The Process of Nuclear Fusion and Nuclear Fission

Nuclear fission -

-->The process in which a large nucleus splits into two smaller nuclei with the release of energy. An electron is added to a nucleus and because it overcomes the strong force the nucleus splits into two smaller nuclei.

Pu239 & U235 are the most common isotopes for nuclear fuel. They perform nuclear fission very easily.

-->It provides energy for nuclear power plants, using chain reactions, (on right). A chain reaction is when a series of nulcear fissions happen. When one Nucleus splits into two others it also breaks off a few neutrons. Then those neutrons hit other big nucleus' and it's a chain reaction. Hence the name.

--> The nuclear power plants: Uranium-235 undergo a nuclear chain reaction, controlled by rods. The energy heats the water, and produces steam. The steam then turnes a turbine that is attached to a generator, the generator converts the energy into electricity.

n + 235U -> 141Ba + 92Kr + 3n

Nulcear fusion -

-->Two or more nuclei with small masses join together to form a larger, more massive nucleus.

ex. 4 hydrogen-1 (with a charge of 1+) come together to form Helium-4 (with a charge of 2+). For this to happen temperatures have to reach 100,000,000 degress Celcius. Energy is given off as well as a few beta particles.

--> Temperatures are too hot to be able to try and develope, and maintain, on earth. A good example of where nuclear fusion happens is in the core of our sun.

-->The fussion of nuclei lighter than iron or nickle ussually gives off energy. While fussion of nuclei heavier than iron or nickle ussually absorb energy. (iron and nickle are most stable)

p + p -> 2 H + e+ + n + .42 MeV

Holt, Rinhart, and Winston. Interactions of matter. 2002 (book)

Wikipedia, Nuclear chain reaction. (http://en.wikipedia.org/wiki/Nuclear_chain_reaction)

Kenneth R. Koehler. Nulcear Reactions. 1996 (http://www.rwc.uc.edu/koehler/biophys/7b.html)

A Distinction Between Nuclear Reactions and Chemical Reactions

The definition of a nuclear reaction from www.dictionary.com is a reaction, as in fission, fusion, or radioactive decay, that alters the energy, composition, or structure of an atomic nucleus.

The definition of a chemical reaction from www.dictionary.com is a process in which atoms of the same or different elements rearrange themselves to form a new substance. While they do so, they either absorb heat or give it off. When they absorb heat it is called an endothermic reaction and when they give off heat it is called an exothermic reaction.

The are six main differences between these nuclear reactions and chemical reactions.
In nuclear reactions...

1. protons and neutrons react inside the nucleus
2. elements transmute into other elements
3. isotopes react differently
4. independent of chemical combonation
5. energy changes equal 10^8 kJ
6. mass changes are detectable

In chemical reactions...

1. electrons react outside the nucleus
2. the same number of each kind of atom appear in the reactants and products
3. isotopes react the same
4. depend on chemical combination
5. energy changes equal 10^3 kJ/mol
6. mass reactants=mass products

NuclearReactions versus Chemical Reactions. http://www.cartage.org.lb/en/themes/sciences/chemistry/NuclearChemistry/NuclearReactions/versusChemicalReactions/ChemicalReactions.htm

A Comparison of the Amount of Energy Released Through a Chemical Reaction and Nuclear Fusion nd Fission

To begin, neuclear reactions release more enegry than chemical reactions.
Neuclear energy consists of fusion and fission. Neuclear fission is the process in which a large nucleus splits into two smaller nuclei with the release of energy as mentioned in our first post, while neuclear fusion is when two or more nuclei with small masses join together to form a larger, more massive nucleus. As you can immagine this takes a whole lot of energy. Massive amounts are released/created when a nucleus splits or when nuclei join. The reason fission takes so much energy is because both nuclei have positive charges which as you may know repel (like charges repel and opposites attract). Neuclear fission also takes and relases massive amounts of energy because of the proccess. For it to occur an atom must be unstable and unbalaced so it will want to split. If a neutron is shot to a nucleus very, very fast then protons out number neutrons creating an unbalanced and unstable atom. For the atom and nucleus to become more stable the nucleus must split making two nuclei so protons and neutrons are equal again. The law of concervation of energy states tha energy cannot be created or destroyed. This just shows how big fission and fusion are since as you now know fission destroys and fusion creates.

Compared to fission and fusion chemical reactions seem like nothing. Chemical reactions are just changes in energy. In exothermic reactions energy is released but not destroyed and in endothermic energy is absorbed but not created. It's just a transfer of energy. Some cluses to chemical reactions include gas formatioin, solid formation, color change, and energy change. An example of a chemical reaction is rusty nails the element of iron in the steal reacts with the oxygen in the air creation rust. This is a chemical reaction.

In conclusion neuclear reactions have a much greater amount of energy released than chemical reactions.

Utah Educatioin Network
Chemical reactions- http://www.usoe.k12.ut.us/curr/science/sciber00/8th/matter/sciber/chemtype.htm

Lawrence Berkeley National Laboratory:
Neuclear Fission- http://www.lbl.gov/abc/wallchart/chapters/14/1.html
Neuclear Fusion- http://www.lbl.gov/abc/wallchart/chapters/14/2.html

Properties of Elements and Their Radioactive Isotopes

Isotopes containing 83 protons or more are radioactive, although same may take billions of years before they decay, they will decay. These isotopes are called unstable.

By http://www.dictionary.com/ the chemistry definition of unstable is, "noting compounds that readily decompose or change into other compounds." This means that an unstable atom will eventually decompose and give off radioactive decay.

What makes an isotope radioactive?
-->Well first, as described earlier isotopes cantain 83 or more protons are radioactive. This is because the strong force (an attractive force that holds the protons and neutrons together in a nucleus) only works at very short distances. A nucleus with 83 or more protons is too big for the strong force to keep the protons together, so sooner or later the nucleus will decompose.
ex. Polonium has an atomic number of 84. All the isotopes of polonium are radioactive/

-->Another way for a nucleus to be unstable is if it contains too many or too few neutrons. It all depends on ratios. When nuclei have more than 60 protons they need a ratio of neutrons to protons of 3 to 2 to be stable. When nuclei have less than 20 protons they need a ratio of 1 to 1 to be stable.
ex. Hydrogen-3 has a ratio of 2 neutrons to 1 proton. Because there are less than 20 protons it needs a ratio of 1 to 1 to be stable. The ratio is greater so this means Hydrogen-3 is unstable and therefore radioactive.
ex. Beryllium-10 has a ratio of 3 to 2. It has 6 neutrons and 4 protons. This isotope is radioactive because its ratio is greater than 1 to 1.


Holt , Rinehart, and Winston. Interactions of Matter. 2002 (book)

How Isotopes Can be Used

Medicine- Scans can be made to show tumors using radioactive iodine-131. The nuclei has a very short half life so the exposure is low. Tracers are used to help docotors diagnose problems, such as cancer.
-->Tracer- A radioactive element whose path can be followed through process or reaction. (ex. iodine-131)
-->Radioactive elements can also be used to treat cancer, not just find it.
-->Gamma Rays can be used to sterilize medical equipment. Gamma Rays- a form off light given off from a radioactive nuclei with a very high energy.

Industry- Radioactive isotopes can detect defects in structures, find weak spots in metal, and leaks in pipes. (Using a geiger counter) Again tracers are used in the process.
ex. Radiation is used to test the thickness of metal sheets as they are being made.

Electricity Generation-
**Nuclear Power Plants** click here to see a diagram

Uranium-235 undergoes a nuclear chain reaction. Then the energy is absorbed in a coolant, which is usually water, and then the water turns to steam. The steam turns a turbine and spins the generator. The generator then converts the energy into electricity.

Research-

Isotopes of radiation atoms are always being used in research.

new ways to treat diseases

new ways to help building structures

new ways to use nuclear energy without waste

and they're always trying to find new things about the isotopes themselves.

Hailf life- The amount of time it takes for 1/2 of the radioactive nuclei to decay.

Origional- Contaons all of the radioactive isotope.

Half Life- Half was decayed, half is unchanged.

2 Half Lives- 1/4 is unchanged.

3 Half Lives- 1/8 is unchanged.

Ex. Isotope.......................... Half Life

Uranium-238.....................4.5 billion years

Oxygen-21......................... 3.14 seconds

Hydrogen-3....................... 12.3 years

Holt, Rinehart, and Winston. Interactions of Matter. (book)

CASEnergy Coalition. Clean and safe energy. (http://www.cleansafeenergy.org/Portals/0/student-pwr.gif)

Nuclear Power of the Future. John Giacobello. 2003

Types of Radiations Produced from Nuclear Reactions

Alpha

Alpha radiation is a positively charged particle made up of two neutrons and two protons. It is the least penetration of alpha, beta, and gama radiation. It can be stopped by a sheet of paper. Alpha particles consist of two protons and two neutrons (as stated before) bound together into a particle identical to a helium neucleus. The alpha particle mass is 6.644656×10-27 kg. It is about 8000 times heavier than an electron and has a double electric charge. The charge of an alpha particle is equal to +2e, where e is the magnitude of charge on an electron, e=1.602176462x10-19C. Alpha Radiation is emitted when heavy, unstable nuclides, for example uranium, radium, radon and plutonium, undergo decay. Beta and gama radiation are more penetratalbe than alpha. If alpha radiation hits the outside of an unshielded human, it cannot penetrate through the skin's outer layer of dead corneous cells so it does no damage. Alpha-emitting materials can be harmful to humans if the materials are inhaled, swallowed, or absorbed through open wounds. Alpha radiation cannot penetrate through clothing. The reason alpha decay occurs is because the nucleus has too many protons which cause excessive repulsion. Since an atom loses two protons during alpha decay, it changes from one element to another because as we learned near the begining of the year atoms are named for their amount of protons. For example, after undergoing alpha decay, an atom of Americium (with 95 protons) becomes an atom of Neptunium (with 93 protons). Another way to explain alpha decay is the release of an alpha particle from a nucleus. Here is an example of alpha decay:


http://www.lbl.gov/abc/wallchart/chapters/03/1.html

alpha particle radiation picture- http://www.fbr.org/swksweb/alphaamer.gif

Beta Radiation

Beta radiation is emitted during the radioactive decay of many beta-active, unstable nuclides. Beta radiation is is a type of radioactive decay in which a beta particle (an electron or a positron) is emitted. The beta particle (an electron), is emitted when a neutron in a nucleus is transformed into a proton. The beta particle is very light and its mass is about 1/2000 that of the proton. Beta particles are high-energy, high-speed electrons or positrons emitted by certain types of radioactive nuclei such as potassium-40. The beta particles emitted are a form of ionizing radiation also known as beta rays. Beta radiation may travel meters in air and is moderately penetrating. Some examples of pure beta emitters: strontium-90, carbon-14, tritium, and sulfur-35. If high levels of beta-emitting contaminants are allowed to stay on the skin for a prolonged period of time, they can cause skin injury, but clothing provides some protection agains beta radiation. As mentioned before beta particles are able to penetrate living matter, but only to a certain extent. They are more penetrateable that alpha particles but less penetratable than gama particles. Beta decay is a type of radioactive decay in which a beta particle (an electron or a positron) is emitted. There are two versions of beta deca. The first one is called beta minus decay which is when a neutron decays into a proton, an electron, and antineutrino. In beta plus decay a proton decays into a neutron, a positron, and a neutrino. Beta plus and minus decay happen because of the same reason. It is because in different parts of the chart of the Nuclides one or the other will move the product closer to the region of stability.

http://www.lbl.gov/abc/wallchart/chapters/03/2.html
beta partical radiation picture- Princeton University http://web.princeton.edu/sites/ehs/ssradtraining/beta.gif

Gamma Radiation

Gamma radiation is more reactive than both alpha and beta radiation. "Alpha radiation is a heavy, very short-range particle and is actually an ejected helium nucleus....Beta radiation is a light, short-range particle and is actually an ejected electron....Gamma radiation and x rays are highly penetrating electromagnetic radiation." This information can be found here. That is why I will not be speaking of gama particles. The release of gamma rays doesn't change the number of protons or neutrons in the nucleus, but in its place has the effect of moving the nucleus from a higher to a lower energy state or in less words unstable to stable. Gamma radiation and x rays are electromagnetic radiation. This includes rays like visible light, ultraviolet light, and radiowaves. They eagerly penetrate most materials which is where they came up with the nick name "penetrating" radiation due to the fact that they are the most reactive of the three most common types of radiation. Clothing will revent contagion of the skin from materials that are gamma radioactive, but it provides little shielding from penetrating radiation. Gamma decay is the procedure when the atom's nucleus gives off a high energy photon (an extremely short-wavelength electromagnetic radiation). I've all ready explained alpha and beta decay so this should make more sense now, but to learn more about gamma decay go to this website.

http://www.lbl.gov/abc/wallchart/chapters/03/3.html

Gamma-ray radiation picture- Princeton University http://web.princeton.edu/sites/ehs/ssradtraining/gamma.gif

(this picture)- Idaho Department of Enviromental Quality http://www.deq.idaho.gov/inl_oversight/radiation/images/alpha_beta.jpg

Alpha, Beta, Gamma Radiation- by George W. Dowell http://www.blackcatsystems.com/GM/articles/alpha_beta_gamma_radiation.html

Alpha, Beta, Gamma Decay- NDT Resource Center http://www.ndt-ed.org/EducationResources/CommunityCollege/Radiography/Physics/gamma.htm

This site also contains an animation of radioactive decay.

Alpha and Beta Particles- Jefferson Lab http://education.jlab.org/glossary/index.html

Other information- Health Physics Society http://hps.org/publicinformation/ate/q386.html

How Nuclear Energy can be Understood Using Patterns

There are a few patterns that are evident in nuclear energy. These are radioactive half-life and nuclear chain reaction.

Radioactive Half Life is a pattern of decay in a radioisotope. After two half-lives there is 1/4 of the amount of mass left and after three half-lives there is 1/8 the amount of mass/material left. This goes on and on. Every time a half-life occurs the amount of material/mass is half of what it was before.

Nuclear Chain Reaction is a continuous series of nuclear fission reactions. It is kind of like dominoes. When one falls over it reacts all of the other dominoes and they all topple over.

Click here to check out a cool video of a nuclear chain reaction.

Click here to check out a cool interactive activity involving nuclear chain reaction.




My sources were........
Radioactive Half Life. Feb. 28, 2008. http://hyperphysics.phy-astr.gsu.edu/hbase/nuclear/halfli2.html

Holt, Rinehart and Winston. Interactions of Matter. Austin: A Harcourt Classroom Education Company, 2002.