1.2 Stable and Unstable Nuclei Flashcards
A stable isotope has nuclei that do not…
…disintegrate so there must be a force holding them together
What is the force that keeps a nuclei from disintegrating
Strong nuclear force
As it overcomes the electrostatic force of repulsion between the protons in the nucleus and keeps the protons and neutrons together
Important things to note about the strong nuclear force:
Range is no more than 3-4 femtometres whereas electrostatic force between 2 charged particles has infinite range
Has the same effect between two protons as it does between two neutrons or a proton and a neutron
It is an attractive force from 3-4 fm down to 0.5 fm. At separations smaller than this, it is a repulsive force that acts to prevent neutrons and protons being pushed into each other
What are the types of radiation
Alpha
Beta
Gamma
What does alpha radiation consist of
Alpha particles which each comprise two protons and two neutrons
What is the symbol of alpha radiation
4
α
2
What happens to an unstable nucleus of an element when it emits an alpha particle
Nucleon number A decreases by 4 and atomic number Z decreases by 2
Equation of alpha radiation
A A-4 4
X –> Y + α
Z Z-2 2
What does beta radiation consist of
Fast moving electrons
What is the symbol for an electron as a beta particle
β- or 0 β -1
Why does beta decay happen
As a result of a neutron in the nucleus changing into a proton
Beta particle is created when the change happens and is emitted instantly.
Antiparticle with no charge is emitted (called an antineutrino
Happens to neuclei with too many neutrons, atomic number increases by 1
Equation for beta radiation
A A 0 _
X –> Y + β + V
Z Z+1 -1
What is gamma radiation
Electromagnetic radiation emitted by an unstable nucleus
Can pass through thick metal plates
Has no mass and no charge, is emitted by a nucleus with too much energy following an alpha or beta emission
When the energy spectrum of beta particles was first measured, what did they find
That the beta particles were released with kinetic energies up to maximum that depended on isotope
What are neutrinos and antineutrinos
Mystery particles that carry some energy away
Was unproven for over 20 years until they were detected
