1. Nuclear Chemistry
Chapter 10

2. Complete the table to indicate how many protons and neutrons are in the nuclei of the following atoms:

3. Nuclear Radiation
radioactivity - process by which an unstable nucleus emits one or more particles or energy in the form of electromagnetic radiation
nuclear radiation - particles that are released from the nucleus during radioactive decay
There are different types of nuclear radiation.

4. Types of Nuclear Radiation

5. Nuclear energy – energy that exists within the nucleus of an atom
Nuclear fission – process of breaking apart subatomic bonds which releases large amounts of energy
Disadvantage of nuclear energy:
Produces radioactive waste
In short supply ( years at current consumption rate)
Extremely expensive
Safety concerns:
Extremely dangerous if explodes – which will contaminate thousands of miles of land
Nuclear fission has both advantages and disadvantages.
Nuclear fission is an alternative to fossil fuels as a source of energy.
Radioactive products of fission must be handled carefully and nuclear waste must be safely stored.
Nuclear fusion reactors are being tested.
Nuclear fusion reactions are difficult to produce in the laboratory.
Nuclear fusion also has advantages and disadvantages.

6. An example of nuclear fission is the explosion of an atomic bomb
The first atomic bomb was dropped by the U.S on Hiroshima, Japan during WWII
Nuclear materials are an extraordinarily rich energy source
One gram of uranium-235, the most common nuclear fuel, delivers about as much energy as 3.5 metric tons of coal
Nuclear energy does not produce carbon dioxide

7. Nuclear Explosion at Chernobyl
                               

8. The nuclear reactor at Chernobyl was covered up with concrete and steel to stop any more radiation from escaping
16 years later the soil is still being tested

9. In the United States a massive effort to build an atomic bomb was launched in 1942.
The code name was the Manhattan Project. This
project was carried out in extreme secrecy On July 16, 1945, in the desert near Alamogordo, New Mexico, the US successfully conducted the world's first nuclear test.

11. It is a safer energy source than nuclear fission Difficult to achieve
Nuclear fusion – lightweight atomic nuclei combining to form a heavier nucleus, basically the opposite of nuclear fission
Process which powers the stars, which includes our sun – temperature up to 10,000,000oC
It is a safer energy source than nuclear fission
Difficult to achieve

12. Transuranium elements – having an atomic # greater than 92
Quark – subatomic particle theorized to be among the basic units of matter
Transuranium elements – having an atomic # greater than 92
Plasma – state of matter in which atoms have been stripped of their electrons
Exists at high temperatures
All transuranium elements are readioactive

13. Alpha particles consist of protons and neutrons.
An alpha particle is a positively charged atom that is released in the disintegration of radioactive elements and that consists of two protons and two neutrons.
Beta particles are electrons produced from neutron decay.
A beta particle is a charged electron emitted during certain types of radioactive decay, such as beta decay.

14. Gamma rays are very high energy.
A gamma ray is a high-energy photon emitted by a nucleus during fission and radioactive decay.
Neutron radioactivity may occur in an unstable nucleus.
Neutron emission consists of matter that is emitted from an unstable nucleus.
Neutrons are able to travel farther through matter than either alpha or beta particles.

15. A nucleus gives up two protons and two neutrons during alpha decay.
In nuclear decay, the sums of the mass numbers and the atomic numbers of the decay products equal the mass number and atomic number of the decaying nucleus.
A nucleus gives up two protons and two neutrons during alpha decay.
The process of the alpha decay of radium-226 is written as follows.

16. A nucleus gains a proton and loses a neutron during beta decay.
A beta decay process occurs when carbon-14 decays to nitrogen-14 by emitting a beta particle.

17. Nuclear Decay Actinium-217 decays by releasing an alpha particle
Nuclear Decay Actinium-217 decays by releasing an alpha particle. Write the equation for this decay process, and determine what element is formed.
1. Write down the equation with the original element on the left side and the products on the right side.
Use the letter X to denote the unknown product. Note that the mass and atomic numbers of the unknown isotope are represented by the letters A and Z.

18. 2. Write math equations for the atomic and mass numbers.
217 = A – = Z – 2
3. Rearrange the equations.
A = 217 – 4 Z = 89 – 2
4. Solve for the unknown values, and rewrite the equation with all nuclei represented.
A = Z = 87
The unknown decay product has an atomic number of 87, which is francium, according to the periodic table. The element is therefore

19. The half-life is the time required for half of a sample of a radioactive substance to disintegrate by radioactive decay or by natural processes.
Half-life is a measure of how quickly a substance decays.
Using half-lives, scientist can predict how old an object is.
Carbon-14 is used to date materials.

20. Half life

21. 1. List the given and unknown values.
Half-life Radium-226 has a half-life of 1599 years. How long would it take seven-eighths of a radium-226 sample to decay?
1. List the given and unknown values.
Given: half-life = 1599 years
fraction of sample decayed = 7/8
Unknown: fraction of sample remaining = ?
total time of decay = ?

22. 3. Calculate the number of half-lives.
2. Calculate the fraction of radioactive sample remaining.
To find the fraction of sample remaining, subtract the fraction that has decayed from 1.
3. Calculate the number of half-lives.

23. 4. Calculate the total time required for the radio-active decay.
3. Calculate the number of half-lives
Three half-lives are needed for one-eighth of the sample to remain undecayed.
4. Calculate the total time required for the radio-active decay.
Each half-life lasts 1599 years.

24. Nuclei are held together by a special force.
Protons and neutrons are tightly packed in the tiny nucleus of an atom.
strong nuclear force causes protons and neutrons in the nucleus to attract each other. This attraction is much stronger than the electric repulsion between protons.
Neutrons contribute to nuclear stability.
Too many neutrons or protons can cause a nucleus to become unstable and decay.

25. Forces in the Nucleus

26. Fission is the process by which a nucleus splits into two or more fragments and releases neutrons and energy.
One type of fission of uranium-235 can be repre-sented by the following equation.
The equivalence of mass and energy observed in nature is explained by the special theory of relativity
Energy is released during a nuclear fission.
The equivalence of mass and energy observed in nature is explained by the special theory of relativity.
This equivalence is expressed by the following equation.
E = mc2
mass x (speed of light)2
Mass-Energy Equation

27. Neutrons released by fission can start a chain reaction.
nuclear chain reaction is a continuous series of nuclear fission reactions.
Chain reactions can be controlled.
If there is less than a critical mass of a fissionable isotope, a chain reaction will not occur.

28. critical mass is the minimum mass of a fissionable isotope that provides the number of neutrons needed to sustain a chain reaction.
Nuclear fusion is the process in which light nuclei combine at extremely high temperature, forming heavier nuclei and releasing energy.
Nuclear fusion occurs in the sun.
Four hydrogen atoms fuse together in a multi-step process to produce a helium atoms and enormous energy in the form of gamma rays.

29. Background radiation - the nuclear radiation that arises naturally from cosmic rays and from radioactive isotopes in the soil and air.
rem - the quantity of ionizing radiation that does as much damage to human tissue as 1 roentgen of high-voltage X rays does.
Radiation is measured in units of rems.

30. Exposure varies from one location to another.
Some activities add to the amount of nuclear radiation exposure.
Some activities add to the amount of nuclear radiation exposure.
Smoke detectors help to save lives.
In a smoke alarm, a small alpha-emitting isotope detects smoke particles in the air.

31. Nuclear radiation is used to detect diseases.
A radioactive tracer is a radioactive material that is added to a substance so that its distribution can be detected later.
Radioactive tracers are widely used in medicine.
Nuclear radiation therapy is used to treat cancer.
Radiotherapy is treatment that uses controlled doses of nuclear radiation for treating diseases such as cancer.
Agriculture uses radioactive tracers and radio-isotopes.
On research farms, radioactive tracers help scientists to understand biochemical processes in plants.

32. MRI Image of brain Normal brain Alzheimer’s brain
Nuclear radiation can ionize atoms.
Ionization is a change in the number of electrons in an atom or molecule, causing the particle to be positively or negatively charged.
Radiation sickness results from high levels of nuclear radiation.
People working in radioactive areas wear a dosimeter, a device that measures the amount of nuclear radiation exposure.
Studies have shown a relationship between exposure to high levels of nuclear radiation and cancer.
The risk depends upon the amount of radiation exposure.
High concentrations of radon gas can be hazardous.
Radon gas is colorless and odorless, and is produced by the decay of uranium-238 present naturally in soil and rock.
Tests for radon gas are widely available
Normal brain
Alzheimer’s brain

33. THE END
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