Radioactivity

transcript

INTRODUCTION TO RADIOACTIVITY

Presenters: Damion Lawrence and Michael Ward

PREREQUISITE KNOWLEDGE

▪ For mastery of the content presented in this presentation, students should have been taught:– Atomic Structure

– The reason an atom is normally neutral and stable

– What is meant by the term Isotope

PRESENTATION OBJECTIVES

At the end of this presentation, students will:

i. be familiar with the phenomenon of radioactivity and the safety measures when dealing with radioactive substances.

ii. be able to state the nature of the three types of radioactive emissions.

iii. be able to discuss the useful applications of radioisotopes.

Radioactivity(SECTION E: SPECIFIC OBJECTIVE 3.2 )

▪ Radioactivity, spontaneous disintegration of atomic nuclei which accompanies the emission of subatomic particles and electromagnetic energy (i.e. alpha particle and beta particle, or of electromagnetic and gamma rays).

TYPES OF NATURAL RADIOACTIVE EMISSIONS(SECTION E: SPECIFIC OBJECTIVE 3.2 )

1. Alpha Radiation (Alpha Particle)

2. Beta Radiation (Beta Particle)

3. Gamma Radiation (Gamma Ray)

ALPHA RADIATION(SECTION E: SPECIFIC OBJECTIVE 3.2 )

▪ Alpha radiation consists of alpha particles. An alpha particle is identical to the nucleus of a helium atom, which comprises two protons and two neutrons.

BETA RADIATION(SECTION E: SPECIFIC OBJECTIVE 3.2 )

▪ Beta radiation consists of high energy electrons emitted from the nucleus. These electrons have not come from the electron shells or energy levels around the nucleus. Instead, they form when a neutron splits into a proton and an electron. The electron then shoots out of the nucleus at high speed.

GAMMA RADIATION (SECTION E: SPECIFIC OBJECTIVE 3.2 )

▪ Gamma radiation is very short wavelength - high frequency -electromagnetic radiation. This is similar to other types of electromagnetic radiation such as visible light and X-rays, which can travel long distances.

PENETRATING PROPERTIES OF RADIATION(Section E )

▪ Radiation can be absorbed by substances in its path. For example, alpha radiation travels only a few centimetres in air, beta radiation travels tens of centimetres in air and gamma radiation travels many metres. All types of radiation become less intense the further the distance from the radioactive material, as the particles or rays become more spread out.

PENETRATING PROPERTIES OF RADIATION

▪ The thicker the substance, the more the radiation is absorbed. The three types of radiation penetrate materials in different ways.

PENETRATING PROPERTIES OF RADIATION (ALPHA RADIATION).

▪ Alpha radiation is the least penetrative. It can be stopped -or absorbed - by just a sheet of paper.

PENETRATING PROPERTIES OF RADIATION (BETA RADIATION).

▪ Beta radiation can penetrate air and paper. It can be stopped by a thin sheet of aluminum.

PENETRATING PROPERTIES OF RADIATION (GAMMA RADIATION).

▪ Gamma radiation is the most penetrative. Even small levels can penetrate air, paper or thin metal. Higher levels can only be stopped by many centimetres of lead or many metres of concrete.

HANDLING RADIOACTIVE MATERIALS(SECTION E: SPECIFIC OBJECTIVE 3.11 )

1. Radioactive materials should be handled with tools such as forceps-never with the bare hands

2. Sources should never be pointed towards people or other living organisms. Sources should never be brought near the eyes.

3. There must be no eating or drinking where radioactive materials are being used.

4. After use, radioactive materials should be stored in lead containers and placed in a locked , isolated metal cupboard.

5. After using radioactive materials , the user must wash his/her hands thoroughly before eating.

6. Equipment capable of detecting radioactivity must be present to check for radioactive emissions.

USES OF RADIOACTIVE ISOTOPES(SECTION E: SPECIFIC OBJECTIVE 3.11 )

Radioactive isotopes have a variety of applications. They are useful because we can detect their radioactivity and we can use the energy they release

Radiometric dating:

radioactive isotopes are useful for stablishing the ages of various objects. The half-life of radioactive isotopes is unaffected by any environmental factors, so the isotope acts like an internal clock.

▪ The most common Radiometric dating is known as Carbon Dating. By using the half life of carbon-14 we can determine the age of various objects that were once living, such as bones.

Irradiation of Produce

The radiation emitted by some radioactive substances can be used to kill microorganisms on a variety of foodstuffs, which extends the shelf life of these products. This exposure kills a lot of the bacteria that cause spoilage, so the produce stays fresh longer. Eggs and some meat, such as beef, pork, and poultry, can also be irradiated.

MEDICAL IMAGING

In nuclear medicine, tiny amounts of a radioactive form of these elements are introduced into a patient’s body. The “radioisotopes” are picked up by specific organs, enabling a special camera to take a picture of how that organ is functioning in striking detail

USES OF RADIOACTIVE ISOTOPES

▪ TRACERS

Radioactive isotopes are effective tracers because their radioactivity is easy to detect. A tracer is a substance that can be used to follow the pathway of that substance through some structure. For instance, leaks in underground water pipes can be discovered by running some tritium-containing water through the pipes and then using a Geiger counter to locate any radioactive tritium subsequently present in the ground around the pipes.

▪ CHEMOTHERAPY

Radiation damages the DNA of the cancer cells, causing them to die. Radiation therapy uses high-energy radiation to shrink tumors and kill cancer cells . X-rays, gamma rays, and charged particles are types of radiation used for cancer treatment.

SYMPTOMS OF RADIOACTIVE SICKNESS(SECTION E: SPECIFIC OBJECTIVE 3.13 )

1. Loss of body hair

2. Nausea

3. Fatigue

4. Drop in white blood cell count

5. Sterility after over-exposure

QUESTION 1

Radioactivity is the:

a. Spontaneous disintegration of atomic nuclei which accompanies the emission of subatomic particles and electromagnetic energy.

b. nuclear energy required to achieve stability in the nucleus of an atom.

c. nuclear energy required to split the nuclear of an atom

d. nuclear energy required to convert an element into a different element

QUESTION 2

All are radioactive emissions EXCEPT:

a. Alpha Particle

b. Beta Particle

c. Gamma ray

d. Nuclear Fission

QUESTION 3

The most penetrative emission is:

a. Alpha Emission

b. Neutron

c. Beta Emission

d. Gamma Emission

QUESTION 4

All of the following are safety precautions when handling radioactive materials EXCEPT:

a. Radioactive materials should be handled with tools such as forceps-never with the bare hands.

b. Sources should never be pointed towards people or other living organisms. Sources should never be brought near the eyes.

c. There must be no eating or drinking where radioactive materials are being used.

d. Radioactive materials should be placed in a plastic container immediately after use.

QUESTION 5

Which emission has the furthest range:

a. Alpha Emission

b. Neutron

c. Beta Emission

d. Gamma Emission

QUESTION 6

All of the following are uses of Radioactivity EXCEPT:

a. Chemotherapy

b. Irradiation of Produce

c. Carbon Dating

d. Barcode reading

GLOSSARY OF TERMS

▪ Emission: the act of sending out gas, heat, light, etc

▪ Fatigue: Fatigue is a term used to describe the general overall feeling of tiredness and/or a lack of energy.

GLOSSARY OF TERMS

▪ Isotope : Any atom having the same atomic number but different mass number. In other words, they have the same number of protons and electrons but different number of neutrons.

GLOSSARY OF TERMS

▪ Nuclei : plural of nucleus ( i.e. the central part of an atom that comprises nearly all of the atomic mass and that consists of protons and neutrons)

GLOSSARY OF TERMS

▪ Nausea: feeling an urge to vomit.

▪ Spontaneous: unplanned or occurring unexpectedly .

GLOSSARY OF TERMS

▪ Sterility: Not producing or incapable of producing offspring

▪ Subatomic Particles: Particles that are smaller than the atom are called subatomic particles. The three main subatomic particles that form an atom are protons, neutrons, and electrons.

Radioactivity

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