[CHEM] Unit 16 - Nuclear Chemistry Flashcards
For (natural) radioactive decay to occur, nuclei need to be: stable/unstable
Unstable
T/F: Nuclei with long half-lives undergo decay quickly and are the least stable
F: Nuclei with short half-lives undergo decay quickly and are the least stable
If an element has an atomic number equal to or more than 83, what does that mean?
It is ustable
What type of emissions are negative?
Beta
What type of emissions are positive?
Alpha, positrons, protons
What type of emissions are neutral?
Neutrons, gamma
What are the symbols for alpha particles?
Greek letter A
or
He
How are alpha particles ranked in terms of penetrating power?
They have the lowest power
How are alpha particles ranked in terms of ionizing potential?
They have the greatest potential
What mass and charge do alpha particles have?
Mass: 4
Charge: +2
What is an alpha particle?
A helium nuclei
What are the symbols for beta particles?
Greek letter B
or
e
What are beta particles?
High-speed electrons
How are beta particles ranked in terms of penetrating power?
They are in the middle
How are beta particles ranked in terms of ionizing potential?
They are in the middle
What mass and charge do beta particles have?
Mass: 0
Charge: -1
T/F: Gamma is a particle
F: Gamma is a ray
What is the symbol for gamma rays?
Y
What mass and charge do gamma rays have?
Mass: 0
Charge: 0
What are gamma rays?
Essentially high-energy xrays
How are gamma rays ranked in terms of penetrating power?
They have the greatest power
How are gamma rays ranked in terms of ionizing potential?
They have the lowest potential
What is the symbol for neutron particles?
lowercase n
What mass and charge do neutrons have?
Mass: 1
Charge: 0
What are the symbols for positrons?
Greek letter B
or
e+
What are positrons?
Positive electrons (antimatter)
What mass and charge do positrons have?
Mass: 0
Charge: +1
What are protons?
Hydrogen nucleuses
What is the symbol for protons?
P
What mass and charge do protons have?
Mass: 1
Charge: +1
T/F: In a decay reaction, the mass and atomic numbers on both sides must add up
T
Natural transmutations have 1/2 reactants
1
Artificial transmutations have 1/2 reactants
ALWAYS 2
T/F: Artificial transmutation reactions can have 1 product
T
How does one cause an artificial transmutation?
Bombard a nucleus with a small particle, causing it to change and produce an isotope
T/F: The small particles used in artificial transmutations can have small amounts of energy
F: They must have high amounts of energy to not bounce off the positive nucleus
What is an example of a tracer and what are they used for?
Ex: barium
Uses: GI tract, agriculture, factories
What is used for dating organic material and how is it used?
C-14
The amounts of C-14 are compared to the amounts of C-12
What is used for dating inorganic material and how is it used?
Uranium-238
Amount of U-238 vs Pb-206
What can Tc-99 be used for?
Diagnosing cancer
What can Co-60 be used for?
Treating cancer
T/F: I-131 can be used to treat and diagnose liver cancers
F: it is used to treat and diagnose thyroid cancers
What is food irradiation used for?
Killing bacteria, yeast, mold, etc on food
T/F: There are factors that can affect half life
F: half-life can never be changed
In a fusion/fission reaction, what is the change in mass known as?
Mass defect
What is fusion?
Two or more small nuclei (usually H) combine to form a larger one (usually He)
Fusion releases a lot/a little energy
A lot
Where can fusion reactions be found?
On the Sun
What is the one condition for using fusion in bombs?
Fission has to start it
What are the benefits of fusion?
- Makes the most energy
- No radioactive waste
What are the negatives of fusion?
Needs extremely high temperature and pressure
What is fission?
A large nucleus splits into medium-sized nuclei
What does a fission reaction look like?
Neutrons + U –> Kr/Ba + neutrons + energy
T/F: Fission makes more energy than fusion
F
T/F: Fission is a chain reaction
T
What is fission used for?
- Bombs (uncontrolled)
- Power plants (controlled)
What are the benefits of fission?
- No consumption of fossil fuels
- Less pollution
- More energy vs chemical reactions
What are the negatives of fission?
It produces long-lasting radioactive waste
What does a control rod do and what are some examples?
Used to absorb/remove neutrons to slow down fission
Ex: boron, cadmium
What does a moderator do and what are some examples?
Slows down neutrons so that they can be captured
Ex: water, heavy water, graphite, beryllium
What is heavy water?
Basically water but with different H isotopes like deuterium
What is shielding (in a nuclear power plant)?
It is a steel and concrete layer (separate layers) that prevents leaks
What does a coolant do and what are some examples?
Controls temperature
Ex: Water, heavy water, molten sodium/lithium
What does a fusion reaction look like?
H + H –> He + energy
How do you determine what is left of an isotope if given the half-life and amount of time passed?
1) Divide the time passed by the half-life
2) Divide 1 by however many half-lives passed
3) Multiply that by the given mass
How do you determine how long it takes for an isotope to decay if given the half-life, starting mass and end mass?
1) Divide the starting mass by 1/2 until you reach the end mass
2) How many arrows = amount of half-lives passed
3) Multiply amount of half-lives by half-live #
How do you determine a half-live if given the amount of time, starting mass and end mass?
1) Divide the starting mass by 1/2 until you get end mass
2) How many arrows = how many half-lives
3) Divide amount of time given by # of arrows
How do you get the starting amount if given the half-life, amount of time, and end mass?
1) Determine # of half-lives passed by dividing the time passed by the length of half-life
2) Number of half-lives passed = amount of times you need to double the end mass
