Radiation

Radiation (Nuclear Decay) First used by Marie Curie (1899-1903) Radiation: Energy released in the form of particle or electromagnetic waves. Measured units: rems/millirems

History 1903 Radiation 1942 First Chain Reaction 1895 X-rays 1 1945 Nuclear Bomb Wilhem Conrad Roentgen Robert Oppenheimer 1903 Radiation 1942 First Chain Reaction In the 1800s, the discovery of photography ultimately lead to the splitting of the atom. The basis of photography is that visible light causes certain chemical reactions – if the chemicals are spread thinly on a surface but protected from light by a covering, no reaction occurs. When the covering is removed, light acting on the chemicals causes them to darken. Roentgen (rentgen) discovered that radiation other than visible light could expose photographic film – film wrapped in dark paper would react when x-rays went through the paper and struck the film. Becqueurel discovered that uranium containing rocks could develop photographic plates – the radiation from the uranium had no connection with light or flouresence, directly proportional to the concentration of uranium Maria Curie was one of Becqurel’s assistants – her and her husband decided to find out if other chemicals were radioactive – studied pitchblend (residue of uranium mining) from mining region in Austria – separated a previously known element radium – found it was many more times radioactive than uranium. - They received the 1903 Novel Prize in Physics - Marie Curie later won the 1911 Nobel Prize in Chemistry for her continued work with radioactivity * She was the first female Nobel laureate and only person to ever receive 2 Nobel Prizes in 2 different scientific categories Marie Curie Enrico Fermi

Radiation is all around Us!! Natural Background Radiation: Cosmic Radiation – the earth, and all living things on it, are constantly bombarded with radiation from space (e.g. sun and stars) Terrestrial Radiation – soil, water, and vegetation Some are ingested with food and water Some are inhaled (e.g. radon) Internal Radiation (K-40, C-14, Pb-210) Found in bodies from birth ** Radiation increases as altitudes increase

Man-made Radiation Medical uses (X-rays, CAT and PET scans) – most significant source Consumer products – tobacco, building materials, combustible fuels (gas, coal, etc.), tvs, luminous watches, Smoke detectors (americium) Lantern mantles (thorium) Chernobyl (First year) and Japan fallout Fallout from weapons testing Job (Average) – radiography, x-ray techs, etc. Nuclear Industry (Waste)

Electromagnetic Spectrum Non-ionizing vs Ionizing Radiation

Particles more energy. They have a greater impact in the body Smaller particles store more energy. They have a greater impact in the body

Dose Response on Tissues April 26, 2017 Dose Response on Tissues Examples of tissue Sensitivity Very High White blood cells (bone marrow) Intestinal epithelium Reproductive cells High Optic lens epithelium Esophageal epithelium Mucous membranes Medium Brain – Glial cells Lung, kidney, liver, thyroid, pancreatic epithelium Low Mature red blood cells Muscle cells Mature bone and cartilage A Small Dose of Toxicology - Overview

Effects of Radiation

Even though we have learned about some harmful effects of radiation, have in mind the following …….. Americans get about 25 mrems of radiation from food and water we eat each year. This number varies depending what is eaten, where it is grown and how much is eaten. E.g. Bananas and Brazil nuts contain higher proportions than most food. Additional amounts of radiation come from man made sources E.g. Mainly medical, dental, construction, and nuclear industry sources Americans average between 150-200 mrems of radiation from all sources each year. Places in India and Brazil may have 3,000 mrems yearly. Radiation levels of 50,000 mrems have not produced any evident ill effects Strict safety standards on radiation exposure allow people to work in science, medicine, construction and nuclear power plants.

Activity # 2 **Answer Review Exercise – p.1 **Total Annual Millirems (mrems) Dose Worksheet. Keep in mind the following facts: 1. Question #2: Monterrey’s Elevation is 537m /1,762 ft 2. Question #7: Research miles traveled per year. Example: Mty-Cancun (Round Trip) = 1900miles 3. Research has shown that 50,000 mrems have not produced any evident ill effects

Nuclear Stability Nucleus contain Protons and Neutrons. Contains a strong Electromagnetic force to hold the Protons together. Nucleus of some elements become unstable releasing energy as the form of radiation.

Radiation can be detected if it: Alters a photographic film Produces an electric charge in the surrounding air Can produce fluorescence (glowing)

Isotopes Atoms of an element with the same number of protons and a different number of neutrons. Therefore their mass number is also different.

Other Isotopes

Analyzing Isotopes Complete the following table : Write the nuclear symbol for atoms with the following subatomic particles: 8p, 8n, 8e = 17p, 20n, 17e = 47p, 60n, 47e =

Analyzing Isotopes Solutions Complete the following table : Protons 14 14 14 Neutrons 14 15 16 Electrons 14 14 14 Atomic # 14 14 14 Mass # 28 29 30 Write the nuclear symbol for atoms with the following subatomic particles: 16 37 A. 8p, 8n, 8e = O B. 17p,20n, 47e = Cl 8 17 47p, 60n, 47e = 107 Ag 47

Copper has two isotopes: Cu-63 and Cu-65 Copper has two isotopes: Cu-63 and Cu-65. Given that the atomic mass of copper from the periodic table is 63.546 amu, which of the two isotopes is most abundant? Explain your answer. Analyze the following chart and determine what elements are isotopes of the same element. Atom A Atom B Atom C Atom D #P 15 10 #N #E Mass

Solutions Copper has two isotopes: Cu-63 and Cu-65. Given that the atomic mass of copper from the periodic table is 63.546 amu, which of the two isotopes is most abundant? Explain your answer. The most abundant isotope is Cu-63 because it is closest to the mass of copper on the periodic table. Analyze the following chart and determine what elements are isotopes of the same element. Atom A Atom B Atom C Atom D #P 15 10 #N #E Mass 30 20 25

Average Atomic Mass Check this out!!! http://www.youtube.com/watch?v=xirPkCI1sMA&feature=related

Calculating Atomic Mass Isotope Mass Abundance 24Mg = 23.99 amu x 78.70/100 = 18.88 amu 25Mg = 24.99 amu x 10.13/100 = 2.531 amu 26Mg = 25.98 amu x 11.17/100 = 2.902 amu Atomic mass (average mass) Mg = 24.31 amu Mg 24.31 Basic Chemistry Copyright © 2011 Pearson Education, Inc.

Practice Activity Gallium is an element found in lasers used in compact disc players. In a sample of gallium, there is 60.11% of 69Ga (atomic mass 68.93) atoms and 39.89% of 71Ga (atomic mass 70.92) atoms. What is the atomic mass of gallium? Basic Chemistry Copyright © 2011 Pearson Education, Inc.

Solution 69Ga 68.93 amu x 60.11 = 41.43 amu (from 69Ga) 100 71Ga Atomic mass Ga = 69.72 amu 31 Ga 69.72 Basic Chemistry Copyright © 2011 Pearson Education, Inc.

Radioactive Decay =

Half-Life Half-life: Time it takes for an isotope to decay to its half amount.

Decay Curve

Drawing a Half-life Bar Graph Draw a bar graph representing the decay of Barium-139 if you start with a 20 g sample and it must decay to less than 2 g. The half-life of Barium-139 is 80 minutes. Bar Graph Representation and Percent Fraction Remaining Mass Mass in Grams Time passed (years) # of Half-life

Drawing a Half-life Bar Graph Solutions Graph Representation and Percent Fraction Remaining Mass Mass in Grams Time passed (years, min) # of Half-life 50% 25% 100% 12.5% 6.25%

Drawing a Half-life Bar Graph Solutions Graph Representation and Percent Fraction Remaining Mass 2/2 1/2 1/4 1/8 1/16 Mass in Grams Time passed (years, min) # of Half-life 50% 25% 100% 12.5% 6.25%

Drawing a Half-life Bar Graph Solutions Graph Representation and Percent Fraction Remaining Mass 2/2 1/2 1/4 1/8 1/16 Mass in Grams 20 g 10 g 5 g 2.5 g 1.25 g Time passed (years, min) # of Half-life 50% 25% 100% 12.5% 6.25%

Drawing a Half-life Bar Graph Solutions Graph Representation and Percent Fraction Remaining Mass 2/2 1/2 1/4 1/8 1/16 Mass in Grams 20 g 10 g 5 g 2.5 g 1.25 g Time passed (years, min) 0 min 80 min 160 min 240 min 320 min # of Half-life 50% 25% 100% 12.5% 6.25%

Drawing a Half-life Bar Graph Solutions Graph Representation and Percent Fraction Remaining Mass 2/2 1/2 1/4 1/8 1/16 Mass in Grams 20 g 10 g 5 g 2.5 g 1.25 g Time passed (years, min) 0 min 80 min 160 min 240 min 320 min # of Half-life 1 2 3 4 50% 25% 100% 12.5% 6.25%

Harnessing the Nucleus Nuclear Fission Nuclear Fusion *Chain reaction *High temperatures/Sun & Star *Huge amounts of energy produced *Greater energy produced *Nuclear power plants *Less radioactive waste formed *Impossible to create artificially

Final Reflection on Radiation…… * *