Particles and radiation Flashcards
State what is meant by nucleon.
A particle that is in the nucleus.
State what is meant by specific charge and its units.
The ratio of somethings charge to its mass (e.g. a nucleus or ion)
units = Ckg^-1
What do you do to work out the specific charge of a nucleus?
(Proton no.) X 1.6 x 10^-19
/ (Mass no.) X 1.67 x 10^-27
What do you do to work out the specific charge of an ion?
First workout its overall charge (e.g. lost 2 electrons = +2e or gained 1 electron = -1e etc etc.) Overall charge (x 1.6 x 10^-19) / (Mass no.) X 1.67 x 10^-27
What is the charge of a proton or an electron?
Proton = +1e = 1.60 x 10^-19 Electron = -1e = -1.60 x 10^-19
What is the mass of a proton / neutron and an electron?
Proton / Neutron = 1.67 x 10^-27
Electron = 9.11 x 10^-31
State what is meant by isotope.
An atom with the same number of protons but a different number of neutrons.
State what is meant by ion.
An atom which has lost or gained electrons
It has an overall charge.
When is the strong force repulsive and when is it attractive?
0>0.5fm = repulsive 0.5>3-5fm = attractive
Why does the strong force have to be repulsive at short ranges?
So the protons don’t get pushed together.
What does it mean if something has went through alpha decay?
It will have emitted an alpha particle
Meaning it has lost 2 protons and 2 neutrons
238 U –> 234 Th + 4 α
92 90 2
If beta minus decay takes place in an atom what does this tell you about the nucleus?
It has a neutron rich nuclei.
What happens during beta minus decay using an example?
A neutron turns into a proton emitting an electron (B- particle) and an anti-electron neutrino
n -> p + ß- + ̅νe
If beta plus decay takes place in an atom what does this tell you about the nucleus?
It has proton rich nuclei.
What happens during beta plus decay using an example?
A proton turns into a neutron releasing a positron (anti-electron) and an electron neutrino.
p -> n + β+ + νe
Why was the neutrino predicted?
The beta particles were emitted with a range of different energies from the same isotope.
This did not allow the conservation of energy/mass.
Therefore another particle was predicted to make this decay possible.
What does an antiparticle have?
the same mass as its particle.
Equal but opposite charge.
The same lifetime.
What are photons?
Packets of energy that are mass-less and neutral.
What is the equation for energy including planck’s constant and the speed of light in a vacuum?
E = hc/λ
Planck’s constant x v of light in vacuum
/ wavelength
What does 1 electron volt = in joules?
1eV = 1.60 x 10^-19J
What happens during annihilation?
A particle meets its anti-particle and they annihilate.
The mass of the particle and anti-particle is converted into energy in the form of 2 identical photons.
Why are 2 photons give off during annihilation instead of 1?
2 photons are needed for momentum to be conserved.
What happens during pair production?
A high energy photon vanishes creating a particle and its anti-particle (e.g. electron and positron) -> this conserves charge
Only occurs if the photon has enough energy to produce the total rest mass of the 2 particles.
What is a fundamental particle?
A particle that cannot be broken down any further.
