6.4 Nuclear Flashcards
Alpha particle scattering experiment and what it proved
A stream of alpha particles were emitted at a piece of gold foil. Most of the particles went straight through, but some were reflected back. This meant that matter must be mostly empty space with small, dense positively charged pockets (the nucleus)
fm
femtometer - 10-15m
Standard notation for an atom
AZX
Where
A is mass number
Z is proton numbe
Strong nuclear force
The force that holds the nucleus together against the repulsion of the electrostatic repulsion
How the strong force varies with distance
Repulsive < 0.5 fm
Attractive enough to overcome electrostatic repulsion at < 3 fm
Hadron
Particles that feel the strong nuclear force (made of quarks)
What is the only stable hadron
Proton
Lepton
Fundamental particles that don’t feel the strong force but do feel the weak nuclear force
Examples of hadrons (2)
proton, neutron
Examples of leptons (2)
Electron, neutrino
Antiparticle and its properties
Every particle has an antiparticle with the same properties, except it will have the opposite charge
Pair production
When energy is transformed into a particle and an antiparticle
How a gamma ray might create antimatter
A high energy photon can turn into a electron and a positron via pair production. The energy of the photon (hf) is transformed into the mass of the two produced particles (leftover energy is put to their kinetic energy)
Annihilation
When a particle meets its antiparticle the mass of both is converted into energy in the form of two photons
Quark
The building block of hadrons
Quark composition of a proton
uud
Quark composition of a neutron
udd
up quark charge
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