3.2.1 Particles Flashcards
What are atoms made of ? (The simple model of the atom)
Atoms of elements are made up of three types of particles: Protons, Neutrons, and Electrons
What is the charge of a proton?
1.6x10^-19C (or As)
What is the Mass of a Proton?
1.67x10^-27Kg
What is the charge of a Neutron?
0C (or As)
What is the Mass of a Neutron?
1.67x10^-27Kg
What is the Charge of an Electron?
-1.6x10^-19C (or As)
What is the Mass of an Electron?
9.11x10^-31Kg
What is specific charge?
Charge per Kilogram
How do you calculate the specific charge of a nucleus?
Total charge of protons/ total mass of No. Nucleons
How do you calculate the specific charge of an Ion?
(Total No. electrons added or taken away x 1.6x10^-19)/ total mass of Nucleons
What is an Isotope?
An atom (of the same element) that has an equal number of protons but a different number of neutrons
What is Isotopic data?
The relative amounts of different isotopes of an element found within a substance
What can isotopic data be used for?
To determine the age of substances, using radioactive dating
What is an example isotope used for radioactive dating?
Carbon - 14
Why is there an electrostatic repulsion between nucleons in a nucleus ?
Because of the charge of the protons
What does the strong nuclear force do?
It holds the nucleus together
How does the strong nuclear force hold the nucleus together?
The strong nuclear force holds quarks together, therefore holding the neutrons and protons together
Where is the strong force attractive up to?
3fm (3x10^-15m)
Where is the strong force repulsive up to?
0.5fm (0.5x10^-15m)
Where does the strong force have no effect?
3fm (3x10^-15m)
What is the maximum attractive value of the strong force?
Around 1fm (1x10^-15m)
When does alpha decay occur?
When the nucleus is proton heavy and unstable
What does an alpha particle consist of?
2 protons and 2 neutrons, like a helium atom
What happens to the proton number of an element after alpha decay?
It decreases by 2
What happens to the nucleon number of an element after alpha decay?
It decreases by 4
When does beta-minus decay occur?
With a neutron heavy nucleus
What happens during Beta-minus decay?
A neutron turns into a proton, a high energy electron is emitted along with an anti-neutrino
What happens to the proton number of an element after beta-minus decay
It increases by 1
What is the equation of beta-minus decay?
n –> p + e- + (anti)Ve
When does beta-plus decay occur?
In a proton heavy nucleus
What happens during Beta-plus decay?
A proton turns into a neutron, a high energy positron and an electron neutrino are emitted
What happens to the proton number of the element after the beta-plus decay?
It decreases by 1
What is the equation for beta-plus decay?
p –> n + e+ + Ve
Why was the existence of the neutrino hypothesised?
To account for the conservation of energy in beta decay
For every particle there is a….
Corresponding antiparticle
Antiparticles and particles have the same…. (2)
Mass and Rest-mass energy
Antiparticles and particles are different because they have….
Opposite charge
What is rest energy?
The energy equivalent to the mass of the particle at rest
What is rest energy measured in?
Mega electron volts (MeV)
What is the corresponding antiparticle to a Proton?
An antiproton
What is the corresponding antiparticle to an electron?
A positron
What is the corresponding antiparticle to a Neutron?
An antineutron
What is the corresponding antiparticle to an electron neutrino?
An antielectron neutrino
What is a Photon?
EM radiation travelling in packets
What do photons do?
Transfer energy
What is the equation used to calculate the energy of a photon?
E = hf
What is 1eV equal to in Joules?
1.6x10^-19 J
What relationship does E = hf state?
The energy of the photon is directly proportional to the frequency of the EM radiation
What is Planck’s constant, h?
6.63x10^-34 Js
What happens in annihilation?
An antiparticle, particle pair are destroyed and their masses are converted to energy to form gamma ray photons
Why are the gamma ray photons emitted in opposite directions?
To conserve momentum
What is the minimum energy of one photon after annihilation?
E (min) = hf (min)
What is pair production?
When a photon is converted into an equal amount of matter and antimatter
When does pair production occur? (2)
When the photon has an energy greater than the total rest energy of both particles
When a photon collides with a nucleus
What happens to excess energy in pair production?
It’s converted into the kinetic energy of the particles
What is the minimum energy for a photon to undergo pair production?
E (min) = hf (min) = 2E
What are the four fundamental forces? (4)
The strong nuclear force
The weak nuclear force
Gravity
Electromagnetic force
What is the weakest fundamental force?
Gravity
Which fundamental forces have an infinite range? (2)
Electromagnetic and Gravity
What is the range of the Weak nuclear force?
Up to 10^-18 m
What is the range of the Strong nuclear force?
10^-15 m
Which force is stronger, the Electromagnetic or the Weak nuclear force?
Electromagnetic
Which fundamental force only affects particles with mass?
Gravity
Which fundamental force only affects particles with charge?
Electromagnetic
Which fundamental force affects all particles?
Weak nuclear force
Which Which fundamental force only affects hadrons?
Strong nuclear force
What is the argument for exchange particles?
There cannot be instantaneous action at a distance when two particles interact
When two particles exert a force on one another …..
…… a virtual particle is created
What do exchange particles do?
Carry the fundamental force between each particle
What is the exchange particle for the Electromagnetic force?
A virtual photon
What are the exchange particles for the Weak nuclear force? (3)
W+ boson , W- boson , Z° boson
What is the exchange particle for the Strong nuclear force between nucleons?
Pions
What is the exchange particle for the Strong nuclear force between quarks?
gluons
What are examples of the weak interaction? (4)
β+ decay , β- decay, electron capture and electron - proton collision
What is the equation for β+ decay? and what is the exchange particle (left to right)?
p —-> n + e+ + Ve , W+ boson
What is the equation for β- decay? and what is the exchange particle (left to right)?
n —-> p + e- + Ve (anti) , W- boson
What is the equation for electron - proton collision? and what is the exchange particle (left to right)?
p + e- —-> n + Ve , W+ boson
Which is the only fundamental force that hadrons are subject to?
The strong interaction
What are the two classes of hadron? (2)
Baryons and mesons
What are the two types of Baryons? (2)
Protons and neutrons
What are the two types of mesons? (2)
Kaons and Pions
Baryon number is a ….. number
Quantum
What is a quantum number? (2)
A number which is always conserved and a whole number
What is the quark structure of a baryon?
qqq
What is the quark structure of a meson?
q (anti)q
Which baryon is the only stable baryon, which all other baryons will eventually decay into?
Proton
What particles do kaons eventually decay into?
Pions
What are the three types of Lepton? (3)
Electrons
Muons
Neutrinos
Leptons are ….. particles
fundamental
Which fundamental force do leptons not feel?
The strong interaction
Lepton number is a ….. number
Quantum
Lepton number is always conserved as which two numbers? (2)
Muon lepton number
Electron lepton number
Muons eventually decay into what?
Electrons
What two properties make muons different to electrons? (2)
They are much heavier and unstable
Which interaction is strangeness produced by?
Strong
Strangeness is a …. number
Quantum
Strange particles decay via which interaction?
Weak
Why are strange particles always produced in pairs?
To conserve strangeness
Which interaction is strangeness conserved?
Strong
When strange particles decay strangeness can decay by …..
0 , +1 , -1
Particle physics relies on the ….. efforts of a range of teams of ….. and …. to validate new ……
Collaborative, Scientists and engineers, Knowledge
What is the strangeness of Positive and neutral kaons?
+1
What is the quark structure of a neutral pion? (2)
u (anti)u , d (anti)d
What is the strangeness of a negative kaon?
-1
What is the quark structure of a positive kaon?
u (anti)s
What is the quark structure of a negative kaon?
(anti)u s
What is the change in quark structure during beta minus decay?
d —> u
What is the change in quark structure during beta plus decay?
u —> d
Which six properties are always conserved in particle interactions? (6)
Energy
Momentum
Charge
Baryon number
Electron Lepton number
Muon Lepton number
