3. Radiation / Nuclear decay Flashcards
What is Rutherfords alpha scattering experiment
The first time where scientists found the new atomic diagram / structure of particles
What is an alpha particle
A helium nucleus that is highly ionising and cannot penetrate through paper
What is a beta particle
Very fast electron that is medium ionising and can be stopped by thin steel
What are gamma particles
High energy photons of em radiation that can only be stopped by thick lead
What is background radiation
Radiation that occurs naturally from surroundings
Give examples of back ground radiation
Cosmic rays
Medical equipment
Radon gas
Food
What is activity
The number of decays taken place per second
Units of activity
Becerquels (Bq)
What is a Bq
A single decay of a nucleus per second
What is half life
The amount of time taken for half the radioactive nuclei to decay.
The time taken for the number of radioactive nuclei to become half
What does it mean by spontaneous
When an atom or nucleus decays without any trigger such as heat or light ect… it is unprovoked
Half life equation
T½ = ln2 / Y
Y = decay constant
activity equation
A = - Y x N
Name two applications of radioactivity
Tracers = finding leaks in pipes
Carbon dating
Medical = MRI, radio therapy
what is the difference between irradiation and contamination
Irradiation is the process by which an object is exposed to radiation, including radiation from the nuclei of atoms
Contamination is if the object has been introduced to a radioactive material eg on clothing or skin
How is radiation hazardous?
Radiation can cause cell mutation and uncontrolled cell growth
It ionizes cells
If exposed to high dosages of radiation then cells can be damaged faster then they are replaced causing radiation sickness and poisoning
Example of misuse of radioactive material
Alexander Litvineko - poisoned with polonium isotope 210 which emits alpha radiation causing him to die of radiation sickness
definition of nuclear binding energy
The energy released when a nucleus forms = the work done in separating a nucleus into atoms
Why is radon gas particularly dangerous
It is very dense so when released from rocks it settles at lower levels meaning in an area of houses with radon rocks, basements can be filled with radioactive gases unknowingly.
It is highly ionising and can also contaminate water supplies and wells
How does gamma radiation interacts with matter
The photoelectric effect
definition of mass defect
the difference in mass from when it is before then after it is formed
what is the equation that related energy to mass
e = mc^2
what is the most stable element
iron
what is the atomic mass unit
1 u = 1.66 x10 ^-27
What is the binding energy per nucleon
the amount of binding energy / the nucleon number
What are the different sides of a MeV- Nucleon number graph
to the left of iron = fusion (they are smaller particles needing to be binded together)
to the right of iron = fission (they are larger particles that are separated)
What is the differences between fission and fusion?
fission: always have neutrons produced , Splits up atoms , generated electricity , has a chain reaction
fusion: joins up atoms, needs to overcome repulsion , uses high pressure and high speeds for the reaction
What are the components of a nuclear reactor
control rods
coolant
moderator
fuel pods /elements
what is the purpose of the control rods
used to control the rate of fission to stop the reactor from overheating and causing a core meltdown. they absorb all but one neutron stopping the chain reaction from continuing.
How does the release of nucleons lead to a chain reaction
The neutrons released will be absorbed by other element nuclei , these will then split producing more neutrons, these will then be absorbed and the process continues
what is the conservation of mass energy
mass can be converted to energy using einsteins equation so the amount of mass and energy is constant even if there is a change in mass
e=mc^2
What things are conserved in a nuclear reaction
the nucleon number
the proton number
mass - energy
momentum
how do each of the radioactive particles react in a magnetic field?
Force in electric field = Eq
Magnetic force = Bvq
Alpha particle = +2e charge = little force = big mass = no deflection
Beta particle = -1e charge = half forces of a = little mass = larger deflection
Gamma particle = no charge = no deflection
Why is energy released in reactions on a fission/fusion graph?
The energy released comes from the reduction in mass as it is converted into energy
E=mc^2
Give a benefit and issue of a nuclear power plant
It creates clean energy as no greenhouse gases are released.
However the area could suffer radioactive poisoning if there was a core meltdown.
Why are velocitys hard to measure when there is a red shift?
The distortion of light waves is less as it is not travelling fast so the increase in detected frequency is very small. This is harder to then detect and measure.
How does conservation of energy apply to an elliptical orbit?
KE is released as it travels round. The PE increases as the KE increases.
Keplers 2nd Law
What is the top number next to an element on the periodic table
The mass number = the number of protons and neutrons combined
What is the bottom number next to an element on the periodic table
The Atomic number so the number of protons or the number of electrons
How to derive the decay constant equation:
Use t = T1/2 and N/N0 = 1/2
N/N0 = e^-Yt
Substitute in values
