Ch Nuclear Chemistry

Discovery of Radioactivity Radioactivity was first observed in ______by the French scientist Henri Becquerel. He discovered that Uranium salts would “fog up” a photographic plate. In 1898, Marie Curie and her husband Pierre coined the term radiation and radioactivity and went on to discover several new elements: ___________ and ________. She went on to win 2 Nobel Prizes: 1903 in Physics & 1911 in Chemistry, but she died of ________ caused by radiation exposure in 1934 at the age of 66. Her husband died in 1906 after getting hit by a horse and buggy. Marie Curie 1896 Polonium Radium cancer

Nuclear Reactions Nuclear reactions involve the _________ instead of the ___________ as in a regular chemical reaction. The instability of the nucleus of a radioactive element causes the # of protons and neutrons to change. Some of the ______ can be converted into a tremendous amount of energy shown by a very famous equation: E=mc 2 Energy = (mass) x (speed of light) 2 c= 3.0 x 10 8 m/s nucleus electrons mass

Nuclear binding energy (BE) is the energy required to break up a nucleus into its component protons and neutrons. BE + 19F 9 1p n 9 10 Mass defect (∆m) = 9 x (p mass) + 10 x (n mass) – 19F mass E = mc2 ∆m (amu) = 9 x x – ∆m = amu = 2.636x10-28 kg BE = 2.636x10-28 kg x (3x108 m/sec)2 = 2.37 x 10-11J 23.2 When this atom forms, a tiny amount of matter is converted to energy Energy = mass(kg) x [speed of light ]2 Speed of light = c = 300,000,000 m/sec This may look small, but it means that when 19 g of flourine forms there is 14,000,000,000 kJ of energy released. That’s the same as burning 285,000 tons of coal!

kg Nuclear Reactions kg kg – ( ) = kg E=mc 2 E= x (3.0 x 10 8 ) 2 = 5.31 x Joules

What makes a nucleus stable or unstable? It depends on the p + and n o ratio. Z= Atomic # = p + A = Mass # = n o + p + “Nucleons” are just the particles in the nucleus. ex) 2 He A Z Element symbol 4

Chemical vs. Nuclear Reactions

Nuclear Reactions: Radiation Nuclear reactions release 3 main types of radiation: – (α) Alpha Particles … ________ nucleus (2 p + and 2 n 0 ) – (β) Beta Particles… high energy ___________ – (γ) Gamma Rays… high energy _________________ radiation helium electrons electromagnetic

How To Write Nuclear Particles --α Particles … helium nucleus (2 p + and 2 n 0 ) 2 He --β Particles… high energy electrons -1 e --γ Rays… high energy electromagnetic radiation 0 γ 0 γ -- Positrons…positive charged electrons 1 e -- Neutrons…neutrally charged particles in the nucleus that contributes to the mass of an atom 0 n

Balancing Nuclear Reactions In chemical reactions the elements stay the same. In nuclear reactions, the elements ________ but the mass #’s and atomic #’s are ___________. Alpha Emission Beta Emission change conserved

Alpha Decay

Beta Decay

Another type of nuclear reaction is “electron capture” where an atom “_________” one of its own electrons. absorbs

Positrons: They are just like an electron, but they have a (___) charge instead of a negative charge. +

Types of Decay--Summary

Nuclear Fission In fission, the nucleus _______ apart.(Fission is division.) Atom bombs and nuclear power plants use fission of U-235. splits

Nuclear Fission: Chain Reaction

Detecting Radiation When the argon gas is hit by a particle, it ionizes and produces a current…“click”.

Nuclear Power Currently about _____ nuclear power plants in the U.S. and about _____worldwide. _____ of the world’s energy comes from nuclear. There are ___ nuclear power plants in Illinois. The closest one to us is in _________ % 6 Clinton

Clinton, IL Nuclear Power Plant

1000 MegaWatt Power Plant Pollution Coal-Fired vs. Nuclear

Nuclear Power Plants Nuclear power plants use the heat of a controlled nuclear fission reaction to ______ water that makes steam which turns a _________ and that produces electricity. boil turbine

Nuclear Power Plant “Disasters” One possible type of reactor disaster is known as a __________. In such an accident, the fission reaction goes out of control, leading to the emission of great amounts of radiation. meltdown

In ______, a much worse disaster struck Russia's Chernobyl nuclear power plant. In this incident, a large amount of radiation escaped from the reactor. Hundreds of thousands of people were exposed to the radiation. Several _______ died within a few days. In the years to come, thousands more may die of cancers induced by the radiation.Chernobyl nuclear power plant 1986 dozen

Chernobyl Sarcophagus

Nuclear Fusion In Fusion, nuclei combine to form a _________ nucleus. When the p + and n 0 bind, this releases tremendous amounts of ________. Nuclear fusion occurs in the _____ and other stars. heavier energy sun

Spiderman 2—Tritium

Medicine imaging and tumor treatments Thyroid imaging using Tc-99 Uses of Nuclear Radiation

Food Irradiation Food can be irradiated with gamma rays from 60 Co or 137 Cs. Irradiated milk has a shelf life of __________without refrigeration. USDA has approved irradiation of _______ and eggs. 3 months meats

Isotope Half-Life Radiation Emitted Carbon-14 5,730 years  Radon days  Uranium x 108 years  Uranium x 109 years  Radiocarbon Dating--The radioactivity of a sample can be used to determine how _____ it is. Half-life: The time for ______ of the nuclei to decay. old half

Half-Life Graph

Half life practice problems Astatine has a half-life of about 400 minutes. If you started with 1000 mg of At, how much would you have after 20 hours? x 1 hour 60 min = 1200 mins 1200 mins / 400 mins = 20 hours 3 Which means “cut in half” 3 times 1000 mg / 2 = 500 mg / 2 = 250 mg/ 2 = 125 mg