Phys content purely

radioisotope

isotope that emits radiation due to unstable comb of n and p

isotope

atom of element (same p) but has different neutrons (mass num diff)

Z

atomic number

A

mass number

isotope chemical

same because of same e numb

isotope physical

differ due to diff mass numb

physical properties eg

density, rate of diffusion and boiling point

fundamental force

force that cannot be explained in terms of action of other forces

gravity

acts between objects with mass

gravity particles

all particle with mass

gravity force carrier

gravitation (not yet observed)

gravity range

infinity

gravity relative strength

weakest

weak force

governs particle decay

weak force particles

quarks and leptons

weak force carrier

W+, W-, Z0

weak force range

short

em

acts between electrically charged particles

em affect particle

electrically charged

em carrier

photon

em range

infinity

snf

binds quarks together

snf particles

quarks and gluons

snf carrier

gluon

snf range

short range

forces ordered from weakest to strongest relatives strength

1. grav

2. weak

3. em

4. snf

radioactive decay is...

random event

radioactive decay random mean

cannot predict when unstable nuclei decay

you cant... (radioactive decay)

do anything to make it happen (excluding induced)

radioactive decay important note

not affected by changes in pressure or temp

decay constant units

s^-1

half life and activity

shorter half life, higher activity

increased decay constant mean

more likely a nucleus will decay

baryon

particle made up of 3 quarks

snf acts.. (btw particles)

equally between all particles

why large elements unstable

- as more p, more em repulsion

- snf acts adjacently, em infinite range

- as em repulse increase, not enough snf to balance

•Describe how the strong nuclear force between two nucleons varies with separation of the nucleon quoting suitable values for separation

•Repulsive then attractive

•Short range (fm) up to 4/5 fm

•Crossover at 0.5 fm

heaviest stable element

lead

decay energy

output of e from radioactive decay

decay energy in alpha

Ek of daughter nucleus and alpha particle shared at fixed rate

alpha particles are

monenergetic

alpha particle what

helium nuclei

beta - happen in

neutron rich

beta -

n -> p, Ve, e-

beta + where

proton rich

beta +

p -> n, antiVe, e+

beta decay energy

vary in e, have max energy

beta energy max energy when

all e is split unevenly between Ve and e, daughter nucleus does not have any

gamma

emitted if nucleus has too much energy after a or b emission

nucleus has too much energy after a or b emission called

excited state

alpha speed desc

heavy and slow moving

alpha speed number

0.1c`

alpha energy

5-10 MeV

alpha penetrating power

- air few cm

- thin card/human hand

- poor penetration

beta energy

1-5 MeV

beta speed

0.9c

beta - penetrating

- air 1-2cm

- aluminium

beta + penetrating

annihilates

gamma speed

speed of light

speed of light

3 x 10^8 m/s

gamma energy

<1 MeV

gamma penetration

- air infinite range

- cms of lead

- ms of concrete

half life def

average time it takes for activity to halve

activity def

num nuclei that decays per second

decay constant def

probability that a given nuclei will decay per second

radiation detection

photographic film, geiger muller tubes

bg rad in aus

1.5-2 mSv

woldwide rad avg

2.4mSv

fatal dose

2 Sv

natural sources radiation

- food and drink

- cosmic rays

- uranium mines

artificial sources radiation

- air travel

- medical xrays

- nuclear industry

why use dose equivalent

absorbed dose does not take into account of radiation involved

absorbed dose def

energy deposited in 1kg of substance by radiation

why alpha most ionising

- low speed

- high charge

- large mass

interact w and ionise every atom in path

why e release in nuclear fission/fusion answer struc

- what happens

- mass of reactant bigger than product

- difference in mass = e

mass defect

difference between mass of reactants and mass of products

binding energy

energy required to split nucleus into constituent nucleons

binding energy also

provides extra mass for nucleon to exist separately

why fusion release more energy

- graph steeper, bigger difference in binding energy

- bigger yield more energy released

yield definition

amount of energy released in a nuclear reaction

fission

splitting of large atomic nucleus to form two smaller ones

fusion

combining 2 smaller nuclei to create a larger one

fusion happen if

nuclei has enough e to overcome electrostatic repulsion btw p to be attracted by snf

mass of atom is where

most of it in nucleus

relative mass

simple mass and charge (1etc)

annihilation

antimatter particle meets normal particle and annihilates

spontaneous transmutation eg

U-238 into Pb-206

induced transmutation eg

fire neutron at U-235

hadron

3q, or q+ antiq

meson

quark and antiquark pair

boson

force carrier

iodine 131 used to

treat certain types of thyroid cancers

nz graph smaller elements

N ~ z = linear line;

nz graphs larger elements

require more n for stability, graph begins to curve

nz graph top

beta -

nz graph bottom

beta +

at the top nz graph

alpha

ev

smaller unit for energy

danger of alpha

ingested increase cancer risk

danger of beta

skin burns