a2 unit5 nuclear 09 more about decay modes-4

7/25/2019 A2 Unit5 Nuclear 09 More About Decay Modes-4

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More About Decay

Modes

Nuclear Physics Lesson 9


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HomeworkHomework

Revise for the skills test.Revise for the skills test.

HWK days:HWK days:

Tues Wk 1 Period 4Tues Wk 1 Period 4

on Wk ! Period !on Wk ! Period !

Thurs Wk ! Period 4Thurs Wk ! Period 4

Nuclear Physics Test " so#e ti#e $efore halfNuclear Physics Test " so#e ti#e $efore half

ter#.ter#.


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Learning ObjectivesLearning Objectives

To inter%ret the N"& chart for radioactiveTo inter%ret the N"& chart for radioactive

isoto%es.isoto%es.

To kno' ho'To kno' ho' (()) **""andand **++ decay aredecay arere%resented on the N"& chart.re%resented on the N"& chart.

To a%%ly this to a radioactivity series.To a%%ly this to a radioactivity series.

To kno' ho' to re%resent nuclear ener,yTo kno' ho' to re%resent nuclear ener,y

levels.levels.


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The N-Z ra!hThe N-Z ra!h


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N-Z "#otN-Z "#ot


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Notes on the N-Z "#otNotes on the N-Z "#ot

-or li,ht ele#ents & / !0) N is rou,hly-or li,ht ele#ents & / !0) N is rou,hly

e2ual to & for sta$le %rotons) i.e. e2uale2ual to & for sta$le %rotons) i.e. e2ual

nu#$ers of %rotons and neutrons.nu#$ers of %rotons and neutrons.

3s the ele#ents ,et heavier) #ore3s the ele#ents ,et heavier) #ore

neutrons are needed for the stron, forceneutrons are needed for the stron, force

to overco#e the oulo#$ re%ulsion 506to overco#e the oulo#$ re%ulsion 506#ore N than & for the heaviest ele#ents.#ore N than & for the heaviest ele#ents.

so the line of sta$ility $ends u%'ards.so the line of sta$ility $ends u%'ards.


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Notes on the N-Z "#otNotes on the N-Z "#ot

((e#itters & 7 80e#itters & 7 80

**""

e#itters a$ove the sta$ility linee#itters a$ove the sta$ility line

**++e#itters $elo' the sta$ility linee#itters $elo' the sta$ility line


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Decays $e!resented onDecays $e!resented on

N-Z "#otN-Z "#otou need to kno' ho' to sho'ou need to kno' ho' to sho' (()) **""andand **++..

TH; N< W3TH; N< W3R>?N@AR>?N@A


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%&ercise%&ercise

@ra' the N"& ,ra%h for kno'n isoto%es.@ra' the N"& ,ra%h for kno'n isoto%es.

ndicate the line of sta$ility and descri$endicate the line of sta$ility and descri$e

ho' and 'hy it chan,es as & is increased.ho' and 'hy it chan,es as & is increased.

ndicate 'here thendicate 'here the (()) **""andand **++ e#itterse#itters

'ill a%%ear on the ,ra%h.'ill a%%ear on the ,ra%h. =B%lain 'hy they a%%ear in these re,ions=B%lain 'hy they a%%ear in these re,ions

of the ,ra%h.of the ,ra%h.


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Nuc#ear %nergy Leve#sNuc#ear %nergy Leve#s

3fter a nucleus has e#itted an al%ha or a3fter a nucleus has e#itted an al%ha or a

$eta %article) the dau,hter nucleus #ay$eta %article) the dau,hter nucleus #ay

$e in an eBcited state.$e in an eBcited state.

This 'ill cause it to e#it a %hoton as itThis 'ill cause it to e#it a %hoton as it

de"eBcites.de"eBcites.

t 'orks Cust like electrons #akin,t 'orks Cust like electrons #akin,transitions $et'een ato#ic ener,y levelstransitions $et'een ato#ic ener,y levels

DD but it takes !#ace in the nuc#eusbut it takes !#ace in the nuc#eus


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'a#cu#ate the !hoton'a#cu#ate the !hoton

wave#ength(wave#ength(


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%&ercise%&ercise

@escri$e the t'o 'ays@escri$e the t'o 'ays

that a 0.EF eG %hotonthat a 0.EF eG %hoton

can $e e#ittedcan $e e#itted

=B%lain ho' the $eta=B%lain ho' the $eta

decay of ,"!I candecay of ,"!I can

result in either 1 or !result in either 1 or !

%hotons $ein, e#itted.%hotons $ein, e#itted.

alculate the F %hotonalculate the F %hoton

fre2uencies %ossi$le.fre2uencies %ossi$le.


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A )igger "ictureA )igger "icture


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*ummary*ummary

3 ,ra%h of neutron nu#$er a,ainst %roton3 ,ra%h of neutron nu#$er a,ainst %roton

nu#$er sho's that there are #ore neutronsnu#$er sho's that there are #ore neutrons

in lar,er nuclei.in lar,er nuclei.

This is needed to ensure sta$ility of theThis is needed to ensure sta$ility of the

nuclei.nuclei.

=Bcited nuclei ,ive oJ ,a##a rays after=Bcited nuclei ,ive oJ ,a##a rays after

e#ittin, an al%ha %article or a $eta %article.e#ittin, an al%ha %article or a $eta %article.


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$eca!$eca!

Ho' are ,a##a rays e#itted $y theHo' are ,a##a rays e#itted $y the

nucleusnucleus

a2 unit5 nuclear 09 more about decay modes-4

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