Chapter 21 Test Review Flashcards
The half-life of cobalt-70 is 5.3 years. How much of a 1.000 mg sample of cobalt-60 is left after 15.9 years?
A1=1.000x0.5^15.9/5.3
A1=0.125 mg
Tritium a radioactive isotope of hydrogen has a half-life of 12.3 years. If you begin with 1.5mg of this isotope, how many mg remain after 49.2 years?
A1=1.5x0.5^49.2/12.3
A1=.09 mg
Gallium citrate containing the radioactive isotope gallium-67 is used medically as a tumor seeming agent. It has a half life of 77.9 hrs. How much time is needed for a sample of gallium citrate to decay to 10% of its original activity?
1/10=0.5^T/77.9
Log (1/10/.5)= T/77.9
T=259 hrs
Technetium-99 a gamma ray emitter is used in medical imaging. A sample of this isotope emits 3.28x10^5 photon/s. After 1.0 hrs the gamma ray emitter has dropped to 2.9x10^5 photons/s. Calculate the half life of technetium-99?
Log(2.9x10^5/3.28x10^5)/Log0.5=1.0/t
t1/2= 5.6 hours
Radium decaying by alpha emission
Radon+4He2= 226 Ra
Carbon-14 decay by beta emission
14carbon6= 0e-1+14N
Xe decays by positron emission
118xe=0e1+177I53
Magic Numbers
Protons: 2,8,20,28,52,82
Neutrons: 2,8,28,50, 82, 126
Most elements found using fission are…
Radioactive
Fusion products are generally…
NOT radioactive
Alpha particle
4He2
Beta Particle
0e-1 (neutron rich)
Position particle
0e1 same as electron opposite charge
Neutron poor
Electron capture
0e-1 neutron poor
What causes fission?
A SLOW moving nêutron striking a nucleus
What are the 3 stable isotopes of Uranium?
Uranium-234
Uranium-235
Uranium-238
All have the same number of protons but different number of neutrons
Which Nuclei are especially stable? Why? 4He2, 40Ca20, 98Tc43
He and Ca are the especially stable nuclei because they contain TWO even numbers
As the number of protons increases…
The repulsive force also increases
All atoms with an atomic number greater than 83 are…
Radioactive
Unstable nuclei are caused by…
Having too many or too few neutrons
A nucleus becomes stable by …
Emitting radiation through nuclear reactions
A nuclear reaction…
Changes the identity of a nucleus
During transmutation
Charge and mass will be conserved
Alpha penetration
Ability is low, stopped by paper, and dangerous if ingested
Beta penetration
Ability is medium and is stopped by clothing
Gamma penetration
Ability is high; and is the mos dangerous to the body
Transmutation types include…
Natural decay, k-emission, fission, and fusion
If there is only ONE reactant
Alpha, Beta, or position emission
Decay series…
Is a series of decay steps a parent nuclide takes to become a stable daughter nuclide
Nuclear fission
Nucleus splits into 2+ fragments and release energy
Controlled chain
Can be harnessed as nuclear energy
Moderator
Material that slows down neutrons and speeds up fission (water, and graphite)
Fuel rods
Contains the radioactive material that fissions and super heats the water
Control rods
Absorb excess neutrons and keeps them from passing through (boron and cadmium)
Containment vessels
Sheiks the radiation from escaping into the environment
Cooling tower
Allows excess heat from the heated water to cool down
Spent fuel rods
Kept on site in pools until stored in dry casks
Nuclear Power PROS:
- more power
- non-air polluting
- efficient energy
Nuclear power CONS:
- radioactive waste
- radioactive disposal
- meltdown
- 60-70 year operational period
When uranium decays into lead, lead is considered…
The daughter nuclei
In order to use radiometric dating, scientists need to…
Measure the rate that radioactive elements decay
For scientists to dat rocks, scientists…
Measure the ratio of U to Pb
When uranium decays into lead, uranium is considered…
The parent atom
Scientists date the age of the earth by…
Radiometric dating using radioisotopes found in rocks
The rate of a parent atom decaying into a daughter atom is a …
Constant
When 50% of the parent atoms become daughters this is called…
Half-Life
What subatomic particle is necessary to start and keep a fission Chain reaction going
Neutron
Nuclear Fusion
The process in which LIGHT nuclei combine at extremely high temperatures, forming heavier nuclei, and releasing energy
Stars are powered by….
Nuclear fusion
Deuterium and tritium are isotopes of ….
Hydrogen
Fusion ADVANTAGES:
-great weapon
-abundance of fuel
-can make new elements
Fusion DISADVANTAGES:
- not able to produce enough energy to sustain the reaction
Background radiation
The radiation that arises naturally from cosmic rays and from radioisotopes in soil, rocks, food, and air
Harmful radiation
Prolonged
Genetically mutate or destroy cells
Can cause radiation sickness, hair loss, and cancers
High doses: can cause death within a couple days or weeks
To protect yourself from radiation…
Limit exposure, clothing, distance, and time of exposure
Radioactive decay application
Tells us how old rocks and artifacts are; carbon-14 is good for dating specimens
Uses in medicine
Tracers to diagnose a disease
Can be used to treat cancer
PET scans for brains
Uses in food and technology
Irrigation roots
Sanitize good
Space exploration and powering of submarine
Water reactor. How does it work?
A nuclear reacted heats water and prices steam inside the reactor vessel. Water is then pumped through the reactor core and heated by fission. Pipes then feed the steam directly into the turbine to produce electricity
The Band Of Stability
The band of stability represent the area where stable, non-radioactive isotopes exist based on their ratio of neutrons to protons
Geiger muller
The GN counter can detect all kinds of radiation such as alpha, gamma, and beta rays
Scintillation counter
Detects only ionizing radiations
Different types of reactors
- pressurized water reactor
- boiling water reactor
- advanced gas-cooled reactor
- light water graphite moderated reactor
-fast neutron reactor
-operable nuclear power plants
Free radical molecule
An atom or like how containing one or more unpaired electrons
