6.1 radioactive substances

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Chapter 6Nuclear

Energy


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6.1 Radioactive substances


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Learning Outcomes

State what is radioactive substances

Give the examples of radioactive

Substances

Explain the process of radioactive decay

State the uses of radioactive substances


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Radioactive Decay

When the radioactive nuclei break-up ordecay, 3 types of radioactive particle

or radiation is emitted;

i) Alpha()-Positive charge

ii) Beta()-Negative charge

iii) Gamma()-Neutral

Spontaneous process


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Types of Radiation


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Alpha()

radiation

Beta()

radiation

Gamma() radiation

(a)Nature Helium

nucleus

Electron Electromagnetic wave

(b)Charge Positive ( + ) Negative (-) Neutral

(c)Penetrating

powerLow High Highest

(d)Canstopped by

A sheet ofpaper

5 mmaluminium

25mm lead block orconcrete wall

e) Movement/

Speed

Slowly Very Fast Speed of light

(f)Ionizing

power

High low Very low

(g)Mass Heaviest heavy No mass

(h)Particles

or rays 2 protons &2 neutrons

One atom Ray


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Penetrating Power of theRadiation


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Uses of radioactive substance

on daily lifeField UsesIndustry Detection of leakage in underground pipes

Detection of thickness of paper, metal and plastics

Agriculture To study the absorption and distribution of elements

Gamma radiation is used to sterilize crop pests (abiological control method)

Medicine As radiotherapy treatment for cancer patientTo sterilize syringes and surgical instruments

Archeology To determine the age of ancient artifacts (carbon

dating)Foodtechnology

To preserve food


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The Uses of Radioactive Substances

Agriculture1.Gamma rays are used to- Produce new breeds of quality plants- higher yield,

earlier maturity, better nutritional value, greaterresistance to disease.

- Induce mutation in plant and animal

2. Phosphorus-32 are used as; detectors to study the absorption and use of fertiliser

(phosphate) by plants. Help farmer to determine the amount of fertiliser

need for a crop. Scientist understand how plant use phosphorus to

grow and reproduce.


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Medicine1.Gamma rays

from cobalt-60 areused to kill cancercells (radiotherapy)

also used to steriliseinstruments used inan operation

Eg: plastic syringes


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iodine-131

Check the function of bodyorgan.

to detect any damage tothe thyroid gland and check

the uptake of iodine bythyroid gland.

Patient drink liquid containiodine-131

Detector measure how fastiodine accumulates in thethyroid gland.


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Sodium-24

To detect the locationof blood clot

Inject sodium-24 intoblood stream anddetect where the flowstop.


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Industry

Geiger-Mller countercan detected theleaking pipes inunderground.


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industry

Beta particles can

be used to control

the thickness of the

paper, plastic oraluminium foil in the

mills and also be

used to ensure that

bottles andcontainers are filled

to correct level.

Figure 6.4 The thickness of paper canbe controlled by measuring how much

beta radiation passes through the

paper to Geiger counter.

( page 139)


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Food Preservation

Gamma rays canbe used to kill

bacteria, mould

and insects infood even after it

has been

packaged.

This process calledfood irradiation.


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Radioactive Dating When animals and plants

die, they stop takingcarbon, the amount ofcarbon-14 begins to declineat a know rate.

The age of the remains canbe determined bymeasuring the amount ofcarbon-14 that remains.

Method above calledcarbon-14 dating.

Archaeologists use thismethod to estimate the ageof ancient remains such asthe age of a dinosaur.


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Exercise 1

1.Give the meaning of radioactivesubstances.

2.Give two examples of radioactivesubstances and two of radioisotopes.

3.State one use of radioactive substances ineach of the following field

i) Medicine

ii) Industry

iii) Agriculture


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Production of Nuclear

Energy

Fission of Uranium-235 produce two new nucleus and releases nuclear

energy. This process is called fission of radioactive substance

6.1 radioactive substances

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