1.2 Stable and unstable nuclei
- Created by: maddie
- Created on: 29-11-12 09:03
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- Stable and unstable nuclei
- Stable nucei don't disintergrate so must be force holding them together -strong nuclear force overc oming electrostatic force of replusion between protons
- Range about 3-4 fm (10^-15).
- atractive from from 4 - 0.5 fm then a repulsive force acting to prevent protons and neutrons being pushed together
- Alpha radiation
- alpha particle - two protons and two neutrons
- proton number 2, mass number 4
- Beta radiation
- beta particle - fast moving electron
- Negative charge, mass number 0
- Gamma radiation
- electromagnetic radiation emmited by unstable nucleus
- Mass 0, charge 0
- emitted by nucleus with too much energy after beta or alpha emission
- can pass through metal
- Neutron in nucleus of unstable atom turns into proton
- beta particle produced and instantly emitted
- antipartcle with no charge, antineutrino emitted
- neutron -> proton, mass number stays same, proton number: +1
- antipartcle with no charge, antineutrino emitted
- happens to nuclei with too many neutrons
- beta particle produced and instantly emitted
- when energy spectrum of beta particle first measured found they were released with kinetic energies up to max depending on isotope
- Scientists puzzled - why energy of beta particle varuied to max when each unstable nuclei lost certain amount of energy in process.
- Either energy not conerved or some take away in mysterious particles - neutrinos or antineutrinos
- 20 years later antineutrino detected
- Either energy not conerved or some take away in mysterious particles - neutrinos or antineutrinos
- Scientists puzzled - why energy of beta particle varuied to max when each unstable nuclei lost certain amount of energy in process.
- Stable nucei don't disintergrate so must be force holding them together -strong nuclear force overc oming electrostatic force of replusion between protons
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