Chapter 22 notesChapter 22 notes

Types of nuclear reactionsTypes of nuclear reactions

Fission- splitting of nucleus- nuclear Fission- splitting of nucleus- nuclear wastewaste

Fusion- nuclei can fuse together-no Fusion- nuclei can fuse together-no nuclear waste, but need 100 million nuclear waste, but need 100 million degrees C to make reaction happendegrees C to make reaction happen

Nuclear vs. Chemical reactionsNuclear vs. Chemical reactions

chemicalchemical nuclearnuclear

Part of atom Part of atom involved?involved?

Valence eValence e-- Protons and Protons and neutronsneutrons

How reaction is How reaction is started?started?

Atoms in close Atoms in close proximity with high proximity with high temp, pressure, temp, pressure, catalysts, or catalysts, or concentrations of concentrations of reactantsreactants

High temperature or High temperature or bombard with high-bombard with high-speed particlesspeed particles

Outcome of rxnOutcome of rxn Ionic or covalent Ionic or covalent bondsbonds

# protons or # protons or neutrons changesneutrons changes

Amt of energy Amt of energy released or released or absorbedabsorbed

Small Small HugeHuge

ExamplesExamples Digestion, making Digestion, making medicines, cleaning medicines, cleaning productsproducts

Nuclear energy, X-Nuclear energy, X-rays, cancer rays, cancer treatment, the suntreatment, the sun

Forces in nucleusForces in nucleus

Strong nuclear forces overcomes repelling Strong nuclear forces overcomes repelling force of protons to keep nucleus togetherforce of protons to keep nucleus together

This force attracts every proton and This force attracts every proton and neutron to each other (stronger than neutron to each other (stronger than electromagnetic repelling force)electromagnetic repelling force)

To keep nucleus together in heavier To keep nucleus together in heavier atoms, need more neutrons than protons atoms, need more neutrons than protons to overcome repelling forceto overcome repelling force

However past 83 p= strong nuclear force However past 83 p= strong nuclear force is not enough to keep atom together- is not enough to keep atom together- unstableunstable

Radioactivity Radioactivity

Nucleus emits particles or energyNucleus emits particles or energy Ex- U-238 decays eventually to Pb-206 (5-Ex- U-238 decays eventually to Pb-206 (5-

billion year process)billion year process) 3 types of radioactive decay3 types of radioactive decay

Alpha- helium atom released from unstable Alpha- helium atom released from unstable nucleus (2p and 2n)nucleus (2p and 2n)

Beta- neutron splits into a proton and electronBeta- neutron splits into a proton and electron Gamma- release of high energy, radiation from Gamma- release of high energy, radiation from

nucleus (shorter wavelength than X-rays)nucleus (shorter wavelength than X-rays)

Nuclear powerNuclear power

Sun power is nuclear power (heat Sun power is nuclear power (heat generated from fusion reactions)generated from fusion reactions)

Nuclear reactors- use fission to Nuclear reactors- use fission to produce steam to run turbines that produce steam to run turbines that generate electricitygenerate electricity

Nuclear wasteNuclear waste

Whereas coal and fossil fuel burning Whereas coal and fossil fuel burning contributes to global warming, nuclear contributes to global warming, nuclear reactors produce nuclear wastereactors produce nuclear waste

Waste is decaying nuclear atoms which Waste is decaying nuclear atoms which give off radiation as they decaygive off radiation as they decay

½ time it takes a sample of a radioactive ½ time it takes a sample of a radioactive element to decay halfwayelement to decay halfway

Most radioactive elements have long ½ Most radioactive elements have long ½ liveslives

Nuclear reactors- use uranium- long ½ lifeNuclear reactors- use uranium- long ½ life

Nuclear Waste/reactors Nuclear Waste/reactors continuedcontinued

How is the waste stored? How is the waste stored? Controversial issue!Controversial issue! Right now stored in containers meant to Right now stored in containers meant to

last 100yearslast 100years Proposal is to store in Proposal is to store in Yucca Yucca MtnMtn, , NevadaNevada

US- 20% energy from nuclear fission- US- 20% energy from nuclear fission- France 75%- Sweden and Belgium France 75%- Sweden and Belgium 50% or more50% or more

Nuclear reactions in scienceNuclear reactions in science

Use radioactive isotopes for medical Use radioactive isotopes for medical teststests

Use radioactive isotopes to trace Use radioactive isotopes to trace underground water suppliesunderground water supplies

Nuclear reactions used to sterilize Nuclear reactions used to sterilize packaged foodspackaged foods

Can predict age of fossils using Can predict age of fossils using radioactive isotopes radioactive isotopes

Marie Curie- what were her contributionsMarie Curie- what were her contributions

Protection against radiationProtection against radiation

Alpha particles- blocked by a sheet of Alpha particles- blocked by a sheet of paperpaper

Beta particles- clothing or wood Beta particles- clothing or wood Gamma- most dangerous need lead Gamma- most dangerous need lead

or concrete to block theseor concrete to block these