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Summary of Radioactivity: Properties and Uses

Properties of Particles

Name	Symbols	Identity	Relative Charge	Relative Mass	Penetrating Power	Interaction with Charged Plates	Hazards
alpha	, ⁴₂He	helium nucleus	2+	4	low - stopped by a sheet of paper	attracted to negative plate, deflected by positive plate	harmful if ingested

beta	, ⁰_-1e	electron	1-	1 2000	moderate - pass through paper and ½mm aluminium, stopped by ½mm lead	attracted to positive plate, deflected by negative plate	skin burns, harmful if ingested, particularly iodine-131 in thyroid & strontium-90 in bones

gamma		electro- magnetic radiation	0	0	high - only stopped by several centimetres of lead or many centimetres of concrete	unaffected	most dangerous as these are the most penetrating, as a consequence, gamma rays can be used to sterilize materials & destroy bacteria in food

Uses of Radioisotopes

Isotope	Radiation Emitted	Half-life	Use
Carbon-14	beta	5730 years	radiometric dating:determination of age of carbon-containing artifacts up to about 70,000 years also used as a biological tracer, for example, in studies of photosynthesis Naturally occurring radioisotope

Chlorine-36	beta	301,000 years	measurement of sources of chloride and determining the age of water up to about 2 million years old Naturally occurring radioisotope

Lead-210	beta	22.3 years	date layers of soil and sand deposited up to about 80 years ago Naturally occurring radioisotope

Tritium	beta	12.32 years	measure the age of 'young' groundwater up to about 30 years old Naturally occurring radioisotope Titriated water is used to study sewage and liquid wastes

Potassium-40	positron emission	1.26 billion years	Potassium-Argon radiometric dating:100 000 to several billion years

Rubidium-87	beta	48 billion years	Rubidium-Strontium radiometric dating:millions of years

Uranium/Lead	U-238 alpha & gamma	4.5 x 10⁹ years	radiometric dating:millions to billions of years

Oxygen-18	stable		biological tracer, for example, in studies of photosynthesis

Sodium-24	beta, gamma	15 hours	location of leaks in water pipes, studies of body electrolytes Isotope prepared in a nuclear reactor

Magnesium-27	beta, gamma	9.5 minutes	location of leaks in water pipes

Potassium-42	beta & alpha	22 hours	determination of exchanged potassium in blood flow Isotope prepared in a nuclear reactor

Chromium-51	alpha	27.7 days	labelling of red blood cells & quantifying gastro-intestinal protein loss Isotope prepared in a nuclear reactor

Iron-59	beta, gamma	46.3 days	in blood studies, when incorporated into steel it is used to determine the amount of friction in machinery

Cobalt-60	beta, gamma	5.3 years	cancer treatment as tumour cells tend to be more susceptible to radiation than other cells

Gallium-67	gamma	3.3 days	tumour-seeking agent Isotope prepared in a cyclotron

Krypton-81	gamma	13 seconds	Isotope prepared in a cyclotron

Technetium-99	beta	6 hours	Medical tracer used to locate brain tumours and problems with the lungs, thyroid, liver, spleen, kidney, gall bladder, skeleton, blood pool, bone marrow, salivary & lacrimal glands & heart blood pool & to detect infection Isotope prepared in a nuclear reactor

Iodine-131	beta, gamma	8.1 days	Medical tracer to study & treat the thyroid gland & used in the diagnosis of adrenal medullary & for imaging suspected neural crest and other endocrine tumours Isotope prepared in a nuclear reactor

Iodine-123	gamma	13.2 hours	used in imaging to monitor thyroid function & detect adrenal dysfunction Isotope prepared in a cyclotron

Ytterbium-169	gamma	3 days	Isotope prepared in a nuclear reactor

Uranium-235	alpha, gamma	7.1 x 10⁸ years	enriched as a fuel for most nuclear reactors

Plutonium-239	alpha, gamma	24 400 years	fuel for most "fast-breeder" nuclear reactors

Americium-241	alpha	432 years	domestic smoke alarms & neutron gauging Americium-241 is a decay product of plutonium-241 formed in nuclear reactors.

Copper-64	gamma	12.7 hours	studying genetic disease affecting copper metabolism Isotope prepared in a nuclear reactor

Iridium-192	beta	73.83 days	supplied as a wire for use as an internal radiography device

Molybdenum-99	beta	66 hours	used as the 'parent' in a generator to produce technetium-99m, the most widely used radioisotope in nuclear medicine Isotope prepared in a nuclear reactor

Phosphorus-32	beta	14.28 days	treatment of excess red blood cells Isotope prepared in a nuclear reactor

Samarium-153	beta	1.93 days	used in the treatment of pain associated with bony metastases of primary tumours Isotope prepared in a nuclear reactor

Yttrium-90	beta	64.1 hours	liver cancer therapy Isotope prepared in a nuclear reactor

Thallium-201	gamma	3 days	locating damaged heart muscle Isotope prepared in a cyclotron

Caesium-137	beta	30.2 years	radiotracing to identify sources of soil erosion & depositing, also used in thickness gauging

Gold-198	beta	2.69 days	trace factory waste causing ocean pollution and to trace sand movement in river beds and on ocean floors

Gadolinium-153	gamma	240.4 days	used in X-ray fluorescence and bone density guages for osteoporosis screening

Zinc-65	gamma	244.26 days	used to predict the behaviour of heavy metals in effluents from mining waste water

Manganese-54	gamma	312.2 days	used to predict the behaviour of heavy metals in effluents from mining waste water

Positron emitters such as carbon-11, nitrogen-13, oxygen-15 and fluorine-18 are produced in a cyclotron and are extremely short lived isotopes. They are used in positron emission tomography (PET) for studying brain physiology and pathology for epilepsy and dementia.