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Learn how to balance natural decay and artificial transmutation equations, understand conservation laws in nuclear reactions, and explore the relationship with the periodic table.
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Williamsburg High School for Architecture and Design Mr. Quinn and Ms. Tom 9/30/13 Balancing Nuclear Equations
Aim How do I balance natural decay equations?
Types of Equations? • 4 = 2 + 2 • Y = mx + b • 146C → 147N + 0-1e
Mass Number A X Element Symbol Z Atomic Number particle proton neutron electron positron 1p 1H 0 0 4 4He 1n 0e 0e or or or or 0 -1 +1 2 2 1 1 -1 +1 Atomic number (Z) = number of protons in nucleus Mass number (A) = number of protons + number of neutrons = atomic number (Z) + number of neutrons A 1 1 0 0 4 1 0 -1 +1 2 Z 23.1
1n 1n 235 138 96 + + + 2 U Cs Rb 92 55 37 0 0 Balancing Nuclear Equations Conserve mass number (A). The sum of protons plus neutrons in the products must equal the sum of protons plus neutrons in the reactants. 235 + 1 = 138 + 96 + 2x1
235 138 96 + 1n U + 2 + 1n Cs Rb 92 0 55 37 0 Balancing Nuclear Equations 2. Conserve atomic number (Z) or nuclear charge. The sum of nuclear charges in the products must equal the sum of nuclear charges in the reactants. 92 + 0 = 55 + 37 + 2x0
4 4He or alpha particle - 2 2 212Po 4He + AX 2 Z 84 212Po 4He + 208Pb 2 82 84 212Po decays by alpha emission. Write the balanced nuclear equation for the decay of 212Po. 212 = 4 + A A = 208 84 = 2 + Z Z = 82 23.1
Aim How do I balance artificial transmutation equations?
II. Nuclear Transmutations • Nuclear reactions that are induced in a way that nucleus is struck by a neutron or by another nucleus (nuclear bombardment) • Positive ion bombardment - alpha particle is the most commonly used positive ion - uses accelerators Examples: 147 N + 42 He → 178 O + 11 H 94 Be + 42 He → 126 C + 10n
II. Nuclear Transmutations Neutron bombardment - neutron is bombarded to a nucleus to form a new nucleus - most commonly used in the transmutation to form synthetic isotopes because neutron are neutral, they are not repelled by nucleus Example: 5826 Fe + 10 n → 5926 Fe → 5927 Co + 0-1 e
4He 1n 239 242 + + Pu Cm 94 96 2 0 1n 238 239 + U U 92 92 0 0 e 239 239 + + 0-1 e Pu Np 94 93 -1 14N 5 1n 238 247 + + U Es 92 99 7 0 Transuranium elements • Element with atomic numbers above 92 • Produced using artificial transmutations, either by: • alpha bombardment • neutron bombardment • bombardment from other nuclei Examples: a. b. c.