nuclear physics- topic 5

Question 1

describe structure of an atom

Answer 1

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

Question 2

how do atoms form positive vs negative ions

Answer 2

positive- lose electrons
negative-they gain electrons

Question 3

what did the alpha particle scattering experiment prove

Answer 3

(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

Question 4

how does the alpha particle scattering experiment proves what it does

Answer 4

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

Question 5

what is relative charge of proton neutron and electron

Answer 5

proton- +1
neutron- 0
electron- -1

Question 6

what is meant by atomic number

Answer 6

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

Question 7

what is meant by mass number

Answer 7

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

Question 8

how do you calculate number of neutrons in an atom

Answer 8

nucleon number - proton number

Question 9

explain nuclide notation

Answer 9

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

Question 10

what is meant by an isotope

Answer 10

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

Question 11

describe nuclear fussion

Answer 11

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

Question 12

describe nuclear fission

Answer 12

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

Question 13

relationship between proton number and relative charge on a nucleus

Answer 13

proton number is the chrage of the nucleus

Question 14

relationship between nucleon number and mass of nucleus

Answer 14

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

Question 15

difference between atoms and ions

Answer 15

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

Question 16

what is background radiation

Answer 16

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

Question 17

what makes up most of background radiation

Answer 17

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

Question 18

how can ionising nuclear radiation be measured

Answer 18

using a detector connected to a
counter

Question 19

what is count rate measured in

Answer 19

counts/s or
counts/minute

Question 20

how does an unstable nucleus gain stability

Answer 20

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

Question 21

why is a nucleus unstable

Answer 21

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

Question 22

Describe the emission of radiation from a nucleus

Answer 22

spontaneous and random in direction

Question 23

what are the types of radioactivity

Answer 23

alpha, beta, gamma

Question 24

describe alpha particles

Answer 24

-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)

Question 25

what happens to alpha radiation in electric fields

Answer 25

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

Question 26

what happens to alpha radiation in magnetic fields into paper

Answer 26

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

Question 27

what is the nuclear notation of helium

Answer 27

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

Question 28

describe alpha decay equation

Answer 28

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

Question 29

describe beta radiation

Answer 29

-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

Question 30

describe beta particles in electric fields

Answer 30

move stright until reaches fields then radically curvs towards positive plate

Question 31

describe beta particles in magnetic fields into paper

Answer 31

moves opposite to convectional current, thus curvs downwards

Question 32

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

Answer 32

flemmings left hand rule

Question 33

describe beta decay equation

Answer 33

unstable particle simply gains +1 in its atomic number

Question 34

describe beta particle

Answer 34

electron mass= 0 charge=-1

Question 35

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

Answer 35

it becomes a proton and a electron

Question 36

describe gamma rays

Answer 36

-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

Question 37

what happens to gamma rays in electric and magnetic fields

Answer 37

nothing because it has no charge

Question 38

describe equation of gamma decay

Answer 38

same unsable particle + gamma in the product side

Question 39

what determines the ionising effects of each radiation

Answer 39

its charge its mass its relative ke

Question 40

what happens in alpha and betta decay

Answer 40

nucelus changes to that of a different element

Question 41

why can isotopes of an element be radioactive

Answer 41

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

Question 42

what is the half life of a particular isotope

Answer 42

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

Question 43

describe the radiation used in smoke detectors or fire alarms

Answer 43

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

Question 44

describe the radiation used in irradiating food

Answer 44

gamma is used to kill bacteria in food

Question 45

describe the radiation used in sterilisation of medical equipment

Answer 45

gamma can be used

Question 46

how can you determine which type of radiation is beign emmitted

Answer 46

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

Question 47

explain radiotherapy

Answer 47

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

Question 48

explain medical tracing or diagnosis

Answer 48

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

Question 49

what are some adverse effects of ionising radiation

Answer 49

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

Question 50

how are different radioactive sources safely contained

Answer 50

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

Question 51

what are some safety precautions when leading with ionising radiation

Answer 51

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