2. Nuclear Notes: StructureandRadioactivity Online @ redwood.org/stewart

3. I. Structure of the Atom RecognizeMe? Draw Me!

4. II. Periodic Table--p. 346 in GS Atomic # vs. Atomic Mass A.Atomic No. = p = number of protons (p) in the nucleus B.Atomic mass = p + n = the sum of the mass of protons (p), neutrons (n) (and electrons (e)) but e have no significant mass). 1. # n = atomic mass - atomic no. 2. # n is not always the same! isotopes - atoms of the same element (same number of protons) that have different number of neutrons

5. III. Radioactivity A.The emission of particles due to the breakdown of unstable atomic nuclei (radioisotopes). B. Isotopes and large atoms are unstable and will break apart. Nucleus is decomposing: losing mass/particles, and/or energy New, lighter atoms are formed, releasing radiation in the process. New, lighter atoms are formed, releasing radiation in the process. Decomposition continues until enough mass has been lost making the atom stable again. Decomposition continues until enough mass has been lost making the atom stable again. a.k.a. radiation ThereforeTherefore Unstable = radioactive End, Part 1

6. IV. Radiation Energy that is radiated or transmitted in the form of rays,waves, or particles.

7. IV. Types of Radiation These 3 types of radiation are all naturally-occurring. A.Alpha (  ) particle (Helium atom): naturally-occurring. 1.Descriptoin: 2 protons lost, and…2 neutrons lost 2. this makes a Positive charge (of +2); Mass of 4 3. So… 3. So…The atomic # of decaying atom DECREASES by 2 and the mass DECREASES by 4 4. 4. Shielded by: paper and dead skin    Symbol Sum of mass numbers (p + n) and sum of atomic numbers (p) is the SAME on both sides of equation.  Helium atom!

8. B.Beta (  ) particle (electron): naturally-occurring. 1. Description: One neutron is converted into a proton and an electron. 2. The electron is lost: negative charge (-1) No measurable mass lost. 3. 3. The atomic # of the decaying atom INCREASES by 1 and the mass does not change. 4. Shielded by: plastic, glass and aluminum    Symbol Sum of mass numbers (p + n) and sum of atomic numbers (p) is the SAME on both sides of equation.    ENERGY

9. C.Gamma (  ) radiation: naturally-occurring. 1. Description: High energy photon is released. ENERGY given off! Virtually all nuclear reactions have this (including naturally and non- naturally occurring reactions) 2. No charge. No measurable mass lost. 3. 3. The atomic number and mass of the decaying atom do not change.  Powerful and dangerous.  Shielded by: thick lead and concrete. Powerful and dangerous. Symbol    Sum of mass numbers (p + n) and sum of atomic numbers (p) is the SAME on both sides of equation. Where does the gamma radiation come from? Mass is converted into energy (more on this later). ENERGY

10. Naturally-occurring Summary of Naturally-occurring Radiation

11. V. Nuclear Fission A.Definition of Fission: the splitting of a large atom into smaller fragments (particles and/or smaller atoms) This is the nuclear reaction the world currently uses to generate any and all usable nuclear energy--not naturally occurring. B.Process A large atom is struck by a single neutron. Smaller atoms are created. Energy and neutrons are released Uranium: the most common large atom used: Uranium (U) - 235 (atomic number 92) Question: How many neutrons does U-235 have? Answer: 235 - 92 = 143 Sum of mass numbers (p + n) and sum of atomic numbers (p) is the SAME on both sides of equation.  ENERGY

13. VI. Nuclear Fusion A.Definition of Fusion: the combining of 2 smaller atoms into a larger atom--not naturally occurring on earth (but happens on sun and stars). B.Only possible with isotopes of Hydrogen: Deuterium and Tritium.  Trit  He Neutron  ENERGY

14. Summary of Non-naturally occurring Nuclear Energy End, Part 2   ENERGY ENERGY

15. VII. Where does the kinetic energy in a nuclear reaction come from? The mass of protons and neutrons varies depending on what atom they are in. The mass of protons and neutrons before a nuclear reaction is GREATER than after the reaction. Fission Fusion

16. VII. Where does the kinetic energy in a nuclear reaction come from? The mass is TRANSFORMED into kinetic energy according to Einstein’s famous equation: E = mc 2 -- mass IS energy! Energy equals mass times the speed of light squared. The speed of light is 300,000 kilometers per second, so even a very small mass produces a LOT of energy !

17. VIII. Energy Evolved A.FISSION: 1 gram of U-235 evolves 2x10 7 Cal/g (20 million Cal/g)* * which equals the heat from 30 tons of TNT * which equals the heat from 30 tons of TNT Versus 1 gram of oil = 9.8 Cal 1 gram of oil = 9.8 Cal 1 gram of Uranium = 20,000,000 Cal 1 gram of Uranium = 20,000,000 Cal B. The energy released in nuclear FUSION is about 7 times greater than the energy released in the fission of Uranium. B. The energy released in nuclear FUSION is about 7 times greater than the energy released in the fission of Uranium. 10 grams of Deuterium which can be extracted from 500 liters of water could produce enough fuel for the lifetime electricity needs of an average person in an industrialized country.

18. IX. Advantages and Disadvantages of Using Nuclear Fuel A.Advantages: Fuels are plentiful. If shielded properly, it is inherently safe since any malfunction results in a rapid shutdown. No atmospheric pollution leading to acid rain or global warming. Small amounts of mass yield high amounts of energy. B.Disadvantages: What are some disadvantages of using Nuclear Fuel to generate electricity? End (Part 3)