1.2 Stable and Unstable Nuclei Flashcards
What is the β- particle also known as?
An electron
How do the nucleon and proton numbers of an atom change in alpha decay?
Nucleon number decreases by 4.
Proton number decreases by 2.
Give 2 ways of demonstrating the range of alpha particles.
1) Looking at the tracks left by alpha particles in a cloud chamber.
2) Using a Geiger counter to measure the amount of ionising radiation at different distances from an alpha source.
Why does a nucleus undergo nuclear decay?
Because of the forces in the nucleus only have a range of a few femtometres, so they struggle to hold large nuclei together. This makes the nucleus unstable.
What particles are emitted during beta-minus decay?
An electron and an antineutrino.
What type of nuclei will decay by beta-minus decay?
Isotopes which are neutron-rich (i.e have too many neutrons compared to protons in their nucleus).
Describe the changes in the nucleus of an atom when it undergoes beta-minus decay.
A neutron turns into a proton, so the nucleon number stays the same but the proton number increases by one.
Explain how the neutrino was hypothesised as a result of beta decay.
It appeared as though energy was being lost in beta decay. A new particle was hypothesised in order for energy to remain conserved. This particle had to be neutral and was named the ‘neutrino’.
