O Isotopes are atoms of an element which
have the same proton number but
different nucleon number.
O Some isotopes are referred to as
'stable' and others as 'unstable' or
O Radioisotopes are unstable isotopes
which decay and give out radioactive
O Radioisotopes are naturally occuring or
O Artificial radioisotopes can be produced
when certain nuclides are bombarded by
high energy particles.
O Example :
When a nucleus of magnesium-24
is bombarded by a neutron,
sodium-24 can be produced.
O Nuclear medicine is a branch of medicine that uses
radiation to provide information about the function
of the specific organs of a patient or to treat
The rays from radium is used in the treatment of skin
Radiation from Co60 ( - rays) is used to diagnose and
treat thyroid disorders.
Radio iodine (I131) is used to diagnose and treat
Radio phosphorus (P32) is used in the treatment of
leukaemia and tumours.
Radio sodium (Na24) in the form NaCl is used to study
circulation of blood.
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O Radioactive phosphorus (P32) is used in the
study of metabolism of plants.
O Radioactive sulphur (S35) helps to study
advantages and disadvantages of
O Pests and insects on crops can be killed by
O Yield of crops like carrot, root, apples,
grapes can be increased by irradiation with
Uses of radioisotopes in
O In archaeology radioisotope carbon-14 is
used to study and estimate the age of
ancient artifacts. This method is named as
the radiocarbon dating.
O Radiocarbon dating can be used to estimate
the age of organic materials, such as wood
and leather, up to about 58,000 to 62,000
A piece of wood found in a cave of an archaeology
site has a carbon-14 activity 25% of the activity
from a live plant. Estimate the age of the wood.
[Half-life of carbon-14 = 5730 years]
100% → 50% → 25%
Carbon-14 take 2 half-life to decay from 100% to
25%, hence the age of the wood
= 11460 years
O Monitoring thickness of steel/paper
O Leaks in pipes may be traced by
introducing a small quantity of
radioisotopes into the fluid in the pipe.
O It is also used to detect the cracks in
the welding, casting etc.
O Measuring the wearing rate of engine
Monitoring thickness of
steel or paper sheets
make a proper
according to the
High reading will be
recorded if the thickness is
less than normal
Ratemeter record a high reading
above the leakage pipeGM-tube
Water added with radioactive sodium-24
1) Which statement is true about the use of
A. To determine the sex of a foetus
B. To determine the contents in the
baggage of the air plane passengers
C. To detect leakage in underground
D. To identify counterfeit bank-notes
answer : C
2) Which radioisotope can be used to
treat cancer ???
answer : B
3) Cobalt-60 destroys cancer cells
because it __________.
A has a long half-life
B has no side effect
C radiates gamma rays
D decays spontaneously
answer : C
4) The radioactive radiation used in
radiotheraphy in the treatment for
cancer is ______??
A. Beta ray
B. Alpha ray
C. Gamma ray
answer : C
5) The radioisotopes which is used to
estimate the age of archeology
specimen is ________??
answer : B
O Physics form 5 textbook
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PHYSICS A +