4 forces of nature Weak force holds quarks together Force of Gravity Electrostatic force Strong force hold the + charges in the nucleus together

alphabetagamma Symbol 4 He, α 2 0 e, β 0 γ 0 SizeLargeSmallNo size Charge+2O charge SpeedSlowFastSpeed of light ShieldingPaper/skinMetal foil Inches lead IdentityHelium nucleus electronWave of energy

Sources of Radiation Background Cosmic radiation Earth Food People Flying Medical tests Cigarettes

Uses in medicine Tracer I-131 Irradiation therapy Cs-137

Ionizing radiation How much is safe? Biological damage Radiation effects

Nuclear Reactions Radioactive Decay Nuclear bombardment (Transmutation) Fission Fusion

Radioactive Decay Spontaneous(Natural) emission of alpha, beta gamma Other radiation

Radioactive decay Alpha emission Parent  alpha + daughter + gamma

Radioactive decay Beta emission Parent  beta + daughter + gamma

Radon T ½ = 3 days Gas Daughter is a solid

Lab: Half-life Purpose: To simulate radioactive decay Reaction: Parent  Daughter + radioactivity M  no M Data table: # half-lives # decayed# undecayed O(no M) 0 (M)40 Each shake will simulate 1 half life.

Half-life The time for ½ the amount of a parent to decay to a daughter Set up a chart # half lives TimeAmount 0 0

Try this! N-13 emits beta. If 2.0g decay and the half life is T 1/2 = 10 min a.How long is 4 half lives? b.How many grams remain? c.Write the decay reaction.

Try another Manganese-56 is a beta emitter with T 1/2 =2.6 hr. What is the mass of a 10 g sample after 10.4 hrs? How many half lives is this? Write the radioactive decay reaction.

More Iron-59 has a T ½ =45 days. If 2.0 g decay How many days does it take until.25g remain? W

Try another Manganese-56 is a beta emitter with T 1/2 =2.6 hr. What is the mass of a 10 g sample after 10.4 hrs? How many half lives is this? Write the radioactive decay reaction

More What is the half life of I-131 when a 10 g sample decays to.625 g in 80 days?

Nuclear bombardment transmutation Emission of radiation after a nucleus is hit by a particle causing it to change to another element

Nuclear bombardment 1919 Rutherford N-14 + alpha  proton + ? 1932 Chadwick Be-9 + alpha  carbon-12 + ? 1934 Curie Al–27 + alpha  P-30 + ? P-30  Si-30 + ?

Particle Accelerators Cyclotron Synchrotron Linear accelerator Super conduction supercollider

Transuranium elements Elements with atomic number greater than 92

C-14 dating N-14 + n  C-14 + Proton in air C-14 + O 2  CO we breathe it in C-14  N-14 + beta Know what is in living Measure what is in dead Know the T ½ Do half life problem to calculate time

Problem The living organism has 15g C-14 The half life is 5,730 year If the dead organism has.95g of C-14, how long has it been dead?

Nuclear Fission splitting the atom WWII Hahn, Strassman, Meitner Manhattan Project Los Alomos New Mexico Fat Man, Little Boy U N  Ba Kr N + Energy

E=mc 2 E=m(3.00x10 8 m/sec) 2 Law of Conservation of Matter is only valid for chemical reaction. In nuclear reactions the mass is changed into lots of energy

Nuclear Binding Energy He nucleus amu, what is binding energy? 1 proton = amu 1 neutron = amu E= J= 1 1 amu = 1.66 x g

Nuclear Reactors steam is made to generate electricity FuelU-235 Moderatorslows down neutrons Control rodsabsorb neutrons Shieldingconcrete Coolantwater Critical mass – mass needed to keep a nuclear reaction going Chain reaction – reaction where a neutron starts the reaction and is produced in the reaction.

Chain reaction

Nuclear waste High level spent fuel defense waste Low level Protective clothing Medical radioisotopes Air filters

Nuclear Fission splitting the atom WWII Hahn, Strassman, Meitner U Neutron  2 medium + 3 neutrons + Energy See overhead

Fusion

Fusion ( joining parts) See overhead Naturally in sun Research in California Requirements 40,000,000 o C high pressure plasma container electricity