RADIATION AND NUCLEAR SCIENCE 10 EARTH SCIENCE ENERGY

RADIATION AND NUCLEAR SCIENCE 10 EARTH SCIENCE ENERGY

LESSON 1: RADIATION

RADIATION Radiation is energy given off by matter in the form of electromagnetic rays or high-speed particles. Radiation can be nonionizing or ionizing depending on how it affects matter. Ionizing radiation is harmful.

RADIATION SOURCES NATURAL SOURCES INCLUDE: Cosmic radiation (video) Sun radioactive isotopes in soil, air and water HUMAN INTRODUCED SOURCES INCLUDE: Electronics Medical X-Rays Medical Isotope exposure Nuclear power Artificial radiation

PHYSICAL FORMS OF RADIATION Particles Radiation in the form of high - speed particles comes from nuclear decaying atoms; atoms that undergo nuclear change. These particles can be alpha particles or beta particles. These can be high - speed neutrons

PHYSICAL FORMS OF RADIATION Waves Radiation in the form of waves or rays has no weight and is pure energy. This form of radiation known as electromagnetic radiation. These harmful waves include gamma rays, x-rays, and cosmic rays.

ELECTROMAGNETIC SPECTRUM The electromagnetic spectrum is the range of all types of electromagnetic radiation: radio waves Microwaves Infrared Visible light UV X-ray Gamma rays

ELECTROMAGNETIC SPECTRUM Each type of electromagnetic radiation can be represented by frequency (Hertz), wavelength (meters) and energy (electric Volts). The differences in these characteristics creates specialized properties for the each type of electromagnetic radiation.

WAVELENGTH AND FREQUENCY Wavelength - the distance between successive crests of a wave, especially points in a sound wave or electromagnetic wave. Frequency - the number of wave crests passing by a given point in one second. c=λν where λ is the wavelength, ν is the frequency and c is the speed of light. Speed of light (c) = 300,000,000m/s Note: The higher the frequency, the shorter the wavelength. Light would travel 7.5 times around the Earth in one second All electromagnetic rays travel at the speed of light in a vacuum 300,000Km/s 3X10 8 m/s (λ)

NONIONIZING RADIATION VS. IONIZING RADIATION

IONIZING RADIATION Ionizing radiation that carries enough energy to liberate electrons from atoms or molecules, therefore ionizing them. Ionizing radiation can be subatomic particles or high-energy electromagnetic waves. Subatomic Particles: Alpha particles Beta particles High energy Neutron Electromagnetic waves: UV waves X-Rays Gamma Rays Ionizing radiation is harmful.

ALPHA PARTICLES Charged particle that resembles a Helium nuclei Emitted naturally decaying atoms, such as uranium, thorium, radium Emitted from manmade decaying atoms, such as plutonium and americium Used in smoke detectors Slow moving and easily stopped by a sheet of paper, skin, or even a few inches of air Dangerous if they are inhaled or swallowed, but external exposure generally does not pose a danger.

BETA PARTICLES 0 0 β or -1-1 e Charged particles that are similar to electrons emitted from naturally occurring materials, such as, strontium-90 Such beta emitters are used in medical applications, such as treating eye disease. Lighter than alpha particles Thin sheet of metal or plastic or a block of wood can stop beta particles

NEUTRON high-speed nuclear particles Exceptional ability to penetrate other materials Neutron activation: the ability to create unstable nuclei of atoms Radioactive sources created from neutron activation include items used in medical, academic, and industrial applications (including oil exploration). Concrete or water can block them neutron radiation primarily occurs inside a nuclear reactor, where effective shielding occurs. 1 0n

IONIZING RADIATION - WAVES This from of ionizing energy can strip electrons off of atoms or even destabilize the nucleus of an atom. These waves consist of high in energy, high frequencies and small wavelengths. Can often penetrated other materials but do not make them radioactive. Can be stopped by lead or concrete.

IONIZING RADIATION - WAVE TYPES X-Rays: used to provide static images of body parts (such as teeth and bones), and are also used in industry to find defects in welds. Gamma Rays: cobalt 60 releases gamma radiation it is used to treat cancer and sterilize medical instruments. Cosmic Radiation: the suns and stars emit a constant stream of cosmic radiation, on Earth we are protected by the magnetic field.

NONIONIZING RADIATION Nonionizing radiation refers to the low energy portion of the electromagnetic spectrum. Radio waves, microwaves and infrared do not have enough energy to ionize atoms or molecules; they cannot completely remove an electron. Extremely low-frequency (ELF) waves that are produced by electrical power lines and wiring are also nonionizing radiation.

LIGHT SPECTRUM VISIBLE LIGHT Visible light is considered nonionizing radiation. However, it can excite electrons to a higher energy state without producing an ion. Visible light has photochemical effects. 380 750 nm (visible from 400-700nm) Electron Excitation

CONTINUOUS LIGHT SPECTRUM VS. DISCRETE Continuous Spectrum: LIGHT SPECTRUM A beam of white light that shows a continuous spectrum of all of the physical quantities (waves or energy) for its colors of light. Dispersing light through a prism can show all of its colors.

CONTINUOUS LIGHT SPECTRUM VS. DISCRETE LIGHT SPECTRUM Discrete Spectrum: A physical quantity (wave or energy) is said to have a discrete spectrum if it takes only distinct values, with positive gaps between one value and the next. Spectral lines are often used to identify atoms and molecules.

DISCRETE LIGHT SPECTRUM: ABSORPTION VS. EMISSION SPECTRUM A given atom will absorb and emit the SAME frequencies of electromagnetic (E-M) radiation. These frequencies match the energy levels of the atom Absorption Spectrums: Light passes through a cloud of gas. Black bands are present in the spectrum where energy for those wavelengths has been absorbed by the gas. All other light wavelengths are visible. Also called DARK-LINE SPECTRUM

DISCRETE LIGHT SPECTRUM: ABSORPTION VS. EMISSION SPECTRUM A given atom will absorb and emit the SAME frequencies of electromagnetic (E- M) radiation. These frequencies match the energy levels of the atom. Emission Spectrum: Observation of the gas not the star. Color bands represent the emission of light given off by the gas in the cloud. Also called BRIGHT-LINE SPECTRUM

UNDERSTANDING THE STARS Stars are large celestial bodies of gas that emit electromagnetic energy This energy comes from Nuclear changes in the atoms of the star, called Nuclear Fusion Nuclear Fusion is the combination of light atomic nuclei into heavier atomic nuclei

UNDERSTANDING THE STARS Astronomers study the stars by looking at the light emitted The light runs through a spectrograph that separated light into a spectrum The stars spectrum reveals its composition and temperature.

UNDERSTANDING THE STARS COMPOSITION OF THE STARS By studying the light spectrum of the stars, scientists have learned that: Hydrogen is the most common element in the stars Helium is the second most common element in the stars Carbon, oxygen and nitrogen make up less than 1% of stars

UNDERSTANDING THE STARS TEMPERATURE OF THE STARS The color of the star indicates its temperature Stars range from 2,800 C to 24,000 C and hotter The color of a star related to the energy of the star: Blue - 35,000 C Yellow (the Sun) - 5,550 C Red 3,000 C

HOMEWORK Radiation worksheet Tomorrow - Spectrum Lab

LESSON 2: RADIOACTIVE DECAY AND NUCLEAR ENERGY

ISOTOPES 39 K, 40 K, 41 K 19 19 19 Are different atoms of the same element, with a different number of neutrons. changing the # of neutrons changes the mass number Remember: mass # = # protons + # neutrons isotopes still have the same number of protons and the same element symbol Atomic Mass (the decimal # s) Atomic mass = average of the mass numbers for all isotopes of an element.

REPRESENTING ISOTOPES Isotopes are written two ways with the mass number at the end Ex. Potassium 40 With its chemical symbol Ex. 40 19K Mass number Atomic number 39 40 41 19K, 19K, 19K 19 19 19 20 21 22 19 19 19

RADIOACTIVE DECAY Can result in new atoms forming. Radioactivity results from having an unstable nucleus. Radioactive Decay = when nuclei break apart + release energy from the nucleus. Radioactive decay continues until a stable element forms. An element may have isotopes that are radioactive called radioisotopes Ex. carbon-12, carbon-13 and carbon-14 (only C-14 is radioactive)

RADIOACTIVE DECAY OF URANIUM - 238

Rutherford identified three types of radiation using an electric field. Positive alpha particles were attracted to the negative plate. Negative beta particles were attracted to the positive plate. Neutral gamma particles did not move towards any plate.

Alpha Decay 4 α or 4 He 2 2 Example: the alpha decay of Radium - 226 Ra Rn + α or Ra Rn + He 226 222 4 226 222 4 88 86 2 88 86 2

BETA RADIATION: Beta particles are represented by the symbols 0 β or 0 e -1-1 electrons are very tiny, so beta particles are assigned a mass of 0. one electron gives a beta particle a charge of 1 It takes a thin sheet of aluminum foil to stop a beta particle.

Beta Decay β or 0 0-1 -1 e Beta decay occurs when a neutron changes into a proton and an electron. The proton stays in the nucleus, and the electron is released. Example: The beta decay of iodine - 131 I Xe + 131 131 0 53 54 1 or I Xe + β 131 131 0 53 54 1 e

GAMMA RADIATION: Gamma radiation, γ, is a ray of high energy, short-wavelength radiation. has no charge and no mass. is the highest energy form of electromagnetic radiation. Gamma decay results from energy being released from a high-energy nucleus. Ni * Ni + γ 60 60 0 28 28 0 Shows unstable nucleus for gamma decay

Often, other kinds of radioactive decay will also release gamma radiation. Uranium-238 decays into an alpha particle and also releases gamma rays. 238 U 234 Th + 4 He + 2 γ 92 90 2

NUCLEAR REACTIONS: Nuclear reactions are different than chemical reactions Chemical Reactions Mass is conserved (doesn t change) Small energy changes No changes in the nuclei Nuclear Reactions Small changes in mass Huge energy changes protons, neutrons, electrons and gamma rays can be lost or gained

SYMBOLS TO REMEMBER:

NUCLEAR REACTIONS Two types: Fission = the splitting of nuclei Fusion = the joining of nuclei (they fuse together) Both reactions involve extremely large amounts of energy Albert Einstein s equation E = mc 2 illustrates the energy found in even small amounts of matter

1. NUCLEAR FISSION: Nuclear fission is the splitting of one heavy nucleus into two or more smaller nuclei, as well as some sub-atomic particles and energy. A heavy nucleus is usually unstable, due to many positive protons pushing apart. When fission occurs: 1.Energy is produced. 2.More neutrons are given off.

2. NUCLEAR FUSION joining of two light nuclei into one heavier nucleus. In the core of the Sun, two hydrogen nuclei join under tremendous heat and pressure to form a helium nucleus. When the helium atom is formed, huge amounts of energy are released. The fusion of hydrogen nuclei

NUCLEAR EQUATIONS: are written like chemical equations, but represent changes in the nucleus of atoms. Chemical equations represent changes in the position of atoms, not changes to the atoms themselves. Remember: 1. The sum of the mass numbers on each side of the equation should equal. 2. The sum of the charges on each side of the equation should equal.

FUSION IN THE STARS Nuclear fusion produces most of the stars energy and occurs in three steps: Step 1: Two Hydrogen nuclei (protons) collide and fuse One proton becomes a positron and is emitted resulting in the production of a neutron One proton and one neutron Step 2: A proton collides with the proton-neutron pair and produces a rare Helium nuclei Step 3: Collision between two of these nuclei collide and fuse emitting two protons and forming a Helium nuclei with two protons and two neutrons. At every step energy is released thus the mass is converted into energy.

MASS CHANGING TO ENERGY The sun is changing about 4 million tons of matter into energy every second. 26 Mev of energy is released in the last step of fusion. 240,000,000,000 fusion reactions need to occur to produce 1 Joule Neutrinos are emitted from the sun during Fusion and arrive at the Earth 8 minutes after they leave the Sun. Studies of Neutrinos prove that hydrogen fusion is taking place in the Sun. Albert Einstein s equation E = mc 2 illustrates the energy found in even small amounts of matter

HOMEWORK Radioactive Decay and Nuclear Energy

LESSON 3: TECHNOLOGY AND IMPLICATIONS

TELESCOPES Telescopes: are designed to observe space detect electromagnetic wavelengths and concentrate it for better observation optical telescopes observe visible light, they are either reflecting or refracting Invisible electromagnetic radiation can be observed with telescopes. However, the atmosphere acts as a shield against these waves, there for telescopes outside of the atmosphere are most effective. Fermi Gamma Ray Telescope Radio Telescope

OPTICAL TELESCOPE REFRACTION TELESCOPE Lenses are used to bend light. Refraction is the bending of light. Light passes through the lens to a focal point and is magnified by an eyepiece. Disadvantage: Different wavelengths of light focus differently, that is, if an object is in focus in red light than it wont focus in blue light. Difficult to build large lenses, the amount of light collected from distant objects is limited by the size of the objective lens

OPTICAL TELESCOPE REFLECTION TELESCOPE Mirrors are used to gather distant light and focus it.

INVISIBLE ELECTROMAGNETIC RADIATION TELESCOPE

RADIOISOTOPE THERMOELECTRIC GENERATORS (RTGS)

SUBMARINES

NUCLEAR ENERGY

INDUCED NUCLEAR REACTIONS Scientists can also force ( = induce) nuclear reactions by smashing nuclei with alpha, beta and gamma radiation to make the nuclei unstable 4 α 14 17 1 2 7 8 1 + N O + p or He + N O + H 4 14 17 1 2 7 8 1

INDUCED NUCLEAR FISSION OF URANIUM-235 is the origin of nuclear power and nuclear bombs. 1 0n A neutron,, crashes into an atom of stable uranium-235 to create unstable uranium-236, which then decays. After several steps, atoms of krypton and barium are formed, along with the release of 3 neutrons and huge quantities of energy.

CHAIN REACTIONS: The neutrons released in the induced reaction can then trigger more reactions on other uranium-235 atoms causing a CHAIN REACTION

A chain reaction can quickly get out of control materials that absorb some neutrons can help to control the chain reaction. Nuclear reactors have complex systems to ensure the chain reaction stays at safe levels. An uncontrolled chain reaction can result in the release of excess energy as harmful radiation It is on this concept that nuclear bombs are created. Nuclear meltdown occurs if the chain reactions cannot be controlled

INDUCED NUCLEAR FISSION Neutrons are used to make nuclei unstable It is much easier to crash a neutral neutron than a positive proton into a nucleus to release energy.

OTHER APPLICATIONS AND IMPACTS OF RADIATION

COMMERCIAL APPLICATIONS

DAILY LIFE

RADIATION SHIELDING

ENVIRONMENTAL AND HEALTH EFFECTS What is a millisievert? For ionising radiation (X-rays, gamma-rays, electrons, neutrons etc.) the quantity of absorbed energy is called a "dose" and is measured in sieverts (Sv). A sievert is a very large and extremely unusual dose so more often we talk about thousandths of a sievert - a millisievert. Ionising radiation can be found in soils, in our air and water, and in us. Because it occurs in our natural environment, we encounter it every day through the food we eat, the water we drink, and the air we breathe. It is also in building materials and items we commonly use. Public Health England and its predecessor organisations have calculated the exposure of the UK population from naturally occurring and artificial sources of ionising radiation periodically since 1974.

Table 20.4 The Effects of a Single Radiation Dose on a 70 kg Human Dose (rem) Symptoms/Effects < 5 no observable effect 5 20 possible chromosomal damage 20 100 temporary reduction in white blood cell count 50 100 temporary sterility in men (up to a year) mild radiation sickness, vomiting, diarrhea, fatigue; 100 200 immune system suppressed; bone growth in children retarded > 300 permanent sterility in women fatal to 50% within 30 days; destruction of bone > 500 marrow and intestine > 3000 fatal within hours

MEASURING RADIATION

RADIATION AND NUCLEAR ENERGY REVIEW