chapter 13 PS HW
What exactly is a chain reaction?
A reaction in which the products of one reaction initiate subsequent reactions
What is a rem?
A rem is a unit for measuring radiation exposure.A rem is a unit for measuring radiation exposure.
What change in atomic number occurs when a nucleus emits an alpha particle? What change occurs when the nucleus emits a beta particle?
Alpha emission decreases atomic number by two, while beta emission increases it by one.
Which type of radiation—alpha, beta, or gamma—results in the greatest change in mass number? Which results in the greatest change in atomic number?
Alpha radiation results in the greatest change of mass number and atomic number.
What type(s) of radiation is/are emitted by the nuclei of radioactive elements?
Both fast-flying subatomic particles and electromagnetic
Classify each of the following characteristics as related to fusion, fission, or both.
Fission only: used in nuclear power plants, byproducts have long half-lives Fusion only: occurs on the sun, needs very high temperatures fission and fusion: releases lots of energy
Which of the following statements about fusion is true?
Fusion reactions have no critical-mass requirement.
What happens to a nitrogen atom that captures a neutron in the atmosphere?
It becomes a carbon-14 atom.
Is a chain reaction more likely to occur in two separate pieces of uranium-235 or in the same two pieces stuck together?
It's more likely in two pieces stuck together.
Is the mass of an atomic nucleus greater or less than the sum of the masses of the nucleons composing it? Why don't the nucleon masses add up to the total nuclear mass?
Less. The individual nucleons have greater mass when separated from the nucleus. This additional mass is a result of the energy of separation.
What role do neutrons play in the atomic nucleus?
Neutrons are a nuclear cement holding the nucleus together.
What evidence supports the contention that the strong nuclear force is stronger than the electrical interaction at short inter-nuclear distances?
Protons are able to exist side-by-side within an atomic nucleus.
Is radioactivity on Earth something relatively new? Explain.
Radioactivity has existed for the entire life of the Earth
What is a common source of radiation arising from Earth?
Radon-222
The element uranium (U, atomic no. = 92) often has 146 (or more) neutrons but it will still undergo radioactive decay. Which statement might best describe why?
The attractive force of the nucleons has a limited range.The isolated neutron is not stable and will undergo spontaneous transformation into a proton and an electron. both a and b
Why doesn't the repulsive electric force of protons in the atomic nucleus cause the protons to fly apart?
The attractive strong nuclear force is stronger than the repulsive electric force.
Why is the carbon-14 dating not accurate for estimating the age of materials more than 50,000 years old?Why is the carbon-14 dating not accurate for estimating the age of materials more than 50,000 years old?
The concentration of carbon-14 in a body after 50,000 years is too low.
Which of the following statements about chain reactions is true?
The key requirement for a chain reaction is that more neutrons are produced than are absorbed.
How does the mass of a pair of atoms that have fused compare to the sum of their masses before fusion?
The mass after fusion is less than the sum of their masses before fusion.
Which of the following statements about fusion is the most accurate?
The mass of the products is less than the mass of the reactants.
Why might the following nuclear reaction not be very good for energy production in a fission reactor?23592U→13556Ba+9936Kr+192235U→56135Ba+3699Kr+1 neutron
The material only produces one neutron so the chain reaction will not be very efficient.
Which of the following statements best describes why a large nucleus is more likely to undergo radioactive decay?
The nuclear forces are not as strong as the repulsive electrical forces between nucleons.
What is meant by the half-life of a radioactive sample?
The time it takes for half of a radioactive sample to decay.
What is the term for the changing of one element into another?
Transmutation
Why would you expect alpha particles to be less able to penetrate materials than beta particles of the same kinetic energy?
Two of the above answers are reasonable.
Why is lead found in all deposits of uranium ores?
Uranium radioactively decays to lead.
Plants contain a little carbon-14, but why do humans also contain carbon-14?
We eat plants containing carbon-14.
Which of the following statements about radiation is true?
Your body contains a number of radioactive isotopes.
Which of the beams is due to a high energy electron?
a
Which of the beams is actually composed of particles?
a and c
If three samples have the half-lives listed below, which is the most radioactive?
a sample with a half-life of 20 minutes
Which type of radiation is being emitted in the following incomplete nuclear equation:21884Po→21482Pb+??
alpha
When 21884Po84218Po emits a beta particle, it transforms into a new element. What are the atomic number and atomic mass of this new element?
atomic number = 85; atomic mass = 218
When 22688Ra88226Ra decays by emitting an alpha particle, what is the atomic number of the resulting nucleus? What is the resulting atomic mass?
atomic number = 86; atomic mass = 222
The image below shows a beam of radiation passing between two electrically charged plates.Which of the beams is due to an energetic light wave?
b
Which of the following sources of radiation provides most of our yearly exposure?
background radiation
Which of the beams is due to a positively charged helium nucleus?
c
Which process would release energy from gold: fission or fusion?
fission
Which process would release energy from carbon: fission or fusion?
fusion
Which type of radiation from cosmic sources predominates on the inside of a high-flying commercial airplane: alpha, beta, or gamma?
gammma
The alpha particle has twice the electric charge of the beta particle but deflects less than the beta in a magnetic field because it
has much more inertia
Why might the following nuclear reaction not be very good for energy production in a fission reactor?5626Fe→2914Si+2412Mg+32656Fe→1429Si+1224Mg+3 neutrons
he reactants are too small to obtain energy from the missing mass due to strong nuclear force.
In what form is the most energy released by atomic transmutation?
kinetic energy
Which of the following provides the minimum amount of protection you need to block the following form of radiation?gamma
lead suit
Which process would release energy from iron: fission or fusion?
neither fission nor fusion
uranium-238 absorbs a neutron and then emits a beta particle. what is the resulting nucleus?
neptunium-239
Suppose 2 kg of a material has a half-life of 1 day. After how long will NONE of the material remain?
never
If carbon-14 is a beta emitter, what is the likely product of radioactive decay?
nitrogen-14
Does a radioactive isotope ever lose its radioactivity?
no
Is it at all possible for a hydrogen nucleus to emit an alpha particle?
no, because it does not contain enough nucleons
Which of the following nuclear equations correctly describes beta emission?
none
Which of the following statements regarding a nucleon is true in regards to nuclear reactions?
nucleon inside a nucleus has a lower mass than a nucleon outside of the nucleus.
Which of the following provides the minimum amount of protection you need to block the following form of radiation?alpha
sun tan lotion
A friend produces a Geiger counter to check the local background radiation. It ticks. Another friend, who normally fears most that which is understood least, makes an effort to keep away from the region of the Geiger counter and looks to you for advice. What do you say?
the Geiger counter is detecting naturally occurring radiation from your body.
Why is the combination of two protons and two neutrons stable, but two protons and one neutron is not?
there are not enough neutrons to overcome the electrical repulsion of the protons.
Which of the following provides the minimum amount of protection you need to block the following form of radiation?beta
thick leather
A certain radioactive element has a half-life of one hour. If you start with a 1-g sample of the element at noon, how much of this same element will be left at 3:00 PM?
0.125 gram
Suppose the half-life of a material is 10 days. You have one 1 kg of the material today. How much of the material would you have after 10 days and 20 days, respectively?
0.5 kg after 10 days, and 0.25 kg after 20 days
The half-life of carbon-14 is 5730 years. A sample is found to have one-eighth the original amount of carbon-14 in it. How old is the sample?
17,200 years
Complete the following nuclear equation:21083Bi→??+0−1e
21084Po
Complete the following nuclear equation:??→21885At+0−1e??→85218At+−10e
21884Po
Which of the following nuclei is likely to release energy when undergoing nuclear fusion?
21H12H (deuterium)
Complete the following nuclear equation: ??→22286Rn+42He
22688Ra
If Uranium-234 decays via alpha emission, what is the likely product of radioactive decay? (U, atomic no. = 92)
23090Th
Which of the following nuclei could be used in a nuclear fission power plant?
235 92U 92235U (uranium-235)
Complete the following nuclear equation:21083Bi→20681Tl+??
42He
If a material has a half-life of 24 hours, how long do you have to wait until the amount of radioisotope is 1/4 its original amount?
48 hours
A material has a half-life of 1 day. If 2 kg of this material is available today, how much of it was available yesterday, and how much the day before?
4kg yesterday, and 8 kg the day before