - 51: Used in research in red blood cell survival studies. Used in research in red blood cell survival studies.

Specific Uses of Certain Specific Uses of Certain Elements (Cont)Elements (Cont)

Cobalt - 57:Cobalt - 57: Used in nuclear medicine to help physicians interpret Used in nuclear medicine to help physicians interpret diagnosis scans of patients' organs, and to diagnose pernicious diagnosis scans of patients' organs, and to diagnose pernicious anemia. anemia.

Cobalt - 60 :Cobalt - 60 : Used to sterilize surgical instruments...to improve the Used to sterilize surgical instruments...to improve the safety and reliability of industrial fuel oil burners...and to preserve safety and reliability of industrial fuel oil burners...and to preserve poultry, fruits, and spices. poultry, fruits, and spices.

Copper - 67:Copper - 67: When injected with monoclonal antibodies into a When injected with monoclonal antibodies into a cancer patient, helps the antibodies bind to and destroy the tumor. cancer patient, helps the antibodies bind to and destroy the tumor.

Curium - 244:Curium - 244: Used in mining to analyze material excavated from Used in mining to analyze material excavated from pits slurries from drilling operations. pits slurries from drilling operations.

Iodine - 123:Iodine - 123: Widely used to diagnose thyroid disorders. Widely used to diagnose thyroid disorders. Iodine - 129:Iodine - 129: Used to check some radioactivity counters in vitro Used to check some radioactivity counters in vitro

diagnostic testing laboratories. diagnostic testing laboratories. Iodine - 131:Iodine - 131: Used to diagnose and treat thyroid disorders. Used to diagnose and treat thyroid disorders.

(Former President George Bush and Mrs. Bush were both (Former President George Bush and Mrs. Bush were both successfully treated for Grave's disease, a thyroid disease, with successfully treated for Grave's disease, a thyroid disease, with radioactive iodine.) radioactive iodine.)

Iridium - 192:Iridium - 192: Used to test the integrity of pipeline welds, boilers Used to test the integrity of pipeline welds, boilers and aircraft parts. and aircraft parts.

Iron - 55:Iron - 55: Used to analyze electroplating solutions. Used to analyze electroplating solutions.

Specific Uses of Certain Specific Uses of Certain Elements (Cont)Elements (Cont)

Krypton - 85:Krypton - 85: Used in indicator lights in appliances like clothes washer Used in indicator lights in appliances like clothes washer and dryers, stereos and coffee makers...to gauge the thickness of thin and dryers, stereos and coffee makers...to gauge the thickness of thin plastics and sheet metal, rubber, textiles and paper...and to measure dust plastics and sheet metal, rubber, textiles and paper...and to measure dust and pollutant levels. and pollutant levels.

Nickel - 63:Nickel - 63: Used to detect explosives...and as voltage regulators and Used to detect explosives...and as voltage regulators and current surge protectors in electronic devices. current surge protectors in electronic devices.

Phosphorus - 32:Phosphorus - 32: Used in molecular biology and genetics research. Used in molecular biology and genetics research. Plutonium - 238:Plutonium - 238: Has safely powered at least 20 NASA spacecraft since Has safely powered at least 20 NASA spacecraft since

1972. 1972. Polonium - 210:Polonium - 210: Reduces the static charge in production of photographic Reduces the static charge in production of photographic

film and phonograph records. film and phonograph records. Promethium - 147:Promethium - 147: Used in electric blanket thermostats...and to gauge Used in electric blanket thermostats...and to gauge

the thickness of thin plastics, thin sheet metal, rubber, textiles, and paper. the thickness of thin plastics, thin sheet metal, rubber, textiles, and paper. Radium - 226:Radium - 226: Makes lightning rods more effective. Makes lightning rods more effective. Selenium - 75:Selenium - 75: Used in protein studies in life science research. Used in protein studies in life science research. Sodium - 24:Sodium - 24: Used to locate leaks in industrial pipelines...and in oil well Used to locate leaks in industrial pipelines...and in oil well

studies. studies. Strontium - 85:Strontium - 85: Used to study bone formation and metabolism. Used to study bone formation and metabolism. Technetium - 99m:Technetium - 99m: The most widely used radioactive isotope for The most widely used radioactive isotope for

diagnostic studies in nuclear medicine. Different chemical forms are used diagnostic studies in nuclear medicine. Different chemical forms are used for brain, bone, liver, spleen and kidney imaging and also for blood flow for brain, bone, liver, spleen and kidney imaging and also for blood flow studies.studies.

Specific Uses of Certain Specific Uses of Certain Elements (Cont)Elements (Cont)

Thallium - 204:Thallium - 204: Measures the dust and pollutant levels on filter Measures the dust and pollutant levels on filter paper...and gauges the thickness of plastics, sheet metal, rubber, paper...and gauges the thickness of plastics, sheet metal, rubber, textiles and paper. textiles and paper.

Thoriated tungsten:Thoriated tungsten: Used in electric are welding rods in the Used in electric are welding rods in the construction, aircraft, petrochemical and food processing equipment construction, aircraft, petrochemical and food processing equipment industries. It produces easier starting, greater arc stability and less industries. It produces easier starting, greater arc stability and less metal contamination. metal contamination.

Thorium - 229:Thorium - 229: Helps fluorescent lights to last longer. Helps fluorescent lights to last longer. Thorium - 230:Thorium - 230: Provides coloring and fluorescence in colored glazes Provides coloring and fluorescence in colored glazes

and glassware. and glassware. Tritium:Tritium: Used for life science and drug metabolism studies to ensure Used for life science and drug metabolism studies to ensure

the safety of potential new drugs... for self-luminous aircraft and the safety of potential new drugs... for self-luminous aircraft and commercial exit signs... for luminous dials, gauges and wrist commercial exit signs... for luminous dials, gauges and wrist watches...and to produce luminous paint. watches...and to produce luminous paint.

Uranium - 234:Uranium - 234: Used in dental fixtures like crowns and dentures to Used in dental fixtures like crowns and dentures to provide a natural color and brightness. provide a natural color and brightness.

Uranium - 235:Uranium - 235: Fuel for nuclear power plants and naval nuclear Fuel for nuclear power plants and naval nuclear propulsion systems...also used to produce fluorescent glassware, a propulsion systems...also used to produce fluorescent glassware, a variety of colored glazes and wall tiles. variety of colored glazes and wall tiles.

Xenon - 133:Xenon - 133: Used in nuclear medicine for lung ventilation and blood Used in nuclear medicine for lung ventilation and blood flow studies.flow studies.