1.2 Particles - Stable and Unstable Nuclei Flashcards
Strong force:
Strong nuclear force or strong interaction acts inside the nucleus between all nucleons and holds it together
Why is there a strong force?
The only charged particles in the nucleus are positive which means the electrostatic repulsion between the protons is very large
Size of nucleus impact on strong force:
As the nucleus is larger, the strong force can only act over a limited distance which results in the nucleus being unstable
Key points on a strong force graph:
Line meets x-axis at 0.5 and 3
Sudden decline until 1 where it curves towards 3 and continues on there
Electrostatic force is a downward exponential slope as always will be some repulsion between same charged particles
Radioisotopes:
isotopes which emit ionising radiation
Radiation of radioisotopes:
Their nuclei are unstable so they are likely to decay to a lower energy state by alpha radiation
Alpha radiation:
Tends to occur in large, unstable nuclei
A stable group of 2 neutrons and 2 protons (helium atom) forms in nucleus and is ejected at high speed
When an alpha particle moves through a medium it has interactions such as losing energy and ionising particles until it collects two free electrons to form a helium atom
Alpha particle properties:
In a cloud chamber or bubble chamber, tracks of alpha particles of a radioisotope are:
All the same length - due to the mono energetic decay
Straight - ionisation takes place between alpha particles and electrons and because alpha particles are bigger they are barely deflected in interactions
General equation for alpha decay:
A -> A -4 ; Z -> Z-2 ; + He
Beta-minus radiation:
Tends to occur in nuclei with an excess of neutrons
Neutrons turns into a proton, electron and electron neutrino
Electron and electron neutrino emitted at high speeds
Graph of beta particle energy and number of particles:
Curvy n shape
General formula for beta-minus decay:
z -> z+1 ; + 0-1e ; + 00Ve^-
