5.3.1 THE NUCLEAR ATOM

Describe the set up of the alpha scattering experiment

source/ gold foil/ moveable detector/ 2+ trajectories/ vacuum

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Describe the results of the alpha scattering experiment

most particles little or any deflection/ large deflection of very few (more that 90)/ elastic scattering/ alpha particle repelled by + nucelsu

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what were rutherford's conclusions from the alpha scattering experiment?

most particles went straight through - atom mostly empty space/ some alpha ps deflected more than 90 - centre of atom must be tiny but dense/ A particles repelled - nucleus must be +/ atoms neutral overall - electrons must be on the outside of atoms

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Define nucleon number

total sum of protons and neutrons in the nucleus/

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Define proton number

number of protons found in the nucleus

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What is the diameter of a nucleus? Describe the nucleus

10-14m/ made up of nucleons/ protons and neutrons have similar densities - same vol and dense

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What is an isotope?

atoms with the same number of protons and electrons but a different number of neutrons

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Describe the characteristics of isotopes of elements

affect the stability of a nucleus/ unstable nuclei may be radioactive

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Name the forces present within a nucleus

electrostatic/ gravitational and strong nuclear

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Describe the electrostatic forces in a nucleus

all protons have equal positive charge, packed closely will repel/ neutral between neutrons/ long range/ bigger than gravitational

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Describe the gravitational forces in a nucleus

effective is very small/ newton says that two massive objects will attract each other/ attractive/ long ranged/ inverse square law/ use gravitational theory equation

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Describe the strong nuclear force

binds nucleons together/ attractive force greater than electrostatic/ only attractive over short range then become increasingly repulsive (other wise it would collapse)

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What causes a nucleus to decay?

too many neutrons/ too few neutrons/ too many nucleons (too heavy)/ too much energy

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Describe alpha decay

heavy nuclei/ one helium nuclei emitted/ nucleon n decreases by 4 and proton decreases by 2/ only with protons numbers bigger than 82, too big to be stable

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Describe the two types of beta emission

beta minus when lots of electrons/ beta plus when lots of protons

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describe beta minus decay

electron is beta particle/ also relates antineutrino/ one neutron turns into a proton and an electron + anti neutrino/ proton number INCREASES BY 1

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describe beta plus decay

beta particle is positron and neutrino/ proton turns into these/ PROTON N DECREASES BY 1

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Describe gamma ray emission

nuclei with too much energy/ no change in nucleons, just loses energy

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What quantities are conserved in nuclear decay?

charge/ total n of protons and neutrons/ energy/ momentum of system/ lepton number

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What quantities are not conserved in nuclear decay?

mass/ mass of nucleus is less than its constituents - mass defect/ e=mc2 mass and energy are equivalent/ energy released when the nucleons bonds together accounts for missing mass

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Describe the mass defect

e=mc2/ energy released = mass defect x c2// was of system increases when external energy is supplied/ ENERGY IS RELEASED FROM SYSTEM IS MASS INCREASES

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Describe how the strong nuclear force between nucleons is attractive and short ranged

protons do not move apart even though electrostatic force is much greater than gravitational/ must be short ranged attractive force

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5.3.1 THE NUCLEAR ATOM

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