worksheet_17.doc

17 Worksheet (AS) 1

The nuclide

238 92

U

 decays by emitting α-particles and β-particles in a series of decays to form

b! b! "ig "ight α-p α-parti articl clees ar are em emitte itted d in the the se# se#uen uence! ce! $o% $o% many any β-par -parti ticl cles es are emit emitte ted d& A B C D 2

*n isotope of uranium+ %ith proton number 92 and nucleon number 23,+ emits a series of  α-particles and β-particles! hat is the proton number and nucleon number after fi.e α-particles and t%o β-particles are emitted&

4

6

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Nucleo Nucleon n number number 2(, 2(3 2(, 226

-particle in air&

α

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a fe% millimetres a fe% centimetres a fe% metres a fe% 1ilometres

n an α-particle scattering eperiment a .ery thin gold film is bombarded %ith α-particles! hat is obser.ed& A B C D

5

Proton Proton number number 80 82 8/ 86

hat can be assumed to be the maimum range of an A B C D

'()

6 8 (0 (2

A B C D 3

206 82

'()

* fe% α-particles are deflected through an angle greater than 90! 4ost α-particles are deflected through angles greater than 90!  5o α-particle continues on its original path!  5o α-particle is deflected through an angle greater than 90!

hat can be concluded concluded about about a gold nucleus nucleus %hen α-particles α-particles are scattered scattered by a thin gold gold foil& '() A B C D

The nucleus contains protons! The nucleus contains neutrons! The nucleus is much smaller than the sie of the atom! The nucleus is surrounded by electrons!

a

7i.e the name of each of the follo%ing ionising radiations i

/

ii

−( e

iii b c

2

'()

$e 0

'()



'()

hich radiation is the most ionising& hat is %rong %ith the statement belo% %ritten b y a student in his notes&  Beta-particles emitted from a radioactive material are electrons that have been been ejected  from their orbits around around the atoms.

7 :tate t%o of the properties of -radiation!

*: and * ;e.el hysics

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17 Worksheet (AS)

8 a

n each case belo%+ %rite a nuclear deca y e#uation! i

The polonium isotope

2(0 8/

o

 emits an α-particle and changes into an isotope of

lead ?b@! ii

'2)

The strontium isotope

90 38

:r   emits

a β-particle and changes into an isotope of

yttrium ?A@! b

'2)

"plain %hy the nucleon number in your ans%er to a ii do  d oes not change!

 9 Buring the transformation of the thorium isotope

232

'2)

Th  into an isotope of radon ?Cn@+

90

a total of three α-particles and t%o β-particles are emitted! Betermine the nucleon number and proton number of the isotope of radon!

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10 n an α-particle scattering eperiment+ α-particles are fired to%ards a thin gold foil! a

The diagram sho%s three α-particles approaching a gold nucleus in the foil! i

>opy the diagram and on your copy complete the paths of the α-particles!

'3)

α

α

gold nucleus

α

*dd to your diagram a dotted line to sho% the path ta1en by slo%er α-particles tra.elling initially along each of the same three lines! ;abel each of these dotted lines Dslo%E! iii "plain %hy the α-particle comes closer to the gold nucleus %hen the α-particle is initially faster!

'2)

"plain %hy this scattering eperiment leads to the conclusion that an atom i s mainly composed of empty space+ %ith a .ery small nucleus! :uggest an approimate .alue for

'2)

ii

b c

i ii 11 a

the diameter of a gold nucleus the diameter of a gold atom!

'2)

'2)

Bistinguish bet%een the random and the sontaneous nature of radioacti.e decay!

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"plain %hy the e.aporation of %ater molecules from %ater is faster at higher te mperatures  but the emission of radioacti.e particles is unchanged as the temperature temperature is raised! '2) c ;ist α+ β and -radiation+ of similar energy+ in ascending order of b

i ii iii i!

ionising ability ?ion pairs created per mm in air@ range in air mass speed!

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Total

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