CHAPTER 25: NUCLEAR CHEMISTRY Mrs. Brayfield
CHEMICAL VS. NUCLEAR When you hear the word nuclear, what do you think of? What makes nuclear reactions different from chemical reactions? The speed of nuclear reactions cannot be controlled No energy is required by nuclear reactions for decay to start
NUCLEAR REACTIONS Nuclear reactions involve unstable isotopes What is an isotope? An isotope is an atom of the same element that have the same atomic number but have different atomic masses due to a different number of neutrons
REMEMBER... Remember that the atomic mass is the number of neutrons plus the number of protons A is the atomic mass Z is the number of protons A ZX An example is: 11 6C where Carbon has a mass of 11, 5 neutrons, and 6 protons
Number of Neutrons THE CHART OF THE NUCLIDES Number of Protons
THE CHART OF THE NUCLIDES That black line is called the band of stability This is where atoms have Z N very close to one This means that these atoms are stable This is why we have unstable isotopes (not on this black line) The process of converting one atom of an element into another element is called transmutation
THE CHART OF THE NUCLIDES The chart of the nuclides plots all known isotopes The elements with atomic number HIGHER than 92 are called the transuranium elements ALL transuranium elements are radioactive
NUCLEAR DECAY All nuclear decay reactions can be modeled by the SAME equation. That equation is called half-life
HALF-LIFE What is half-life? Half-life is the time required for one-half of the nuclei of a radioisotope sample to decay to products What is a radioisotope? A radioisotope is an unstable isotope
QUICK ACTIVITY Safety: DO NOT eat too quickly that you choke! Grab a worksheet and a twizzler!
HALF-LIFE All nuclear decay reactions can be modeled by the SAME equation. A = A 0 ( 1 2) n Where: A = remaining amount A 0 = initial amount n = the number of half-lives
ALPHA DECAY Alpha decay is where a nucleus emits a helium nucleus with 2 protons and 2 neutrons Symbol: 4 4 2He or 2 α 238 4 234 He + Th 92U 2 90
BETA DECAY Beta decay is where the nucleus emits a beta particle (one electron) Symbol: 1 0 β or 1 0 e 228 88Ra 1 0 228 β + 89Ac
GAMMA DECAY Gamma decay is where an excited nucleus emits a gamma ray to de-excite the nucleus 0 Symbol: 0 γ 240 94 Pu 240 0 0 γ + 94Pu
NEUTRON DECAY (NEUTRON EMISSION) Neutron decay is where the nucleus emits a neutron 1 Symbol: 0 n 13 4Be 1 12 0 n + 4Be
SHIELDING FOR RADIATION Alpha particle Paper Beta particle Piece of wood Gamma particle 1 meter of concrete
MYSTERIUM: 15 5My How many protons? How many neutrons? Alpha Decay: Beta Decay:
EXAMPLES What type of decay is this? 40 40 Ca + e K 19 20 1 0 60 Co 60 0 27 27Co + 0 γ 210 4 206 86Rn 2 α + 84Po
MORE EXAMPLES Balance these reactions: 13 12 4Be 4Be + 14 6 C 1 0 β + 237 4 2He + 93Np
BEFORE WE CONTINUE How much TNT is the equivalence of one of the bombs dropped by the US in Japan?
BACKGROUND Binding energy Binding energy is the energy that holds the nucleus together How are the sun and a power plant similar? They both produce energy!
FISSION Fission is where an unstable isotope, when hit by a neutron, decays into two atoms and three neutrons This process is called a chain reaction 235 1 143 92U + 0 n Xe + 38 90 1 Sr + 3 0 n 54
FUSION Fusion is where two atoms, at high heat, combine to produce one larger atom and one neutron This is the process that fuels the sun 3 2 4 1 1H + 1 H 2He + 0 n
FISSION POWER REACTOR
PURDUE S NUCLEAR REACTOR (100W)
FUSION POWER REACTOR
FISSION POWER REACTOR
PROJECT To wrap up this chapter, you will pick a partner to research one nuclear application You will pick a topic and then take a pro or con stance to that topic Topics may include: Nuclear medicine Weapons Reactors Sterilization
PROJECT You will get two days of class time to work on this project Presentations will be Friday March 13 th (red day) and Monday March 17 th (white day) You need some visual component to your presentation i.e. a video, pamphlet, poster, etc
PROJECT EVERYONE in the group must speak during their presentation Graded based on rubric Questions???