Nuclear Chemistry
Beta decay
Beta decay is when a radioisotope breaks down to release beta particles
Nuclear reactions
Occur when the nucleus of an atom changes Atoms are changed Involve protons, neutrons, and electrons Associated with large energy changes
How do physical sunscreens work?
Physical sunscreens work by reflecting UV radiation away from the skin.
Positron emission
Positron emission is when a radioisotope breaks down to release a positron
What is a common source of gamma radiation?
Radiation therapy for cancer, as well as in nuclear power plants and other industrial settings
What are some examples of radioactive materials that alpha particles have encountered?
Radon gas. Exposure to high levels of radon gas over long periods of time can increase the risk of lung cancer.
U-238 with Lead-206
Rock dating
Smallest remaining %
Shortest half-life Smallest mass
Alpha particle
Similar to a helium nuclei Has a mass of 4 amu and a charge of +2
Gamma radiation
Similar to a high energy x-ray Has a mass of 0 amu and a charge of 0
Beta particle
Similar to a high speed electron Has a mass of 0 amu and a charge of +1
What is an example of a natural source of beta particles?
Strontium-90. This can accumulate in the bones and potentially increase the risk of bone cancer.
Penetrating power
The ability of a particle. The penetration of alpha, beta, and gamma through three materials
What is Americium-241 (Alpha decay) used for?
Americium-241 is commonly found in household smoke detectors, where it ionizes the air inside the detector and allows for the detection of smoke particles.
Transmutation
The changing (converting) of one atom to another Transmutation of an atom involves changing the contents of its nucleus During a transmutation, particles are absorbed and/ or released by the nucleus
Nucleus
The inner core of an atom Contains protons and neutrons
Compare/contrast electron and beta particle
The main difference between an electron and a beta particle is that the electron is negatively charged while the beta particle can either be charged or not.
Original Mass
The mass of a sample given at the start of a decay
Remaining Mass
The mass of the sample after a given time of a decay
Nuclear fusion has the potential to be a highly efficient and clean source of energy, as it
produces no greenhouse gases or other harmful emissions.
What is the fraction remaining after 4 half-lives?
1-16
Determine the half-life of krypton-92 if only 6.0 milligrams of an original 96.0-milligram sample remains unchanged after 7.36 seconds.
1.84 seconds
What fraction of Au-198 will remain unchanged after 4 half-life periods?
1/16
What fraction is remaining and how many half-lives have passed if a 100g substance now has 12.5g left of radioactivity?
1/8 radioactive and 3 half-lives
Selenium-83 has a half life of 25 minutes. How many minutes would it take for a 20 milligram sample to decay and only have 1.25 milligrams of it remaining?
100 minutes
Explain what E=mc^2 means
This states that energy (E) is equal to mass (m) times the speed of light squared (c^2).
Compare / contrast nuclear fusion and fission
Both release a great amount of energy, however, nuclear fusion is the process of combining two atomic nuclei to form a heavier nucleus. Nuclear fission is the process of splitting an atomic nucleus into two or more smaller nuclei.
If 10 mg of iodine 131 is given to a patient, how much is left after 24 days? The half-life of iodine-131 is 8 days.
1.25mg
What the fraction remaining after one half-life?
1/2
The half life of a substance is the time it takes for a substance to become
1/2 radioactive
What fraction of 19 Ne will remain unchanged after 86 seconds?
1/32
What is the fraction remaining after 2 half-lives?
1/4
After two half lives a substance is
1/4 radioactive
After the third half-life, how much of the sample is left?
1/8
The half-life of a certain isotope is 1 year. If you have 40 grams of the isotope, how much will remain after 3 years?
1/8 or 12.5%
The half-life of Zn-71 is 2.4 minutes. If one had 100.0 g at the beginning, how many grams would be left after 7.2 minutes has elapsed
12.5g
The half-life of Zn-71 is 2.4 minutes. If one had 100.0 g at the beginning, how many grams would be left after 7.2 minutes has elapsed?
12.5g
If a 90-g sample of radon-226 is placed in a safe container, how many grams of it will remain unchanged 4800 years later.
13.75 g
How many reactants in artificial transmutation?
2
If one-fourth of the carbon-14 is remaining then how many half-lives have passed?
2
What is the half-life of an unknown radioisotope if it takes 12 years for the radioisotope to undergo 5 half-life periods?
2.4 years
Barium-122 has a half-life of 2 minutes. A fresh sample weighing 80 g was obtained. If it takes 10 minutes to set up an experiment using barium-122, how much barium-122 will be left when the experiment begins?
2.5g
Finish the decay: 226 88 Ra -
222 86 Rn + 4 2 H
How many half-lives have passed if 1/8 of a substance remains radioactive?
3
What is the Half Life of this isotope?
3 days
An unknown quantity of cesium-137 was left behind in a facility 90.6 years ago. How many half-life periods of decay would the sample have gone through since then?
3 half life periods
Fermium-253 has a half-life of 0.334 seconds. A radioactive sample is considered to be completely decayed after 10 half-lives. How much time will elapse for this sample to be considered gone?
3.34 seconds
How long will it take for potassium-42 to decay from 100 g to 12.5 g?
37.08 hours
Determine the number of half-life periods it takes for a 40-gram sample of gold-197 to decay to just 1.25 grams.
5 half-life periods
You have 100 grams of radioactive C-14. The half life of C-14 is 5730 years. How many grams are left after 1 half life?
50 grams
After 22,800 years, approximately what percentage of the original carbon-14 remains?
6.25%
Solve this equation for beta decay.6 14 C = ___ + -1 0 e
7 14 N
What is 704 million years in scientific notation?
7.04 x 10^8 years
Approximately how long will it take for a radioactive 42 (mass number) K to undergo 6 half-life periods?
74.16 hours
What is the half-life of iodine-131?
8 days
Solve this equation for alpha decay. 85 209At = ___ + 2 4He
83 205Bi
After 6 half-life periods, 15 grams of an unknown radioisotope remains. What was the original mass of the unknown radioisotope?
Double the given remaining mass 6 times going backward. 960 g
Nuclear Chemistry Particles
During a nuclear reaction, atomic particles are absorbed and released
Nuclear chemistry
The study of changes that occur in atomic nuclei
What is an example of nuclear fusion?
The sun, where hydrogen atoms combine to form helium and release energy in the process.
What is Uranium-238 (Alpha decay) used for?
U-238 is the most abundant isotope of uranium, making up about 99.28% of natural uranium. Unlike U-235, it is not fissile, but can be converted into plutonium-239, which is fissile, through a process called breeding.
Why is half-life important?
Understanding the half-life of common radioisotopes is essential for various applications, from geological dating to medical treatments. By knowing their decay rates, we can harness their potential for scientific and practical purposes while ensuring safety and accurate measurements.
Radioisotopes
Unstable forms of elements that undergo natural radioactive decay, a spontaneous process that doesn't require human intervention
The strong nuclear forces holding the nucleus together result in
a large energy release when these forces are disrupted
Which particle has the highest IONIZING power?
alpha
Which particle has the lowest penetrating power?
alpha
A helium nucleus with two protons and two neutrons is called a(n) ____
alpha particle
Which form of nuclear decay has the lowest penetrating power and highest ionizing power?
alpha particle
Positrons are the _________ counterpart of electrons, possessing the same mass but with a positive charge
antimatter
Radioisotope
any radioactive or unstable isotope of an element. radioisotopes spontaneously decay
According to Table N, what is the decay mode for Carbon-14?
beta
Which particle is the same as an electron?
beta
Which particle is also called an electron?
beta particle
Gamma rays are part of the
electromagnetic spectrum and can be produced by natural sources such as the sun
Which subatomic particle is the same as a beta particle?
electron
Chemical reactions involve only the changes in the arrangement of ___________ and the formation or breaking of chemical bonds
electrons
When nuclei decay, massive amounts of __________ is released.
energy
These nuclear chemistry particles are discussed
first
Understanding these principals is crucial to understanding the
fundamental nature of matter and energy in the universe.
Which form of nuclear decay has the highest penetrating power and lowest ionizing power?
gamma
Which particle has the highest penetrating power?
gamma
Which particle has the lowest IONIZING power?
gamma
Which particle has the lowest mass?
gamma has the lowest mass
A benefit of using the radioisotope Uranium is
geological dating
Use Table O to:
get and compare mass and charge of particles get the correct particle notation when writing a nuclear equation
What is nuclear fission used for?
This process is used in nuclear power plants to generate electricity by harnessing the energy released when uranium atoms are split.
Use of Carbon-14 alone
Tracer for chemical reactions
Why is transmutation important?
Transmutation is important in nuclear reactions and can be used to create new isotopes for medicine.
True or False: Chemical sunscreens are typically absorbed into the skin and may be less visible on the skin, while physical sunscreens are often more visible and may leave a white cast on the skin.
True
True or False: Fusion joins light nuclei to form a heavier nucleus with a release of energy greater than that of fission
True
Describes what happens during a nuclear fusion reaction
Two nuclei joined to create a slightly larger nucleus Energy is converted from mass (or mass to energy) Tons of nuclear energy are released Energy released is much greater than that of fission Fusion produces no nuclear waste, unlike fission High temperature and pressure are required for fusion High temperature and pressure are necessary to overcome the repelling of the two positive nuclei that are to be joined (fused) together
U-235 is split into
Krypton-92 (Kr-92) and Barium-141 (Ba-141), as well as additional neutrons that can cause further fission reactions
Describe how alpha particles can cause transmutation
The alpha particle can be absorbed by the nucleus, causing it to become unstable and emit radiation. This radiation can result in the ejection of a proton, which changes the identity of the element.
What is half-life?
The amount of time it takes for half the nuclei in a sample of the isotope to decay
What is one example of nuclear fission in action?
The an nuclear bomb dropped on Hiroshima during WWII
What are the fundamental principles that govern all nuclear reactions?
The conservation laws of mass number and electrical charge
Tracer
A radioisotope that it used to follow the path of chemical reaction
What is the mass of a beta particle?
0
The half-life of strontium-90 is 25 years. How much strontium-90 will remain after 100 years if the initial amount is 4.0 g?
0.25 g
How many reactants in natural transmutation?
1
Fraction Remaining =
1 / 2^n
C-14 with C-12
Fossilized dating
What is the fraction remaining after 3 half-lives?
1/8
Fraction remaining =
(1/2) ^n
What are the different types of natural transmutation?
Alpha decay, beta decay, and positron emission
Name this high-energy nuclear particle: They are relatively large and heavy, which means that they can be easily absorbed by a thin sheet of paper, clothing, or even the outer layer of skin.
Alpha particle
Compare/contrast alpha and gamma particle in terms of penetrating power and ionizing power
Alpha particles have low penetrating power but high ionizing power, while gamma particles have high penetrating power but low ionizing power. However, they are both very harmful.
Stability of Nucleus:
Depends on Neutrons to Protons Ratio
Which alkaline Earth element has no stable isotope?
Radium
Decays to greatest extent =
Shortest half-life
What is transmutation?
When one element changes to another element
Nuclear wastes are
highly radioactive
Spontaneous reactions can be...
natural reactions
These elements are naturally
radioactive
A benefit of using the radioisotope Iodine is
thyroid disorders
Describe the nuclear process of beta decay
After decay, the mass number stays the same, the protons increase by 1, and the neutrons decrease by 1
If the half-life of uranium-232 is 70 years, how many half-lives will it take for 10 g of it to be reduced to 1.25 g?
3 half-lives
The half life of iodine-131 is 8.040 days. What percentage of an iodine-131 sample will remain after 40.20 days?
3.125%
Fermium-253 has a half-life of 0.334 seconds. A radioactive sample is considered to be completely decayed after 10 half-lives.
3.34 seconds
How many half-lives have passed if 1/16 of a substance remains radioactive?
4
What is the mass of an alpha particle?
4 amu (2 protons, 2 neutrons)
A radioactive isotope has a half-life of 4 years. If you start with 100 grams of the isotope, how much will remain after 4 years?
50
You have 100 grams of radioactive C-14. The half life of C-14 is 5730 years.How many grams are left after 1 half life?
50 grams
Accelerator
A device that moves charged particles to a high speed. Only charged particles (alpha, beta, and positron) can be accelerated
Describe what happens during a nuclear fission reaction
A large fissionable (splittable) nucleus is broken up into smaller nucleus fragments Energy is converted from mass (or mass to energy) Tons of nuclear energy are released Energy released is less than that of a fusion reaction Dangerous nuclear wastes and radiations are also produced
Radioactive decay
A natural process in which unstable atomic nuclei lose energy by emitting radiation in the form of particles or electromagnetic waves.
Compare/contrast positron and beta particle
A positron is the antimatter counterpart of an electron (β⁻). A positron is a positive electron (β⁺)
Describe the nuclear process of alpha decay
After decay, the mass number decreases by 4, the protons decrease by 2, and the neutrons decrease by 2
Describe the nuclear process of positron emission
After decay, the mass number stays the same, the number of protons decrease by 1, and the number of neutrons increase by 1.
What is Carbon-14 (Beta decay) used for?
Carbon-14 is used in radiocarbon dating, a technique employed by archaeologists and geologists to determine the age of organic materials up to about 50,000 years old 14 6 C turns into 14 7 N and Beta
Which radioisotope has the same decay mode and nearly an identical half-life as strontium-90?
Cesium-137
How do chemical sunscreens work?
Chemical sunscreens work by absorbing UV radiation before it can penetrate the skin.
Clean energy
Clean energy sources, such as solar, wind, and hydroelectric power, harness energy from renewable resources.
What is Cobalt-60 (Beta decay) used for?
Cobalt-60 is used as a radiation source in cancer therapy, sterilizing medical equipment, and food irradiation to preserve perishable items and reduce the risk of food borne illnesses.
Why has the caveat come about?
Einstein's famous equation, E=mc^2
What are the downsides of nuclear fusion?
High energy and pressure are needed to overcome repelling nuclei
How is nuclear fusion different from nuclear fission?
In fusion, the product is a larger atomic nucleus.
What is Iodine-131 (Beta decay) used for?
Iodine-131 is used to treat thyroid disorders, including hyperthyroidism and certain types of thyroid cancer. It is also used as a trace in diagnostic tests for thyroid function.
What are the benefits of nuclear fission?
It is used in nuclear power plants to produce energy
What are the downsides of nuclear fission?
It produces dangerous radioactive wastes
What are the benefits of nuclear fusion?
It produces no radioactive waste
Half-life Period (n) =
Length of Time (T) / Half-Life (t) (Table N)
Decays to least extent =
Longest half-life
Greatest remaining %
Longest half-life Greatest mass
How do you differentiate between chemical and nuclear reactions?
Look for changes in the atomic nuclei or the release of high-energy particles (alpha, beta, or positron radiation), which indicate nuclear reactions.
Solving Half-life Problems
Many half-life problems can be solved with little or no setup One or both equations below can be used if a setup is necessary
What is conserved in nuclear reactions (even though there is one caveat)?
Mass and charge only
What is an important caveat, or principle to the conservation laws of mass number and electrical charge?
Mass can be converted to energy during nuclear reactions.
What is another way of saying spontaneous decay?
Natural radioactive decay
Types of Nuclear Reactions
Natural transmutation alpha decay beta decay positron emission Artificial transmutation Fission Fusion
Are gamma rays and neutrons able to be accelerated?
No
Nuclear power
Nuclear power is generated by splitting atoms, usually U-235, in a process called nuclear fission. This process releases an enormous amount of heat energy, which is then converted into electricity.
Nuclear fission (nuclear energy)
Nuclear splits into smaller nuclei Caveat- Mass is lost and converted to energy (e = mc^2)
Nuclear fusion (nuclear energy)
Nuclei join to make a larger nucleus. Mass is converted to energy Energy is more than that of nuclear fission
Chemical reactions
Occur when bonds are broken/formed Atoms are unchanged but rearranged Only involve the transfer of electrons Associated with small energy changes
More information abut these nuclear reactions
The nucleus is positively charged In fusion, two positively charged nuclei must be brought (joined) together. The two positive nuclei will repel; opposites attract, but similar charges repel Extremely high amount of energy and pressure are needed to join two positive nuclei in fusion
Half-life Period of a Decay
The number of times a radioisotope decays by half Ex. A 24-g sample of iodine-131 (or any radioisotope) will decay to 6 g in two half-life periods
Neutron
The particle in the nucleus with no charge Determines the mass number of an atom, and accounts for differences in the atoms of an element
Proton
The positive particle in the nucleus Determines the atomic number (identity) of an element
Nuclear reaction
The process that leads to changes in the nucleus contents of atoms
Fraction Remaining
The ratio of the remaining mass to original mass of a sample after a certain time of a decay
Length of Time of a Decay
The total time it takes for a radioisotope to decay from one mass to another. Ex. A 24-g sample of iodine-131 will decay to 6 g in 16.042 days.
Describe the process of radioactive decay
There is one reactant (the unstable isotope) and two products (a most stable or stable isotope and a radioactive particle)
How do radioisotopes become more stable?
These isotopes release energy during decay, transforming into more stable elements
Where are artificial transmutations conducted?
They are conducted in a particle accelerator
What does the conservation laws of mass number and electrical charge state?
They state that mass number and electrical charge are always conserved in any nuclear reaction, whether it's a fusion, fission, or radioactive decay.
Why do nuclear reactions release more energy than chemical reactions?
This is because nuclear reactions involve changes in the atomic nucleus, whereas chemical reactions involve electron rearrangements.
What is Technetium-99m (Beta decay) used for?
This radioisotope is widely used in medical imaging as a tracer, allowing doctors to visualize the internal structure and function of organs and tissues
What is Uranium-235 (Alpha decay) used for?
U-235 is a rare isotope of uranium, constituting only about 0.72% of natural uranium. It is fissile, meaning that it can undergo nuclear fission when bombarded with neutrons. This property makes U-235 the primary fuel for nuclear reactors and nuclear weapons.
Separation of Particles:
Using Electric Field As particles are released from a radioactive source: Negative particles (β-) will deflect toward the Positive plate(+) Positive particles (α+) will deflect toward the negative plate(+) Particles with no charge (γ) will be unaffected by the electric field and go straight through.
Natural transmutation
When a single unstable radioactive nucleus spontaneously decays (breaks down) to another nucleus
Artificial transmutation
When a stable non-radioactive nucleus is bombarded (hit) with a particle to produce an unstable (radioactive) nucleus
What is nuclear fission?
When the nucleus of an atom is split to form two smaller nuclei
What is nuclear fusion?
When two nuclei combine to form one larget nuclei
Chemical sunscreens contain _________ compounds, such as avobenzone and octinoxate, that absorb UV radiation and convert it to heat, which is then released from the skin.
organic
Objects that can stop each radiation is used to compare
penetrating powers
Any change to the number of protons and/ or neutrons of an atom will
change (transmute) the atom to a different atom
The nucleus can undergo many different types of
changes
The bottom number is the
charge
Half-life is
constant. Does not change with a change in temperature, pressure, or quantity.
Nuclear fusion requires extremely high temperatures and pressures, typically those found in the
core of the sun
Geologists use the time it takes for a radioactive isotope to decay to half its original mass called a___________.
half-life
The number of half-life periods must be known or determined in order to solve many
half-life problems.
Which phrase describes a risk of using the radioisotope Co-60 in treating cancer? production of acid rain production of greenhouse gases increased biological exposure increased ozone depletion
increased biological exposure
Decay Mode:
indicates the particle that is emitted by a radioactive nucleus as it decays (breaks down)
Physical sunscreens contain ________ compounds, such as zinc oxide or titanium dioxide, that form a barrier on the skin and reflect UV radiation back into the environment.
inorganic
A small amount of mass can be converted into a
large amount of energy
Wastes and radiations produced from nuclear reactors are highly dangerous to
life on Earth
The top number is the _________ number
mass
What is converted to energy in a nuclear reaction?
mass
The energy released during a nuclear reaction is a result of breaking chemical bonds forming chemical bonds mass being converted to energy energy being converted to mass
mass being converted to energy
What is the one caveat about nuclear reactions?
mass is converted to energy
Nuclear energy reactions involve the conversion of
mass to energy
Which subatomic particle has has a mass of 1 and a charge of zero?
neutron
Most elements with atomic number 83 and above have no stable isotopes due to high
neutron-to-proton ratio.
These changes form
new atoms and release energy and radiations.
Billions of times more energy is produced in ________ reactions than in any chemical reaction
nuclear
Fission and fusion are examples of
nuclear energy reactions
What is NOT a form of natural decay or natural transmutation?
nuclear fission
Conservation of mass number and electrical charge are critical concepts in
nuclear physics, and are essential to understanding how nuclear reactors work, how elements are formed in stars, and how radioactive materials decay overtime.
Age =
number or half lives * half-lives of radioactive isotopes
Natural or spontaneous reactions have
one reactant
Which phrase describes a risk associated with producing energy in a nuclear power plant? depletion of atmospheric hydrogen (H2) depletion of atmospheric carbon dioxide (CO2) production of wastes needing long-term storage production of wastes that cool surrounding water supplies
production of wastes needing long-term storage
Which particle has a mass approximately equal to the mass of a neutron?
proton
Which subatomic particle has has a mass of 1 and a charge of +1?
proton
Symbols in a nuclear equation reveals a lot about the nuclear chemistry particles involve in the
reaction
The total mass before and after the reaction must be
reserved
Gamma rays can also be emitted from natural sources such as
rocks and soil, and from man-made sources such as consumer products that contain radioactive isotopes
Prolong and high dose exposure to radiation can cause
serious health issues, and sometimes death
Radioisotope tracers in medical uses must have
short half-lives, and be able to quickly eliminate from the body
Nuclear Equation
shows changes that are taking place during a nuclear reaction. Include isotope and nuclear particle notations, unlike chemical equations, which include chemical formulas
Cut the larger (original) mass in half as many times as it takes to get to the
smaller (remaining) mass.
During a nuclear reaction,
the mass number of the reactants must equal the mass number of the products.
The mass number of a nucleus is defined as
the total number of protons and neutrons in the nucleus
Nuclear reactions are also called _______________ reactions.
transmutation
Uranium-235 and Uranium-238 are
two naturally occurring isotopes of uranium that play significant roles in various applications
Sunscreen is primarily used to protect the skin from damage caused by
ultraviolet (UV) radiation, which is a different type of radiation than gamma rays.
Alpha decay
when a radioisotope breaks down to release alpha particles