Nuclear Models and Radioactivity Flashcards
What is Mass number
Number of protons plus neutrons
What is atomic number
number of protons in a nucleus
Consider Co60
27
1. What is the atomic number
2. mass number
3. number of neutrons
4. number of protons
5. number of electrons
- 27
- 60
- 33
- 27
- 27
What is an isotope
atoms with the same number of protons (atomic number) but a different number of neutrons (mass number)
what is an example of isotopes
C12
6
C13
6
C14
6
complete following equation and determine the decay
40 A
B K —-20 Ca + +1e + ?
A:
B:
0
? = V
0
A: 40
B: 21
write nuclear equation of 144, 60 Nd decaying to Ce by alpha decay
Nd 144, 60—-Ce 140, 58 +a 4,2
write equation to show gamma decay of nickel Ni 60, 28
Ni*, 60, 28 —— Ni, 60, 28 +y
why does gamma decay accompany another type of radioactive decay?
gamma decay is the release of excess energy. So, if another type of decay left the nucleus with extra energy, gamma decay will eject it from the nucleus.
In the decay graph…
1. what type of decay is the top half
2. what is the top right-hand corner
3. what is the middle?
- beta minus
- alpha decay
- beta plus
how can someone minimize their exposure to radiation?
-wear protective shielding/ barriers
-limit exposure time
- increase distance away from the radioactive source
what is ionizing radiation
radiation that is charged, causes the removal of electrons from atoms in cells.
will beta and gamma decay get through a thick piece of steel?
beta wont but gamma will
explain the power of each decay
alpha: isn’t too penetrable, absorbed by air, paper or dead skin.
beta: absorbed in 100cm of air or few cm of aluminum
gamma: air has no effect, absorbed in many cm of lead.
what is half -life
the time it takes for half of the radioactive substance to decay
what is alpha decay
when it occurs, an unstable nucleus ejects an alpha particle - 2 protons and 2 neutrons
what is beta plus and minus decay
- a neutron in an unstable nucleus is converted to a proton and an electron and an antineutrino
+ a proton in an unstable nucleus is converted to a neutron and a positron and neutrino. this process cannot occur in isolation as it requires energy
what is gamma decay
an unstable nucleus with excess energy ejects gamma radiation
what is an induced nuclear reaction
fission and fusion
t-99 has a half- life of 6 hours; the initial activity of the sample is 240bq. what is the activity of the sample after one day?
after 24 hours
24/ 6= 4 squared= 16
it will have 4 half lives. inital activty= 240bq
240x 1/16= 15bq
OR 240/2
120/2
60/2
4 half-lives 30/2
= 15
what is nuclear fusion
fusion is the joining of two smaller nuclei into one big nucleus and it is not spontaneous
what is nuclear fission
fission is when a neutron is absorbed into a big nucleus, it splits into 2 smaller nuclei and releases more than 1 neutron
why are alpha particles less penetrating
bigger mass, alpha is slower
why are beta particles more penetrating then alpha
smaller, and quicker
why are gamma particles very penetrating
they have no mass and very fast (speed of light)
types of ionizing radiation
alpha radiation
beta radiation
x-rays
gamma radiation
how does ionizing radiation affect the human body and give an example of its effects
ionizing radiation breaks chemical bonds and damage tissue structure.
it can lead to cell mutations causing cancer, kill cells, effect cell function.
what is a chain reaction
when a neutron is absorbed by a nucleus causing it to split into 2 more neutrons are released during the fission process. those neutrons then enter more nuclei allowing the, to undergo fission, which releases more neutrons, and it keeps going.
explain function of control rods
control rods are raised and lowered to control the amounts of fission reactions as they stop the fission neutrons from moving through the power station
explain function of fuel rods
cylinders that contain the uranium fuel pellets for fusion
moderator
slows down the reaction neutrons to sustain chain reaction
shield
absorbs ionizing radiation to stop it from going into the environment
coolant
enters reactor and heated by energy released, then transfers energy to 2nd exchange r coolant in heat exchanger
spontaneous fission
occurs without a neutron entering it
what is the strong nuclear force
a strong force that is short ranged, is independent of charge and holds the atom together.
what is the amount of damage caused by radiation depend on
- the type of radiation
- the amount of radiation
- the energy of the particles
- the material that is irradiated
what is required for nuclear fusion to occur
- nuclei need to be close together so the strong force is working, there is large pressure, and the kinetic energies need to be high/ very hot
advantages of nuclear fission
energy efficient fuel, alot of fuel, electiricty can be continously produced, no carbon dioxide emmisions.
disadvantages of nuclear fission
risk of meltdown or other accident, transporting and storing nuclear fuel, disposal and storage of nuclear waste, cost of building and maintaining a facility is initially high.
what is a gamma photon
electromagnetic radiation
do nuclear revision sheet
