Flashcards in Particles and Radiation Deck (27)
Define the A-Z nuclide notation
A = nucleon number (sum of p + n)
Z = atomic (proton) number
State the charge and mass of a proton.
Charge = 1.60e-19
Mass = 1.67e-27
How do you calculate the specific charge and what is its unit?
- specific charge = charge/mass
- unit = Ckg^-1
Note : charge = Z x 1.60e-19
mass = A x 1.67e-27
How many electrons are there in a neutral atom?
The number of electrons = the number of protons.
State the charge and mass of a neutron
Charge = o
Mass = 1.67e-27
State the charge and mass of an electron.
Charge = -1.60e-19
Mass = 9.11e-31
What is an isotope?
A version of an atom with the same number of protons but different numbers of neutrons.
What characteristic of the atom does changing the number of neutrons affect?
The stability of the nucleus.
What is ionisation?
The removal (or addition) of electrons from (to) an atom or molecule.
How is isotopic data used?
Used to find the percentage of radioactive carbon-14 left in an object (organic matter).
So the approximate age can be calculated.
What is the attractive force responsible for holding the nucleus together?
The strong nuclear force.
What is the range of the strong nuclear force?
• 0.5-3.0 femtometres
• works equally between all nucleons
• at separations smaller than 0.5fm, the force is repulsive so nucleus doesn't crush to a point
• falls rapidly towards zero after 3fm.
What kind of nuclei is alpha decay likely to happen and how does the nucleon and atomic numbers change?
- very large nuclei
- nucleon number decreases by 4
- atomic number decreases by 2
Why is the neutrino present in beta minus decays?
- Hypothesised as a neutral, almost zero mass
- carries away some energy and momentum (conservation of energy)
What happens to the nucleon and proton number in beta minus decay?
- the nucleon number stays the same
- the proton number increases by 1
- a beta minus particle and antineutrino are also emitted
When does gamma radiation take place?
- gamma radiation is electromagnetic radiation emitted by an unstable nucleus
- it is emitted by a nucleus with too much energy, following alpha or beta emission
What end of electromagnetic radiation has the greatest frequency and wavelength?
- highest wavelength = rich men (radio waves -> microwaves)
- frequency = gambling (gamma rays)
What do electromagnetic radiation exist as?
Photons of energy = hf
h = 6.63e-34
f = c/lambda
What do electromagnetic waves consist of?
- an electric wave and a magnetic wave which
• vibrate perpendicular to each other and the direction they're travelling
• travel in phase with each other.
What similarities do particles and it's corresponding antiparticles share? (Name one difference)
- same mass
- same rest energy
- opposite charge
What happens in annihilation?
- a particle and its corresponding antiparticle collide and their mass is converted into radiation energy
- two gamma ray photons
- Emin = hfmin
What happens in pair production?
- a photon creates a particle and a corresponding antiparticle and vanishes in the process
- Emin = 2rest energy
State the electron capture equation.
p + e- -> n + v
State the 3 fundamental forces, their gauge bosons and the particles affected.
1. Electromagnetic, virtual photon, charged particles only
2. Weak nuclear force, W+ or W- boson, all types
3. Strong nuclear force, pions, hadrons only
State the beta plus and beta minus equations
beta minus = n -> p + e- + antineutrino
beta plus = p-> n + e+ + neutrino
What is the role of exchange particles?
Exchange particles transfer