JOURNAL # 1 Share your thoughts on radioactivity. What is good about it? What is bad about it? Is it something that should be used or experimented with by humans… or avoided? Totally? Partially? In some ways but not others?

Radioactivity Notes Tim F. Rowbotham 2010

Nuclear Stability In the nucleus, protons and neutrons are held together by the strong nuclear force. It overcomes the weaker electric force of repulsion.

Nuclear Instability But some atoms have unstable nuclei. The strong force is not great enough. Their nuclei have a tendency to “fall apart” a bit due to this instability.

Nuclear Radiation Unstable nuclei will jettison some particles or energy in order to become more stable.

Nuclear Radiation The particles or energy ejected from the nucleus of an atom is what we call nuclear radiation.

They are called radioactive isotopes, or radioisotopes for short. Radioactive Elements Radioactive elements are those atoms that have unstable nuclei, thus would eject particles or energy from their nuclei. They are called radioactive isotopes, or radioisotopes for short.

Radioactive Decay When an atom gives off nuclear radiation, we call the process radioactivity or nuclear decay. During nuclear decay, an atom may change into an entirely new element. (Remember, the number of protons is what determines the type of atom.)

Nuclear Decay Products Through nuclear decay, an element can change to another element, so we refer to the initial radioisotope as the parent and the element it becomes as the daughter product. PARENT  Radiation + DAUGHTER

Parent & Daughter Elements

Sample Parent & Daughters PARENT  Radiation + DAUGHTER Ra-226  α + Rn-222 U-238  α + Th-234 Th-234  β + Pa-234 C-14  β + N-14 K-42  β + Ar-42

Types of Nuclear Radiation There are 3 common types of nuclear radiation: ALPHA PARTICLES BETA PARTICLES GAMMA RAYS

Alpha Decay In alpha decay, an alpha particle is released from the nucleus. An alpha particle is 2 protons attached to 2 neutrons. It is the same as a helium nucleus.

Alpha Decay education.jlab.org/glossary/alphadecay.htm

Alpha Decay http://santasusana.org/pakelly/G%20Chemistry/changes_in_the_nucleus.htm

Alpha Decay http://www.umich.edu/~radinfo/introduction/lesson/alpha.htm

Alpha Decay http://www.hk-phy.org/resources/images/atomic01/?N=A

Beta Decay In beta decay, a beta particle is released from the nucleus. A beta particle is really an electron. During beta decay, a neutron changes into a proton and electron. The proton stays and the electron is jettisoned from the nucleus.

Beta Decay education.jlab.org/glossary/betadecay.htm

Beta Decay http://santasusana.org/pakelly/G%20Chemistry/changes_in_the_nucleus.htm

Beta Decay www.physics.isu.edu/adinfbeta.htm

Beta Decay http://www.hk-phy.org/resources/images/atomic01/?N=A

Gamma Decay In gamma decay, no particle is released by the nucleus – only energy!! Gamma decay, by itself, does not change the atom into a new element. Gamma decay often accompanies alpha or beta decay.

Gamma Decay http://santasusana.org/pakelly/G%20Chemistry/Gammae.gif

Gamma Decay http://www.umanitoba.ca/faculties/medicine/radiology/stafflist/staffitems/RADPRO%20Course/radiation.htm

Gamma Decay http://www.newworldencyclopedia.org/entry/Gamma_ray http://www.odec.ca/projects/2007/pete7o2/Background.html

Nuclear Decay Equations

Radiation Penetration The types of nuclear radiation have differing abilities to penetrate matter. How to block Paper Thin sheet of metal 3 ft of concrete 3 in of lead TYPE ALPHA PARTICLE BETA PARTICLE GAMMA RAY or

Radiation Penetration

Radiation Penetration

Radiation Penetration Video Clip: Alpha Beta Gamma Demonstrated

Effects of Radiation Radiation that occurs naturally every day is called background radiation. Nuclear radiation can ionize atoms – breaking apart the chemical bonds that hold molecules together.

Effects of Radiation

Chernobyl Radiation Effects Effects of Radiation Video Clip: Chernobyl Radiation Effects

One device that detects ionizing radiation is called a Geiger counter. Detecting Radiation One device that detects ionizing radiation is called a Geiger counter.

Rate of Nuclear Decay It is not possible to predict exactly when a particular radioactive atom will emit radiation. However, it is possible to know how many will decay over a certain amount of time.

Half-Life A half-life is the amount of time it takes for half of sample of the parent to decay. (If you start with 100 atoms, it’s the time it takes for 50 to decay.) This time differs depending on the radioisotope.

The number of atoms is cut in half once for every half-life.

Half-Life ionactive.co.uk

Half-Life Every half-life, one half of the parent isotope remaining becomes the daughter element.

Half-Life

Half-Life If we start with 24 radioactive atoms... How many are left after 1 half-life? after 2 half-lives? www.datamentor.org

Half-Life of 3 Hours 500 atoms after 1 half-life. 250 atoms after 2 half-lives. 125 atoms after 3 half-lives. http://ohioline.osu.edu/rer-fact/rer_20.html

Half-Life of 3 Hours 6 hours = 2 half-lives. 9 hours = 3 half-lives. http://ohioline.osu.edu/rer-fact/rer_20.html

RADIOISOTOPE Potassium-37 Hydrogen-3 Carbon-14 Radium-226 Uranium-238 Sample Half-Lives RADIOISOTOPE Potassium-37 Hydrogen-3 Carbon-14 Radium-226 Uranium-238 HALF-LIFE 1.23 seconds 12.26 years 5730 years 1600 years 4,500,000,000 yrs

Radioactive Decay & Half-lives Use the tables in the back of your Radioactivity packet to help you answer these questions 1a.) How much Ra-226 would be left after decay of 5 half-lives of 800g? 1b.) How much time would that take? (HL = 1600 y) 2a.) How much strontium-90 would be left after 4 half-lives of decay of 2000g? 2b.) How long would this take? (HL = 28.1y)

Radioactive Decay & Half-lives Mar 21, 2011 Use the tables in the back of your Radioactivity packet to help you answer these questions 3a.) How much Co-60 would be left after decay of 3 half-lives of 1000 atoms? 3b.) How much time would that take? 3c.) How much daughter would be left? 4a.) How much Iodine-131 would be left after 4 half-lives of decay of 4000 atoms? 4b.) How long would this take? 4c.) I-131 decays by beta decay into what element?

Radioactive Dating Since half-life is a fairly constant rate for each specific element, it is most often used for radioactive dating. The most well-known type is radiocarbon dating which is often referred to as carbon dating.

It can only happen through a change in the nucleus. Transmutation Transmutation is when one type of atom becomes a different type of atom. It can only happen through a change in the nucleus. It is a nuclear change.

Artificial Transmutation Scientists perform artificial transmutations by bombarding nuclei with protons, or neutrons, or alpha particles. Transuranium elements are created by artificial transmutation of smaller elements.

The strong force is greater than the electric force. Strong nuclear force Protons and neutrons are held in the nucleus by the strong nuclear force. The strong force is greater than the electric force. However, the electric force of repulsion increases much more with the addition of subatomic particles.

Strong nuclear force When the electric force of repulsion is greater than the strong force, the atom emits radiation. lbl.gov

Fission is the splitting of an atomic nucleus into two smaller atoms.

Fission al-zen.com

A lot of energy is produced when this occurs. Fission A lot of energy is produced when this occurs. How much? E= mc2 http://library.thinkquest.org/C003730/index.php3?ID=18

Law of Conservation of Mass In chemical reactions, matter can not be created or destroyed, but can change form. In nuclear reactions, however, matter can be converted to energy.

Law of Conservation of Mass and Energy This law is modified when dealing with nuclear reactions. According to the law of conservation of mass and energy, the total amount of mass and energy remains constant.

How are mass and energy related? Mass-Energy Equation How are mass and energy related? E= mc2 c = the speed of light c = 299,792,458 meters per second

Fission Chain Reaction A lot of energy is produced from a fission reaction, however, just one atom has a tiny amount of mass so releases little energy. A chain reaction must be produced. This happens when neutrons released during fission, hit and split other atoms.

Uses of Fission Nuclear Weapons http://www.adapage.com/magazzino/Photo%20Bombe%20Atomiche.htm

Uses of Fission Nuclear Power

Fusion is combining two atoms to form a larger nucleus. alternativeenergyrevealed.com http://mosaic.cnfolio.com/B101CW2007A166

Uses of Fusion Fusion requires extremely high temperatures. It occurs naturally in the sun. neoteo.com

Uses of Fusion We can also produce fusion in a thermonuclear weapon, which is even more powerful. http://www.flickr.com/photos/7969902@N07/510672745/

Share your thoughts on nuclear power. JOURNAL # 2 Share your thoughts on nuclear power. Do you think that the U.S. should be building more nuclear power plants? Support your opinion with logical reasons.

JOURNAL # 3 Explain the difference between alpha, beta & gamma decay as well as nuclear fission & fusion.

Duck & Cover Effects of Nuclear Radiation Effects of Radiation Duck & Cover Effects of Nuclear Radiation http://www.adapage.com/magazzino/Photo%20Bombe%20Atomiche.htm