Chemistry - chapter 17
Can nuclear fusion be used to generate electricity? What are the advantages of fusion for electricity generation? What are the problems with fusion?
Fusion is not currently used for electricity generation. Fusion is an excellent candidate for electricity generation because it provides 10 times more energy per gram of fuel than fission reactions and the products of the reaction are not radioactive, However due to the extreme temperatures needed to initiate fusion reactions there is no known material that can withstand the temperature
What is gamma radiation? What is the symbol for a gamma ray?
Gamma radiation is a type of electromagentic radiation that is essentially a high-energy photon. The gamma particle is symbolized by 0/0 y
Explain how radiation can cause genetic defects. Has this ever been observed in laboratory animals? In humans?
Genetic defects in offspring could occur if radiation damaged reproductive cells. The defects have been observed in lab animals but not humans.
What happens to an atom when it emits a beta particle?
When an atom emits a beta particle, a neutron in the nucleus is converted to a proton. As a result, the atomic number increases by 1 while the atomic mass remains constant.
What happens to an atom when it emits a positron?
When an atom emits a positron, it converts a proton to a neutron, which converts it into an atom of the next lighter element ( z decreases by 1, while A remains constant )
What happens to an atom when it emits an alpha particle?
When an atom emits an alpha particle, the atomic number decreases by 2 and the atomic mass by 4
What happens to the carbon-14 in a living organism when it dies? How can this be used to establish how long ago the organism died?
When an organism dies, it no longer uptakes carbon-14, therefor the amount of carbon-14 starts to decay at the rate equal to the half-life of carbon-14 by measuring how much carbon-14 remains in an organism, you can use the half life to determine how long it took the carbon-14 to decay to the current level.
Explain what each symbol in the notation represents A/Z X
X= chemical symbol, used to identify element Z= atomic number, the number of protons in the nucleus; determines the identity of the element A= atomic mass, the sum of the number of protons and the number of neutrons in the nucleus
What is critical mass?
a critical mass is the minimum amount of uranium needed to create a chain reaction
Explain the medical use of isotope scanning.
Isotope scanning is a method used to diagnose different disease based on the use of radioactive isotopes and their ability to target different organs and tissues The radioactive isotopes are detected with either photographic film or scintillation counter
What are some sources of natural radioactivity?
Natural sources of radioactivity include some naturally occurring radioactive atoms in soil and minerals ( uranium, radium ) in the food that we eat, and radiation from space that makes its way through the atmosphere
What is nuclear fission? How and by whom was it discovered?
Nuclear fission is the process of splitting a nucleus into smaller elements
What is nuclear fusion?
Nuclear fusion is the process of two lighter elements coming together to form a heavier element along with release of a large amount of energy
What is positron emission? What is the symbol for a positron?
Positron emission occurs during the conversion of a proton in the nucleus to a neutron. The positron particle emitted has the same mass as an electron, but it has a positive charge. The positron is symbolized by 0/+1 e
How do the ionizing power and penetrating power of positrons compare to other types of radiation?
Positrons have a similar ionizing power and penetrating power as beta particles, which are intermediate in comparison with other radioactive particles
Explain how radiation can increase cancer risk.
Radiation can increase the risk of cancer because it can damage DNA which can cause cells to grow abnormally
How does radiation affect the molecules within living organisms?
Radiation can ionize molecules in living organisms
What is radioactivity? What does it mean for an atom to be radioactive?
Radioactivity is the emission of tiny, invisible ( to the human eye ) particles by the nuclei of certain atoms. A radioactive atom will spontaneously emit these tiny, invisible particles.
What happens to an atom when it emits a gamma ray?
Since a gamma ray has no charge and no mass, it does not change the mass of atomic number of an atom. Gamma rays provide a release of energy from a nucleus and are usually emitted in conjunction with other types of radiation.
Explain the purpose of the control rods in a nuclear reactor core. How do they work?
The control rods serve to regulate the rate of the nuclear fission reaction in the reactor core so that the temperature is maintained at a desired level.
What are the main advantages and problems associated with nuclear electricity generation?
The main benefits of nuclear electricity generation are that it requires very little fuel and doesn't create air pollution or greenhouse gases. The problem associated with nuclear power is the disposal of radioactive waste.
What is the main unit of radiation exposure? How much radiation is the average U.S. resident exposed to per year?
The main unit of radiation is the roentgen equivalent man also known as rem A typical person is exposed to one-third of the rem per year
Why can nuclear fission be used in a bomb? Include a concept of a chain reaction in your explanation?
The nuclear fission reaction is triggered by a neutron colliding with fissionable nuclide, which produces lighter elements and more neutrons. The neutrons produced in the reaction can then collide with other nuclides, producing a chain reaction, which can be used to make a bomb due to the amount of energy
Identify the parent nuclides and the daughter nuclides in the nuclides equation. Which kind of radioactive decay is involved? 231/91 Pa > 227/89 Ac + 4/2 He
The parent nuclide is the reactant 231/91 Pa the daughter nuclides are the products 227/89 Ac and 4/2 He. The equation represents alpha emission
How do we know that carbon-14 ( or radiocarbon ) dating is accurate? What is the age limit for which carbon-14 is useful?
carbon-14 has been proven accurate by measuring the levels of carbon-14 in objects that are of known age, proving it is an accurate method.
How do the ionizing power and penetrating power of gamma particles compare to other types of radiation?
gamma rays have low ionizing power and high penetrating power in comparison with other radioactive particles
A 68-mg sample of a radioactive nuclide is administered to a patient to obtain an image of her thyroid. If the nuclide has a half-life of 12 hours, how much of the nuclide remained in the patient after 4.0 days?
4 days x 24 hours/ 1 day x 1 half-life/ 12 hours = 8 half-lives 68>34>17>8.5>4.25>2.125>1.0625>0.531>0.266
What is acute radiation damage to living organisms?
Acute radiation damage results from exposure to large amounts of radiation in a short period of time, thee high levels of radiation kill large numbers of cells, particularly rapidly dividing cells such as those found in the immune system and the intestinal lining
What is alpha radiation? What is the symbol for an alpha particle?
Alpha ( a) radiation occurs when the nucleus emits a particle that contains 2 protons and 2 neutrons. Alpha particles are symbolized by 4/2 He
How is ionizing power and penetrating power of alpha particles compare to other types of radiation?
Alpha particles have a high ionizing power in comparison with other radioactive particles; however they have a very low penetrating power in comparison with the other radioactive particles
What is beta radiation? What is the symbol for a beta particle?
Beta (B) radiation occurs when the nucleus emits an electron. The beta particle is symbolized as 0/-1 e
How does ionizing power and penetrating power of beta particles compare to other types of radiation?
Beta particles have intermediate ionizing power and penetrating power in comparison with other radioactive particles.
Do modern nuclear weapons use fission, fusion, or both? Explain.
Traditional nuclear bombs are of the fission type, however hydrogen bombs are based on fusion.
How is radioactivity used to treat cancer?
Cancer cells are known for their ability ti grow and divide, radiation is effective in killing rapidly growing cells so used to kill cancer cells. Some healthy cells are also killed causing patients to suffer from radiation sickness
What is the source of carbon-14 in our environment? Why do all living organisms contain a uniform amount of carbon-14?
Carbon-14 comes from the reaction of atomic N with the neutrons in the upper atmosphere Carbon- 14 converted into carbon dioxide and then into plant material during photosynthesis. Since animals ingest plant material, all living organisms contain a residual amount of carbon-14 The carbon-14 level is continuous as all living organisms continually ingest new amounts of carbon-14
Describe the outcomes of radiation exposure at different doses ( in rem )
20-100 decreased white blood cell count and possible increase in cancer risk 100-400 radiation sickness, skin lesicns in cancer risk 500 death
Fill in the blanks in the particle decay series. 225/88 Ra > 225/89 Ac + ? 225/88 Ac > ? + 4/2 He ? > 217/85 At > + 4/2 He 217/85 At > ? + 4/2 He
225/88 Ra > 225/89 Ac + 0/-1 e 225/89 Ac > 221/87 Fr + 4/2 He 221/87 Fr > 217/85 At +4/2 He 217/85 At > 213/83 Bi + 4/2 He
What is a nuclear equation? What does it mean for a nuclear equation to be balanced?
A nuclear equation represents nuclear processes such as radioactivity. For a nuclear equation to be balanced the sum of the atomic numbers on both sides of the equation must be equal
Explain the concept of half-life.
The half-life of a radioactive nuclide is the time it will take for one-half of the original parent nuclides to undergo decay. The half-life can be used to determine radioactive decay rates
How can nuclear fission generate electricity?
The heat generated by a controlled nuclear fission reaction is used to boil water, the steam produced turns turbines which generate electricity
