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physics igcse > nuclear physics- topic 5 > Flashcards

nuclear physics- topic 5 Flashcards

1
Q

describe structure of an atom

A

divided in 2 parts
1. a nucleus which composed by protons and neutrons
2. negative electrons which orbit the nucleus in shells

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2
Q

how do atoms form positive vs negative ions

A

positive- lose electrons
negative-they gain electrons

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3
Q

what did the alpha particle scattering experiment prove

A

(a) a very small nucleus surrounded by mostly empty space
(b) a nucleus containing most of the mass of the atom
(c) a nucleus that is positively charged

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4
Q

how does the alpha particle scattering experiment proves what it does

A

most alpha particles pass stright through
rarely a few alpha particles are deflected by a few degrees
very rarely an alpha deflect more than 90 degrees

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5
Q

what is relative charge of proton neutron and electron

A

proton- +1
neutron- 0
electron- -1

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6
Q

what is meant by atomic number

A

number of protons in a nucleus = number of electrons if atom neutral

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7
Q

what is meant by mass number

A

nuclean number thus total number of protons and neutrons in a nucleon

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8
Q

how do you calculate number of neutrons in an atom

A

nucleon number - proton number

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9
Q

explain nuclide notation

A

mass number is normally above, and is the biggest number
while atomic number is under and smaller

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10
Q

what is meant by an isotope

A

a nucleus or atom with the same number of protons but with a different number of neutrons, have different densities but same chemical properties

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11
Q

describe nuclear fussion

A

when 2 light nuclei join together to make a heavier nucleus releasing a huge amount of energy
the mass always decreases, and energy increases due to change of mass into energy

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12
Q

describe nuclear fission

A

the splitting of a heavy nucleus into two smaller ones
mass decreases as it is converted into mainly kinetic energy as a product, thus releasing a large amount of energy

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13
Q

relationship between proton number and relative charge on a nucleus

A

proton number is the chrage of the nucleus

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14
Q

relationship between nucleon number and mass of nucleus

A

nucleon number is number of proton and neutrons added together, thus its mass

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15
Q

difference between atoms and ions

A

atoms have equal number of protons and electrons, thus are neutral
ions have different number of protons to electrons, and are charged

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16
Q

what is background radiation

A

radiation detected everywhere, such as cosmic rays, gamma rays from star, radong gas which are found in food, buildings, ourselves

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17
Q

what makes up most of background radiation

A

radon gas (in the air)
rocks and buildings
food and drink
cosmic rays

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18
Q

how can ionising nuclear radiation be measured

A

using a detector connected to a
counter

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19
Q

what is count rate measured in

A

counts/s or
counts/minute

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20
Q

how does an unstable nucleus gain stability

A

emitting one of 3 types of radioactivity, alpha, beta, gamma

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21
Q

why is a nucleus unstable

A

because it is too heavy or has too many neutrons, needs to lose them

22
Q

Describe the emission of radiation from a nucleus

A

spontaneous and random in direction

23
Q

what are the types of radioactivity

A

alpha, beta, gamma

24
Q

describe alpha particles

A

-helium nucelus (He)
-relitevly slow
-highly ioninsing (big mass and move slowly, has a large charge)
-charge of 2+
-weakly penetrating ( stopped by paper, travels only a few cm in air)

25
Q

what happens to alpha radiation in electric fields

A

moves straight and then bends into negative side, less than beta curved because of its larger mass

26
Q

what happens to alpha radiation in magnetic fields into paper

A

moves along the convectional currrent thus moves bends upwards, at constant speed

27
Q

what is the nuclear notation of helium

A

4= mass number
2=atomic number
2+=charge

28
Q

describe alpha decay equation

A

unstable particle loses 4 in the mass number and 2 in the atomic number

29
Q

describe beta radiation

A

-fast moving electrons
-less ionisation than alpha but more than gamma because beta has less mass and ke and charge than alpha but more than gamma
-penetrating abilities mid, pass throguh paper stopped by a few mm of aluminium

30
Q

describe beta particles in electric fields

A

move stright until reaches fields then radically curvs towards positive plate

31
Q

describe beta particles in magnetic fields into paper

A

moves opposite to convectional current, thus curvs downwards

32
Q

what do you use to determine the movement of radiation through magnetic fields

A

flemmings left hand rule

33
Q

describe beta decay equation

A

unstable particle simply gains +1 in its atomic number

34
Q

describe beta particle

A

electron
mass= 0
charge=-1

35
Q

what happnes to the neutron of an unstabble particle emmiting beta radiation

A

it becomes a proton and a electron

36
Q

describe gamma rays

A

-no charge or mass
-high frequency electromagnetic transversewaves
-travles in speed of light in a vaccum
-low ionisation (no charge or mass)
-only stopped by severla cm of dense lead

37
Q

what happens to gamma rays in electric and magnetic fields

A

nothing because it has no charge

38
Q

describe equation of gamma decay

A

same unsable particle + gamma in the product side

39
Q

what determines the ionising effects of each radiation

A

its charge
its mass
its relative ke

40
Q

what happens in alpha and betta decay

A

nucelus changes to that of a different element

41
Q

why can isotopes of an element be radioactive

A

due to an excess of neutrons in the
nucleus and/or the nucleus being too heavy

42
Q

what is the half life of a particular isotope

A

the time taken for half the nuclei of that
isotope in any sample to decay

43
Q

describe the radiation used in smoke detectors or fire alarms

A

alpha particules used
as smoke blocks these alpha particles from a source within the device, it doenst reach the detection sensor sets off the alarm

44
Q

describe the radiation used in irradiating food

A

gamma is used to kill bacteria in food

45
Q

describe the radiation used in sterilisation of medical equipment

A

gamma can be used

46
Q

how can you determine which type of radiation is beign emmitted

A

by putting a paper in fron tof the source, if radistion still measured, it isnt alpha radiation, you can then put an aluminium barrier and if it is measured still it is gamma

47
Q

explain radiotherapy

A

gamma rays used because of its low ionisation, it can kill cancer cells, patient exposed to short burtst of high intensity gamma radiation

48
Q

explain medical tracing or diagnosis

A

low level activity gamma radiation used, injected into patients blood stream and its movement in the brain is monitored by a g-m tube outside of body

49
Q

what are some adverse effects of ionising radiation

A

cell death, mutations and cause cancer, which might kill the organism

50
Q

how are different radioactive sources safely contained

A

store beta and alpha in lead box
and gamma burry deep underground

51
Q

what are some safety precautions when leading with ionising radiation

A

keep sources in lead box
do not point sources at people
keep distance from source and limit exposure
handle sourcs with long tongs

physics igcse (8 decks)

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