NAME: COOKEY-GAM TAMUNO-OPUBO
Radioactivity is the decay or disintegration of the nucleus of a
radioactive element. The radiation emitted is; the alpha-particles, the
beta-particles and the gamma rays and a lot of heat. This
phenomenon was first discovered by a French Physicist, Henri
Becquerel in 1896. Other famous people parts of this radioactive era
are; Lord Rutherford, and the Curie couple, Marie and Pierre.
In March of 1896, during a time of overcast weather, Becquerel found he couldn't use the
sun as an initiating energy source for his experiments. He put his wrapped photographic
plates away in a darkened drawer, along with some crystals containing uranium. Much to
his Becquerel's surprise, the plates were exposed during storage by invisible emanations
from the uranium. The emanations did not require the presence of an initiating energy
source--the crystals emitted rays on their own! Although Becquerel did not pursue his
discovery of radioactivity, others did and, in so doing, changed the face of both modern
medicine and modern science. He was a member of a scientific family extending through
several generations, the most notable being his grandfather Antoine-César Becquerel
(1788–1878), his father, Alexandre-Edmond Becquerel (1820–91), and his son Jean
THE CURIES’ DISCOVERY:
Working in the Becquerel lab, Marie Curie and her husband, Pierre, began what became a
life long study of radioactivity. It took fresh and open minds, along with much dedicated
work, for these scientists to establish the properties of radioactive matter. 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 written upon it." On February 17, 1898, the
Curies tested an ore of uranium, pitchblende, for its ability to turn air into a conductor of
electricity. The Curies found that the pitchblende produced a current 300 times stronger
than that produced by pure uranium. They tested and recalibrated their instruments, and
yet they still found the same puzzling results. The Curies reasoned that a very active
unknown substance in addition to the uranium must exist within the pitchblende. In the
title of a paper describing this hypothesized element (which they named polonium after
Marie's native Poland), they introduced the new term: "radio-active."
After much grueling work, the Curies were able to extract enough polonium and another
radioactive element, radium, to establish the chemical properties of these elements. Marie
Curie, with her husband and continuing after his death, established the first quantitative
standards by which the rate of radioactive emission of charged particles from elements
could be measured and compared. In addition, she found that there was a decrease in the
rate of radioactive emissions over time and that this decrease could be calculated and
predicted. But perhaps Marie Curie's greatest and most unique achievement was her
realization that radiation is an atomic property of matter rather than a separate
independent emanation. Polish-born French physicist, famous for her work on
radioactivity and twice a winner of the Nobel Prize. With Henri Becquerel and her
husband, Pierre Curie, she was awarded the 1903 Nobel Prize for Physics. She was the
sole winner of the 1911 Nobel Prize for Chemistry. She was the first woman to win a
Nobel Prize, and she is the only woman to win the award in two different fields.
In 1911, Rutherford conducted a series of experiments in which he bombarded a piece of
gold foil with positively charged (alpha) particles emitted by radioactive material. Most
of the particles passed through the foil undisturbed, suggesting that the foil was made up
mostly of empty space rather than of a sheet of solid atoms. Some alpha particles,
however, "bounced back," indicating the presence of solid matter. Atomic particles,
Rutherford's work showed, consisted primarily of empty space surrounding a well-
defined central core called a nucleus.
In a long and distinguished career, Rutherford laid the groundwork for the determination
of atomic structure. In addition to defining the planetary model of the atom, he showed
that radioactive elements undergo a process of decay over time. And, in experiments
which involved what newspapers of his day called "splitting the atom," Rutherford was
the first to artificially transmute one element into another--unleashing the incredible
power of the atom which would eventually be harnessed for both beneficial and
Taken together, the work of Becquerel, the Curies,
Rutherford and others, made modern medical and
scientific research more than a dream. They made it a
reality with many applications. A look at the use of
isotopes reveals just some of the ways in which the
pioneering work of these scientists has been utilized.
1. Alpha-particles: This type of radiation is positively
charged. It is relatively massive. It has a low penetrating
power. It’s about 1-20th as fast as light. It is exactly like the
2. Beta-particles: This type of radiation is negatively
charged(but can also be +vely charged). It is relatively
light. It is about as fast as light. They are high energy
electrons. It has a medium penetrating power.
3. Gamma Rays: This radiation is neutral in charge. Has a
very high penetrating power. It is at the speed of light. It is
an electromagnetic wave with very short wavelength. It is
TYPES OF RADIOACTIVITY
1. NATURAL RADIOACTIVITY
2. ARTIFICIAL RADIOACTRIVITY
1 NATURAL RADIOACTIVITY
This is the type of radioactivity which consists of a spontaneous
decay of the radioactive nucleus. The phenomenon is experienced by
naturally radioactive substances. The radiation might come out
individually or combined and, as always, with a lot of energy.
Some radioactive substances are:
Americium -241: Used in many smoke detectors for homes and business...to measure
levels of toxic lead in dried paint samples...to ensure uniform thickness in rolling
processes like steel and paper production...and to help determine where oil wells should
Cadmium -109: Used to analyze metal alloys for checking stock, sorting scrap.
Calcium - 47: Important aid to biomedical researchers studying the cell function and
bone formation of mammals.
Californium - 252: Used to inspect airline luggage for hidden explosives...to gauge the
moisture content of soil in the road construction and building industries...and to measure
the moisture of materials stored in silos.
Carbon - 14: Helps in research to ensure that potential new drugs are metabolized
without forming harmful by-products.
Cesium - 137: Used to treat cancers...to measure correct patient dosages of radioactive
pharmaceuticals...to measure and control the 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 food, drugs and other products. (The products in these packages do not
Chromium - 51: Used in research in red blood cell survival studies.
Cobalt - 57: Used in nuclear medicine to help physicians interpret diagnosis scans of
patients' organs, and to diagnose pernicious anemia.
Cobalt - 60 : Used to sterilize surgical instruments...to improve the safety and reliability
of industrial fuel oil burners...and to preserve poultry fruits and spices.
Copper - 67: When injected with monoclonal antibodies into a cancer patient, helps the
antibodies bind to and destroy the tumor.
Curium - 244: Used in mining to analyze material excavated from pits slurries from
Iodine - 123: Widely used to diagnose thyroid disorders.
Iodine - 129: Used to check some radioactivity counters in vitro diagnostic testing
Iodine - 131: Used to diagnose and treat thyroid disorders. (Former President George
Bush and Mrs. Bush were both successfully treated for Grave's disease, a thyroid disease,
with radioactive iodine.)
Iridium - 192: Used to test the integrity of pipeline welds, boilers and aircraft parts.
Iron - 55: Used to analyze electroplating solutions.
Krypton - 85: Used in indicator lights in appliances like clothes washer and dryers,
stereos and coffee makers...to gauge the thickness of thin plastics and sheet metal, rubber,
textiles and paper...and to measure dust and pollutant levels.
Nickel - 63: Used to detect explosives...and as voltage regulators and current surge
protectors in electronic devices.
Phosphorus - 32: Used in molecular biology and genetics research.
Plutonium - 238: Has safely powered at least 20 NASA spacecraft since 1972.
Polonium - 210: Reduces the static charge in production of photographic film and
Promethium - 147: Used in electric blanket thermostats...and to gauge the thickness of
thin plastics, thin sheet metal, rubber, textiles, and paper.
Radium - 226: Makes lightning rods more effective.
Selenium - 75: Used in protein studies in life science research.
Sodium - 24: Used to locate leaks in industrial pipelines...and in oil well studies.
Strontium - 85: Used to study bone formation and metabolism.
Technetium - 99m: The most widely used radioactive isotope for diagnostic studies in
nuclear medicine. Different chemical forms are used for brain, bone, liver, spleen and
kidney imaging and also for blood flow studies.
Thallium - 204: Measures the dust and pollutant levels on filter paper...and gauges the
thickness of plastics, sheet metal, rubber, textiles and paper.
Thoriated tungsten: Used in electric are welding rods in the construction, aircraft,
petrochemical and food processing equipment industries. It produces easier starting,
greater arc stability and less metal contamination.
Thorium - 229: Helps fluorescent lights to last longer.
Thorium - 230: Provides coloring and fluorescence in colored glazes and glassware.
Tritium: Used for life science and drug metabolism studies to ensure the safety of
potential new drugs... for self-luminous aircraft and commercial exit signs... for luminous
dials, gauges and wrist watches...and to produce luminous paint.
Uranium - 234: Used in dental fixtures like crowns and dentures to provide a natural
color and brightness.
Uranium - 235: Fuel for nuclear power plants and naval nuclear propulsion
systems...also used to produce fluorescent glassware, a variety of colored glazes and wall
Xenon - 133: Used in nuclear medicine for lung ventilation and blood flow studies.
2 ARTIFICIAL RADIOACTIVITY
In this radioactivity, normally unreactive elements are made
reactive by bombarding them with radiation. E.g. bombarding
aluminium with alpha particles, producing a radioactive
phosphorous which decays to silicon. Nitrogen-14 is made
reactive by bombarding it with cosmic rays.
This is the creation of ions by loss or gain of electrons producing
cations or anions respectively. Radiation usually forms cations
this is because the emitted rays have such high energy that they
knock out the valence electrons of the elements.
DETECTION OF RADIATION.
1. USING A DOSIMETER OR A FILM BADGE: A dosimeter
is a device worn by radioactive workers. It is basically a film
which darkens on incidence of radiation. It is used to know the
level of radiation the worker has
been exposed t
2. A GEIGER COUNTER: This consists of a Geiger-Muller
tube (which consists of a wire), a scaler/ratemeter, and often a
loudspeaker. The walls of the container acts as the cathode while
the central wire acts as the anode. The radiation enters through a
thin window. Each particle or ray ionizes several gas atoms. Ions
attracted to the cathode, electrons to the anode. Other atoms are hit
on the way creating an avalanche of more ions and electrons. The
loudspeaker amplifies a click sound for each pulse showing the
randomness of the decay.
3. Pulse (Wulf Electroscope)
4. Cloud Chamber
5. Bubble Chamber
6. Scintillation Counter (for detecting gamma rays)
USES OF RADIOACTIVITY
1. Radiology: This is used for research and study in the medical
2. Radiotherapy: This is used in the treatment of diseases,
especially cancer. Due to the penetrating power of gamma rays,
they are used to collectively and controllably destroy malignant
3. Irradiation: This is the exposure of controlled gamma rays to
fruits or vegetables to delay ripening and improve freshness
length of the irradiated foodstuffs.
4. Gamma-Radiography: This is the production of a special type of
photograph, a radiograph. It is used for quality control in
industries. The making of a radiograph requires some type of recording
mechanism. The most common device is film. A radiograph is actually a
photographic recording produced by the passage of radiation through a
subject onto a film, producing what is called a latent image of the subject.
A latent image is an image that has been created on the film due to the
interaction of radiation with the material making up the film. This latent
image is not visible to the naked eye until further processing has taken
place. To make the latent image visible the film is processed by exposure to
chemicals similar to that of photographic film.
5. Radiocarbon or carbon dating: All living matter contains
carbon-14 absorbed from the atmosphere. This radioactive element
has a half-life of about 5300 years. The element continues
decaying even after death of the living organism. This phenomenon
is used to estimate the amount of years the organisms have been in
existence. This is very useful to archaeologists and researchers.
Tracers are a common application of radioisotopes. A tracer is a radioactive
element whose pathway through which a chemical reaction can be followed.
Tracers are commonly used in the medical field and in the study of plants
and animals. Radioactive Iodine-131 can be used to study the function of the
thyroid gland assisting in detecting disease.
7. Nuclear reactors
Nuclear reactors are devices that control fission reactions producing new
substances from the fission product and energy. Recall our discussion earlier
about the fission process in the making of a radioisotope. Nuclear power
stations use uranium in fission reactions as a fuel to produce energy. Steam
is generated by the heat released during the fission process. It is this
steam that turns a turbine to produce electric energy
Other uses of radioactivity
Sterilization of medical instruments and food is another common application
of radiation. By subjecting the instruments and food to concentrated beams
of radiation, we can kill microorganisms that cause contamination and
disease. Because this is done with high energy radiation sources using
electromagnetic energy, there is no fear of residual radiation. Also, the
instruments and food may be handled without fear of radiation poisoning.
Radiation sources are extremely important to the manufacturing industries
throughout the world. They are commonly employed by nondestructive
testing personnel to monitor materials and processes in the making of the
products we see and use every day. Trained technicians use radiography to
image materials and products much like a dentist uses radiation to x-ray
your teeth for cavities. There are many industrial applications that rely on
radioactivity to assist in determining if the material or product is internally
sound and fit for its application.
HALFLIFE: This amount of time it takes for half the present
atoms of a radioactive element to decay.