Please enable JavaScript.
Coggle requires JavaScript to display documents.
Radioactivity and Particles - Coggle Diagram
Radioactivity and Particles
structure of an atom
electrons -
neutrons 0
protons +
terms
mass number
is the total number of protons and neutrons in the nucleus of an atom
an isotope
is an atom of the same element with the same proton number but with a different mass number
atomic/proton number
is the number of protons in the nucleus of an atom
Geiger-Muller detector
when connected to a counter, it can measure radioactivity
photographic film
the film will darken in the presence of ionising radiation
half-life
is the time taken for the radioactivity of a specific isotope to fall to half its original value
irradiation
is the process by which an object is exposed to radiation but does not become radioactive itself
contamination
occurs when material that contains radioactive atoms is deposited on materials, skin, clothing, or any place where it is not desired
control rods
absorb neutrons and completely remove them from the fission process and this helps adjust the rate of nuclear fission in the reactor (made of boron or cadmium)
moderator
absorbs kinetic energy of the neutrons to slow them down as they are more easily absorbed by U-235 (graphite is used)
shielding
prevents any radiation escaping, even neutrons and it is made out of steel and surrounded by aa 5m thick layer of concrete
these particles are ionising radiations emitted from unstable nuclei in a random process
beta
β
moderate ionising + moderate penetrating
1m
stopped by 5mm of aluminium and is a fast moving electron
gamma
γ
weakly ionising + most penetrating
at least 1km
stopped by 10cm of lead and is a electromagnetic wave
alpha
α
strongly ionising + least penetrating
a few cm
stopped by paper and has a
helium nucleus
ionisation is a process where an atom loses or gains electrons and becomes a charged ion
important units
hour
h
min
cm
becquerel
Bq
- measures the activity of a radioactivity source (which decreases over time)
s
PRACTICAL: investigate the different penetration oiwers of different typed of radiation
detect using a
Geiger-Muller Tube
try 3 different materials in order: paper, aluminium and lead for each sample
the count rate of the Geiger-Muller tube will decrease significantly if radiation is stopped (but there will still be some due to background radiation)
radioactive decay
beta
mass number 0
atomic number +1
i neuton is converted to an electron and proton
gamma
mass number 0
atomic number 0
energy is lost from an atom is the form of an EM wave
alpha
2 protons and 2 neutrons are lost
mass number -4
atomic number -2
sources of background radiation
granite in rocks
cosmic rays
radon in air
medical equipment
food and drink
uses of radiation
medical tracer- put in body (swallowed/injected), detector put around body, computer generates an image
gauging- coal absorbs a lot of radiation
gamma radiography
radiotherapy- high does of radiation are directed t cancer cells to kill them
pipe tracers- radioactive material with a short half-life is put into the water and a detector is placed above the pipe and a spike in detected radioactivity suggests a leak in the pipe
sterilisation- medical equipment irradiated, and the radiation kills all living matter on tools (bacteria)
carbon dating- knows how old things are
dangers of ionising radiation
radiation can cause mutations in living organisms
the radiation can damage cells and tissue
the problems arising from the disposal of radioactive waste (explosions)
nuclear reactions
fusion
the process where lighter atoms are forced to join together to make heavier atoms (releasing energy)
radioactive decay
radioactive isotopes of elements provide a large proportion of heat within the earth through radioactive decay
fission
the process where heavy atoms are split into smaller, lighter atoms (releasing energy)
U-235
fission of U-235 produces two radioactive daughter nuclei and a small number of neutrons
a slow moving electron is absorbed
resulting in an unstable U-236 nucleus
this splits into 2 smaller daughter nuclei, three neutrons and gamma radiation
chain reaction
for a chain reaction to occur, there is a minimum mass of U-235 required (critical mass)
the 3 neutrons produced by fission may hit other nuclei of U-235, causing the process to repeat
nuclear fusion is the source of energy for our sun and stars
nuclear fusion cannot happen at low temperatures and pressures due to electrostatic repulsion of protons, so a lot of energy is needed to overcome them and high pressures are needed to increase he chance of fusion between the nuclei