Radioactivity Flashcards
What does a particle contain
Protons Neutrons Electrons
What charge does each particles have
e=- pro= + neut= neutral
What prbit around the nucleus?
electrons
How can electrons move between energy levels?
electrons can move up energy levels by absorbing energy
down by releasing energy
all matter is made from (1)
the element copper is a metal that is just made from (2) atoms
an attom has a (3) whihc contains (4)
negativley charged particle called (5) orbit around the (6)
atoms have no overall charge so they are said to be (7)
1 atoms 2 copper 3 nucleus 4 protons 7 electrons 6 nucleus 7 neutral
the relative charge and relative mass of Protons, Neutrons and electrons
p rc= +1 rm = 1 N rc=0 rm=1 E rc=-1 rm=0
What is atomic mass
top number
#protons and neutrons in nucleus
(#particles in nucleus)
what is the Atomic number
#of protons in nucleus #p=#e
define Isotope
the atoms of a element with diffrent numbers of neutrons. they have the same proton number but diffrent mass numbers
Why are some isotopes radioactive?
their neutron/proton ratio are too large/small
What determines an nucleus’ stability
n/p ration
what happends when a nucleus has a too large or too small n/p?
unstable
decays to form a more stable nucleus
how does an unstable isotope decay
emits radiation to form a more stable isotope (radioactiviy)
Why are some nuclei radioactive?
radioactivity
the property possesed by unstable elements of spontaneously emmiting energetic particles (beta/alpha) by the decay of their atomic nuclei on order to becom stable
how do unstable nuclei become stable
releasing particles from their nucleus in order to change the p/n
3 types of radiation
alpha
beta
gama
what is alpha radiation
a helium nucleus 2 p 2 n stopped by paper or a few cm of air strongly ionising weakly deflected
what is a beta ionising radiation
high energy electron
stopped by thin aluminium
weakly inoising
strongly deflected
what is gamma ionising radiation
an em wave (left over energy)
REDUCED by several cm of lead of meters of concrete
very weakly ionising
no deflection
what do alpha,beta and gamma do to an atom
pull electrons away from atoms
describe the use of radiation in smoke detectors
alpha
source pass to detector
smoke stops alpha partices reaching detector
alarm sounds
since very ionising / least penetrating
its stopped by smoke particles
describe the use of beta in thickness of paper
beta source passes through paper
amount of particles detected on other side
too few pass through = paper to thik, roller pressure increase
too many pass through paper = paper thin, roller preassure decreased
describe the role of gamma in leaks in pipes
radioactive isotop injected into pipe
detector is moved along the ground above the pipe
leak is located where theres an increase in activity and little or no activity after this point
describe alpha decay
when an alpha particle is emmited from a nucleus, the nucleus loses 2 protons and 3 neutrons
meaning mass # decreases by 4 and atomic # decreases by 2
What are the constants in alpha decay
mass decrease by 4 # decrease by 2
describe beta decay
beta perticle = electron emited from nucleus
occurs when:
too many protons, neutrons
one of protons or neutrons = transformed into other
in beta minus decay, a neutron decays into a ptroton releasing an lectron
describe nuclei decay
completley random.
heating up source/cooling it down/squashing it/ breaking it up etc. has no efects
matter of probability
define half life
time it takes for the # of nuclei of the isotope in a sample to 1/2
time it takes for the count rate from sample containing the isotope to fall to half of its starting level
what is background radiation
exposure to a certain amount of nuclear radiation every day
list the medical uses of nuclear radiation
cancer treatment
imaging
tracers
how does a medical tracer work
half life
66 hrs
short half life and decays before it can do much damage
long enough to pass through body and be detected
decays into stable isotope
how does a gamma camera work
allows radiologists to carry out tests providing detailed diagnostics about functioning of the thyroid, heat, lungs etc.
half life
66 hrs
short hal life and decays before much damage is done
long enough to pass thorugh body detected
decays into stable isotope
how does a gamma knife work
gives you high doses of radiation
targeted to reach very small part of brain so it doesnt damage surrounding healthy tisues
half life
5.7 years
doesnt remain in body so half life doesnt matter
relativley stable, will not decay before it is used
how does radiotherapy work
high dose of gamma directed to kill cancerous cellls
from outside using x rays from radioactive cobalt
from inside by putting radioactive material into tumor or close to it
half life
5.7 years
doesnt remain in body so half life doesnt matter’relatively stable
wont decay before its used
describe a radioactive implant
small radioacltive source placed directly on tumor
small dose of gamma is given over a long period of time directly into the tumor (killing cells)
what is the diffrence between a nuclear reactor and a nuclear bomb
nuclear power and nuclear bombs usually use a radioactive source (uranium usually)
both radioactive source under go fission to produce energy, but one explodes and the other doesent
describe nuclear power
energy is released in a nuclear reactor because of nuclear fission
3 types of fission
nuclear - unstable nuclei splits toform 2 smaller nuclei spontaneous - rare induced
descrube the fission process
neutron travels at high speed towards a nucleus
neutron strikes nucleus and captures a neutron
nucleus = unstable
transforms into elpngated shape for short time
splits into 2 fission fragments and releases neutrons
how does fission relase energy
KE of products pf fissionare far greater than that of a bombarding neutron and target atoms
this enery is released as heat and used in nucclear reactors
what is thermonuclear fusion
nucleasr FUSION occurs when nuclei are fused togather
generates heat energy
product aren’t radioactive
