Chapter 5 RADIOACTIVITY5.3 THE USES OF RADIOISOTOPESA student is able todefne radioisotopes.name examples of radioisotopes.describe applications of radioisotopes.5.3 THE USES OF RADIOISOTOPESRadioisotopesIsotopes of an element hae the same chemical properties and the same number o protons.Radioactie isotopes are called ra!ioisotopes.Radioisotopes are unstable isotopes !hich deca" and #ie out radioactie emissions.5.3 THE USES OF RADIOISOTOPESRadioisotopesTable belo! #ies a list of some radioisotopes.5.3 THE USES OF RADIOISOTOPESAPPLICATIONS OF RADIOISOTOPESSmo"e Detectors$mo%e alarms contain a !ea% source made of Americium&'().Alpha particles are emitted from here* !hich ionise the air* so that the air conducts electricit" and a small current +o!s.If smo%e enters the alarm* this absorbs the a particles* the current reduces* and the alarm sounds.Am&'() has a half&life of (,- "ears.5.3 THE USES OF RADIOISOTOPESAPPLICATIONS OF RADIOISOTOPESThic"ness #ontrolIn paper mills* the thic%ness of the paper can be controlled b" measurin# ho! much beta radiation passes throu#h the paper to a .ei#er counter.The counter controls the pressure of the rollers to #ie the correct thic%ness.5.3 THE USES OF RADIOISOTOPESAPPLICATIONS OF RADIOISOTOPESThic"ness #ontrol/ith paper* or plastic* or aluminium foil* 0 ra"s are used* because 1 !ill not #o throu#h the paper./e choose a source !ith a lon# half&life so that it does not need to be replaced often.5.3 THE USES OF RADIOISOTOPESAPPLICATIONS OF RADIOISOTOPESSterilisin$2en after it has been pac%a#ed* #amma ra"s can be used to %ill bacteria* mould and insects in food.This process prolon#s the shelf&life of the food* but sometimes chan#es the taste..amma ra"s are also used to sterilise hospital e3uipment* especiall" plastic s"rin#es that !ould be dama#ed if heated.5.3 THE USES OF RADIOISOTOPESAPPLICATIONS OF RADIOISOTOPESRa!ioacti%e Datin$Animals and plants hae a %no!n proportion of Carbon&)( 4a radioisotope of Carbon5 in their tissues.5.3 THE USES OF RADIOISOTOPESAPPLICATIONS OF RADIOISOTOPESRa!ioacti%e Datin$/hen the" die the" stop ta%in# Carbon in* then the amount of Carbon&)( #oes do!n at a %no!n rate 4Carbon&)( has a half&life of 56-- "ears5.The a#e of the ancient or#anic materials can be found b" measurin# the amount of Carbon&)( that is left.5.3 THE USES OF RADIOISOTOPESAPPLICATIONS OF RADIOISOTOPESRa!ioacti%e TracersThe most common tracer is called Technetium&77 and is er" safe because it onl" emits #amma ra"s and doesn8t cause much ionisation.Radioisotopes can be used for medical purposes* such as chec%in# for a bloc%ed %idne".5.3 THE USES OF RADIOISOTOPESAPPLICATIONS OF RADIOISOTOPESRa!ioacti%e TracersTo do this* a small amount of Iodine&)'9 is in:ected into the patient* after 5 minutes ' .ei#er counters are placed oer the %idne"s.Also radioisotopes are used in industr"* to detect lea%in# pipes. To do this* a small amount is in:ected into the pipe. It is then detected !ith a .; counter aboe #round.5.3 THE USES OF RADIOISOTOPESAPPLICATIONS OF RADIOISOTOPES#ancer Treatment