Modern Atomic Theory

1. Modern Atomic Theory • All matter is made of tiny particles called ______Each atom is made up of smaller subatomic particles called ___________________________________________ • The atoms of one element cannot be converted into the atoms of any other element by ____________________ • All the atoms of one element have the ______________, such as average _______________. These properties are different from properties of the atoms of any other element. (what law explains this?) • Atoms of different elements combine in _____________________________(what law explains this?)

2. Lesson #4 - Radioisotopes

3. Review of Isotopes • Same number of ___but have a different number of ____ • Same _________________but a different _______________________ • Many elements (~69) that exist as __________

6. 3 Types of Change • 1. Physical • 2. Chemical • 3. Nuclear Reaction: change that occurs within ________________________________

7. Nuclear Reactions • The number of ________in the nucleus change • This reaction can convert an atom of one element ___________________________ • Nuclear reactions involve _____________________________________ • Eg. The sun, nuclear power station, nuclear reactor, nuclear bomb.

8. Old School Atom DocumentaryNuclear Reactions • http://www.youtube.com/watch?v=_f4kYYAQC3c&feature=related • http://www.youtube.com/watch?v=RMWOfbcAbgo&feature=related

9. Radioactivity Radioactivity is the term used to describe the natural process by which some atoms of _______________ of elements spontaneously disintegrate, emitting particles and energy as they transform into more ____________________. Atoms of some elements are unstable, having ______________________________________________ An unstable nucleus emits particles and energy until it becomes stable. Some chemical elements, including uranium, radium, thorium, and polonium, are ___________________. Any element that is not naturally radioactive can be made radioactive in a nuclear reactor or particle accelerator.

10. Radioactivity Each radioactive element, _________________, has a ____________________, which is the time it takes for one half of the atoms of a particular radioisotope to disintegrate (or decay) into another nuclear form. The longer the half-life of a radioisotope, _____________________________________________

11. Uranium -238 • Uranium can be found in low levels in all rock, soil and water. It occurs in most rocks in concentrations of 2 to 4 parts per million and is also found in the oceans, at an average concentration of 1.3 parts per billion. • http://www.bbc.co.uk/news/world-europe-11074645

12. Isotopes of Uranium 238 • Uranium is a _______________, comparable to lead. • Uranium is as common as tin, tungsten and molybdenum, and about 40 times as common as silver. • Most uranium exists as ______________________ (99.2745 %). The rest is __________________________________

13. Uranium and Nuclear Reactors • The rare uranium isotope U-235 is the fuel most widely used by nuclear plants for fission because its ____________________________________ • One ton of uranium can produce more than 40 million kilowatt hours of electricity, equal to 16,000 tons of coal or 80,000 barrels of oil. • There are a number of areas around the world where the concentration of uranium in the ground is sufficiently high that it can be economically extracted for nuclear fuel. ____________________________________________

14. Uranium 235

15. Uranium 238Nuclear Equation • Rules for balancing nuclear reactions: • 1. The ____ of the ____________ (top) on each side of the ______________________ • 2. The ____ of the _______________ (bottom) on each side of the equation must ___________ • Side note: you have been assigned only equations dealing with alpha particle emission, or alpha decay. You will learn about the effects of beta and gamma rays, but in terms of equations, you only need to know those elements that lose a helium nucleus. (2 protons and 2 neutrons) Helium will always be a part of your products, on the right side of your nuclear equation. This is discussed in more detail on pg. 142-143 (top only) of your textbook.

16. Uranium 238Nuclear Equation • After time, radioactive elements begin to _______ • Uranium decays into atoms of _____________________________ • Note that ______________________ have formed the nuclei of the ___________________and that it’s neutrons have also become part of the new nuclei • This is an example of ______________, where an alpha particle is a helium nucleus, composed of 2 p+ and 2n0

18. Practice Problems • Radon-222 is known to decay by alpha particle emission. Write a balanced nuclear equation and name the element produced in this decay process. • Write the balanced nuclear equation for Plutonium-242 • Write the balanced nuclear equation for Neodymium-144.

19. Radioactivity • When new nuclei are formed, _______________________________ speed away from the reaction into the surrounding environment. • This stabilizing process emits _______________________________________from the nucleus, each of which is energetic enough to break chemical bonds and able to damage or destroy living cells. • This radioactivity is also known as ___________________________

20. Ionizing Radiation • http://www.youtube.com/watch?v=K_zc1WKT0CA • Ionizing Radiation removes _____________ from molecules in living tissues and can seriously disturb their function. Nuclear radiation is a form of ionizing radiation. • Another form frequently used in medicine are x-rays. X-rays do not come from the nuclei of unstable atoms, but are produced by machines that which accelerate electrons to produce a beam of high energy waves.

21. What radiation comes out of X-Rays • http://www.ehow.com/video_5112777_radiation-comes-out-x_rays_.html • Radiation from X-rays is similar ______________________________, so the same precautions must be taken.

22. Penetrating PowerDepending on the type of nuclear reaction, different types of radioactivity are emitted as the nucleus decays.

23. Background Radiation • http://www.youtube.com/watch?v=IXpm5ihBSPM&feature=related • Radon-222 • Cosmic radiation • Potassium-40 in the body • Polonium-210 in tobacco (smokers are exposed to more than 3x the radioactivity than non-smokers)

24. Naturally Occurring Radioisotopes • There are about 30 naturally occurring radioisotopes which are __________________________________, transforming over time into other elements. • Eg. Carbon-14, Chlorine-36, Lead-210 • These isotopes are used in radiometric dating, mostly known as ___________________

25. Carbon Dating?

26. Carbon-14 Dating • http://science.howstuffworks.com/environmental/earth/geology/carbon-14.htm • The ________of carbon-12 to carbon-14 at the moment of death is the same as every other living thing, but the carbon-14 ________________________ • The carbon-14 decays with its half-life of ___________, while the amount of carbon-12 remains constant in the sample. • By looking at the ratio of carbon-12 to carbon-14 in the sample and comparing it to the _______________________it is possible to determine the age of a formerly living thing fairly precisely.

28. Artificially Produced Radioisotopes • Americium-241:Used in backscatter gauges, smoke detectors, fill height detectors and in measuring ash content of coal. • Caesium-137:Used for radiotracer technique for identification of sources of soil erosion and deposition, in density and fill height level switches. • Chromium 57:Used to label sand to study coastal erosion. • Cobalt-60, Lanthanum-140, Scandium-46, Silver-110m, Gold-198:Used together in blast furnaces to determine resident times and to quantify yields to measure the furnace performance. • Cobalt-60: Used for gamma sterilization, industrial radiography, density and fill height switches.

29. AECL Chalk River – Medical Isotopes • http://www.youtube.com/watch?v=aUJueJEZKoo&feature=related

30. Factors to take into consideration when using medical radioisotopes

31. Penetrating Power

32. “The Radium Girls” • The Radium Girls were a group of female factory workers who contracted radiation poisoning from painting watch dials with glow-in-the-dark paint at the United States Radium factory in Orange, New Jersey around 1917. The women, who had been told the paint was harmless, ingested deadly amounts of radium by licking their paintbrushes to sharpen them; some also painted their fingernails with the glowing substance.

33. Rate of Radioactive Decay • __________________ • Some radioisotopes take hours to decay and some take years. • Determines shelf life, transportation, disposal, and how long the _____________________________________________ • Eg. Molybdenum-99 from AECL = 66h, Technetium-99 = 6h.

34. Size of Dose • A large dose of radioactivity in a few hours is way _______________ then that same dosage _______________________________ • People who work with radiation wear special counters to ensure their accumulated exposure is well below the accepted time. • Radiation is measured in RADS – ____________________________ • Matt will talk more about this

35. Type of Tissue • Exposure to body cells can cause _________________ • Exposure to __________ can affect human offspring – called _________________ • Biology review!

36. Reproduction is amazing! Chemistry + Biology +(unfortunately) Physics = circle of __________________

37. Uses of Medical Isotopes • A radioisotope used to diagnose abnormalities such as ________________________ must have a good penetration and be easily detected. What kind of radioisotopes do you think would be best to use? • The radioisotope must be an element needed by the tissue and also _________ in such a way that there is time for the body to take it into the tissue and for a scanner to detect it. • It’s ____________________________________ that it will not stay in the body long enough to cause damage.

38. Technetium-99 • One of the first ____________________ • Discovery: Carlo Perrier, Emilio Segre 1937 (Italy) found it in a sample of molybdenum that had been bombarded with neutrons. • Technetium-99 is used in many medical ____________________

39. Technetium scintigraphy of a neck of Graves' disease patient In the use of technetium-99m, the radioisotope is administered to the patient and the escaping ____________________ are incident upon a moving gamma camera which computes and processes the image. Technetium-99m ____________________________and emits primarily a gamma ray (allowing small amounts to be easily detected), its quick decay into the far-less radioactive technetium-99 results in relatively _________________________________per unit of initial activity after administration, as compared to other radioisotopes.

40. Uses of Medical Radioisotopes • http://www.youtube.com/watch?v=OK7yOyI6GLI&feature=related • Radioisotopes are used both _____________________________ to treat cancer because they destroy rapidly dividing cells. • High energy gamma radiation can come from ___________________________

41. Internal Radiation Therapy • Radioisotope must be ____________ into the tumor • __________________ radioactivity usually used. • Radiation accumulates in the tumor and destroys the tumor and not the surrounding tissue. • ______________________________________ are surgically implanted into tumors • ____________________ is used to battle leukemia • _________________ is used for thyroid problems

42. Sterilization of Medical EquipmentCobalt-60 • As a tracer for cobalt in chemical reactions, • _______________________________________________ • Radiation source for medical radiotherapy, • Radiation source for industrial radiography, • Radioactive source for leveling devices and thickness gauges, • As a radioactive source for food irradiation and blood irradiation, and • ______________________________________________

43. Lots of new stuff………….. • Any questions? • Take some time now and try the questions in the Self-Check #1 section • Make note of any specific questions to ask our guest speaker, Matt. • Homework: all the questions for lesson #4. There are quite a few so it makes me think that this stuff is important! • Readings for Lessons #5 & #7 (6 is the lab)