radiation Flashcards
what are the 3 types of particles that make up the atom
proton
neutron
electron
what particles are found in the nucleus
protons and neutrons
what orbits the nucleus
electrons
charge and mass of a proton
+1
1
charge and mass on neutron
0
1
charge and mass of electron
-1
1/1836
the nnumber of protons is called
the atomic number
the number of protons and neutrons is called
the mass number
what are nucleons
protons and neutrons
what experiment did rutherford carry out
alpha scattering experiment
what did rutherfords experiment show
that alpha particles ca pass through thin gold foil
what did he do in this experiment
he fired aplha particles at thin golf foil. detectors were used to find how thr alpha particles were scattered by the gold atoms
rutherfords explanation
rutherford showed that this could be explained if each atom has a tiny core or nucleus with a positive charge. a positive nucleus repels positive alpha particles so that they are scattered in different directions
observation: most of the aplha particles went straight through the foil
explanation:
nucleus must be tiny (easy for alpha particles to miss)
obervation: some particles were slightly deflected
explanation:
nucleus is charged
obervation: a few particles “bounced” staight back
nucleus is positively charged and has much more mass than the alpha particle
3 types of radiation
alpha
beta
gamma
symbol equation for alpha particle
4 4
He or ∝
2 2
symbol equation for beta particle
0 0
B or e
-1 -1
where does rutherfords experiment happen
a vacuum
when writing symbol equations it is important to remember that:
-mass numbers must balance
-atomic numbers must balance
background radiation comes from:
rocks in the ground
bricks in building
nuclear waste from power stations and bomb tests
hospitals
outer space
how do u measure background radiation
set up a G-M tube with no radioactive sources present
measure the count over a long period of time
divide the number of counts by the time to get the count rate in whichever unit is appropriate
what is a corrected count rate
one which has the background rate suntracted from it
what is meant by background radiation
radiation that is present in our enviroment all ready
why is it vital that radiation doesnt get into r food chain
radioactivity is much more dangereous insude the body
what does ionising radiation mean
radiation that can remove electrons from atomd in its path, so it has an ionising effect
the range of radioactivity is …
how far we could expect it to travel in a particular material before being stopped
why is ionising radiation so dangerous
when a molecule of genes in living cells is ionised, the genetic material of a cell id damaged and may become cancerous
name the 3 forms of nuclear radiation
alpha- ∝
beta- β
gamma- γ
dangers of radioactivity for living cells
when radiation collides with molecules in living cells it damages them. if the DNA in the nucleus of a cell is damaged, the cell may become cancerous. the cell then goes out of control, divides rapidly and causes serious health problems
radiations is harmful because of its …
penetrating nature, and its ability to ionise
why is alpha radiation the most dangerous inside the body
because it is easily absorbed by cells
what type of radiation is the most dangerous inside the body
alpha radiation
what type of radiation is the least dangerous inside the body
beta and gamma
why is beta and gamma radiation not as dangerous inside the body
because they are less likely to be absorbed by a cell and will usually just pass right through
what type of radiation is the least dangerous outside the body
alpha
what type of radiation is the most dangerous outside the body
beta and gamma
why is alpha radiation not as dangerous outside the body
because it is unlikely to reach living cells inside the body
why is beta and gamma radiation dangerous outside the body
because they can penetrate the skin and damage cells inside
protection when handling radioactive sources
-wearing protective clothing
-keeping the source as far away as possible by using tongs
-limiting the exposure tome to as little as possible
-keeping radioactive materials in lead lined containers
uses of radioactivity
-in smoke detectors
-for sterilising medical instruments
-for killing cancer cells
-for dating rocks and materials such as archaeological finds
-in chemical tracers to help with medical diagnosis
-for measuring the thickness of materials in, for example a paper factory
decay is _____________________
random and spontaneous
what does random mean
we can’t predict when it will happen
what does spontaneous mean
it happens on its own without are influence
definitions of half life
- the time for the number of undecayed nuclei to fall to half of its previous volume
- the time for the activity to fall to half of its previous value
what is nuclear fission
occurs when a large nucleus splits into two or more smaller nuclei
where is nuclear fusion used
used in nuclear power stations to generate electricity
summary of what happens in fission
uranium nucleus absorbs a neutron, then splits into two or more smaller nuclei, releasing energy, and several neutrons. these neutrons can then go on to cause other reactions and cause a chain reaction
what is nuclear fusion
occurs when two light nuclei (hydrogen) join to form a new heavier nucleus (helium)
where does nuclear fusion occur
in stars- it is the source of their energy
what elements are used in fusion
isotopes of hydrogen
name the 3 forms of hydrogen
hydrogen
deuterium
tritium
write out a typical fusion reaction
2/1 H + 3/1 H → 4/2 He + 1/0 n + energy
what conditions are required for fusion reactions to occur
extremely high temperatures and pressure
why is fusion seen as a potential solution to solve the energy crisis
-the isotopes of hydrogen are widely available as the constituents of seawater
-fusion does not emit carbon dioxide or other green house gases into the atmosphere
- its major by-product is helium, which is inset and non-toxic
how does fusion compare to fossil fuels and fission in terms of energy output
- fusion releases 4 million times more energy per kg than burning coal, oil or gas
- fusion releases 4 times as much energy as nuclear fission reactions per kg
