3.2.1.2 Particles and Radiation: Stable and unstable nuclei Flashcards
What is the strong nuclear force?
A force which overcomes the electrostatic force of repulsion between protons in the nucleus and keeps the protons and neutrons together
What is the range of the strong nuclear force?
3-4 fm, this range is about the same as the diameter of a small nucleus. It is attractive from 3-4 fm, to about 0.5 fm. At separations smaller than this it is repulsive and acts to prevent neutrons and protons being pushed into each other.
What is the effect of the strong nuclear force?
It has the same effect between two protons as it does between two neutron or a proton and a neutron
What are the three types of radiation?
Alpha
Beta
Gamma
Describe alpha radiation
Alpha particles which contain two protons and two neutrons.
Describe beta radiation
Fast moving electrons. It happens as a result of a neutron in a nucleus changing into a proton - the beta particle is created when the change happens and is emitted instantly, an antiparticle with no charge is also emitted (antineutrino). The antineutrino particle carries away some energy and momentum
Describe gamma raditation
Electromagnetic radiation emitted by an unstable nucleus. It can pass through thick metal plates and has no mass or charge. It is emitted by a nucleus with too much energy following an alpha or beta emission.
How were neutrinos and antineutrinos discovered?
When the energy spectrum of beta particles was first measured it was found that the beta particles released with kinetic energies up to a maximum that depended on the isotope. The scientists at the time were puzzled as to why the energy of beta particles varied up to a maximum, when each unstable isotope lost a certain amount of energy in the process. They proposed that the missing energy was carried away by particles called neutrinos and antineutrinos
When does beta radiation usually happen?
In neutron rich nuclei
