Particles Flashcards
what are the 3 constituents that makes up an atom
protons neutron and electrons
what is found at the center of an atom and what is it made up of
a nucleus and is made up of protons and neutrons
what are protons and neutrons also known as
nucleons
where are electrons found in an atom
they are found in shells orbiting the nucleus
what is the charge of a proton neutron and electron
proton - +1.6x10^-19
electron - -1.6x10^-19
neutron - 0
what is the relative charge of a proton neutron and electron
proton - +1
electron - -1
neutron - 0
what is the mass of a proton neutron and electron
proton and neutron - 1.67x10^-27
electron - 9.11x10^-31
what is the relative mass of a proton neutron and electron
proton and neutron - 1
electron - 0.0005
what is the specific charge of a proton neutron and electron
proton - 9.58x10^7
neutron - 0
electron - 1.76x10^11
what are the units for specific charge
CKg^-1
what is the specific charge of a particle and how do you calculate it
the charge-mass ratio and is calculated by dividing a particles charge by its mass
what is an isotope
are atoms with the same number of protons but different numbers of neutrons
what is an example of an isotope
carbon-14 is a radioactive isotope of carbon which can be used to find the approximate age of an object containing organic material. this is done through carbon dating, which involves calculating the percentage of carbon-14 remaining in the object, and using the known starting value of carbon-14 and its half life to calculate an approximate age
how does the strong nuclear force keep the nuclei stable
by counteracting the electrostatic force of repulsion between protons in the nucleus(as they have the same charge). it only acts on nucleons and has a very short range, where it is attractive up to separations of 3 fm, but repulsion below separations of 0.5 fm,
what causes an unstable nuclei
when an atom has too many of either protons, neutrons or both causing the SNF to not be enough to keep them stable, therefore these nuclei will decay in order to become stable. the type of decay the nuclei will experience depends on the amount of each nucleon in them
where does alpha decay occur
in a large nuclei, with too many of both protons and neutrons
in the equation for alpha decay what happens to the proton number and nucleon number
the proton number decreases by 2
the nucleon number decreases by 4
where does beta minus decay occur
in nuclei which are neutron-rich (have too many neutrons)
what happens the the proton number and nucleon number in the equation for beta minus decay
the proton number increases by 1
the nucleon number stays the same
how did scientists theorize that there is a neutrino in beta minus decay
at first, scientists believed that only an electron was emitted from the nucleus during beta minus decay, however observations of the energy levels of the particles before and after the decay showed that energy was not conserved. this does not follow the principle of conservation of energy, and therefore neutrinos were hypothesized to account fir this, and later they were observed
what is there for every type of particle
an antiparticle
what do antiparticles have the same as the particle
the same rest energy and mass but all other properties are opposite
what is the antiparticle of an electron and neutrino
positron and antineutrino
what do electromagnetic radiation travel in
packets called photons which transfer energy and have no mass
what is the energy of photons directly proportional to
the frequency of electromagnetic radiation
what equation shows that the energy of photons is directly proportional to the electromagnetic radiation
E = hf = (hc/lambda)
what is the value of plancks constant
6.63x10^-34 Js
what is annihilation
is where a particle and its corresponding antiparticle collide, as a result their masses are converted into energy
what is the energy during annihilation released as
is released in the form of two protons moving in opposite directions in order to conserve momentum
what is an application of annihilation and how does it work
is used in a PET scanner
this allows 3D images of the inside of the body to be taken, therefore making medical diagnoses easier. this is done by introducing a positron-emitting radioisotope into the patient, as positrons are released they annihilate with electrons already in the patients system, emitting gamma photons which can easily be detected
what is pair production
is where a photon is converted into n equal amount of matter and antimatter. this can only occur when the photon has an energy greater than the total rest energy of both particles, any excess energy is converted into kinetic energy of the particles
what are the 4 fundamental forces
gravity
electromagnetic
weak nuclear (WNF)
strong nuclear (SNF)
what are forces between particles caused by
exchange particles
what do exchange particles do
they carry energy and momentum between the particles experiencing the force and each fundamental force has its own exchange particles
if the interaction is strong what is the exchange particle, range and what does it act on
exchange particle - gluon
range - 3x10^-15
acts on - hadrons
if the interaction is weak what is the exchange particle, range and what does it act on
exchange particle - W boson (W+ OR W-)
range - 10^-18
acts on - all particles
if the interaction is electromagnetic what is the exchange particle, range and what does it act on
exchange particle - virtual photon
range - infinite
acts on - charged particles
if the interaction is gravity what is the exchange particle, range and what does it act on
exchange particle - graviton
range - infinite
acts on - particles with mass
what is the nuclear force responsible for
beta decay, electron capture, and electron-proton collisions all of which can be represented as the particle interaction diagrams
what is the equation for electron capture and electron-proton collision
- p + e- –> n + Ve
what is different about electron capture and electron-proton collisions
they have different exchange particles
what is the equation for beta plus decay
p –> n + e+ +Ve
what is the equation for beta minus decay
n –> p + e- + -Ve
what are all particles classified as
either hadrons or leptons
what is the difference between leptons and hadrons
leptons are fundamental particles
what classifies a particles as a fundamental particle
they cannot be broken down any further and they do not experience a strong nuclear force
what are hadrons formed from
quarks
what can hadrons be further separated into
baryons, antibaryons and mesons
what are baryons formed of
3 quarks
what are antibaryons formed of
3 antiquarks
what are mesons formed from
a quark and a antiquark
what does the baryon number show
shows whether it is a baryon (if 1), an antibaryon (if -1), or not a baryon (if 0)
what is the only stable baryon
a proton, therefore all baryons will eventually decay into a proton either directly or indirectly
what does the lepton number show
shows whether it is a lepton (if 1), antilepton (if-1) and not a lepton (if 0)
what are the two types of lepton numbers
electron lepton number
muon lepton number
are baryon numbers and lepton numbers conserved in particle interactions
yes
what is a muon also known as and what does it decay into
a ‘heavy electron’ and decays into an electron
what are strange particles
are particles which are produced by the strong nuclear interaction but decay by the weak interaction
what are the strange particles you need to know about
a kaon which decay into pions through the weak interaction
what is strangeness
is a property of particles which shows that strange particles must be created in pairs, as strangeness must be conserved in strong interactions however in weak interactions strangeness can change by 0,+1,-1
what is needed to investigate particle physics but what are the cons
particle accelerators however they are expensive to build and run and also produce high amounts of data, scientific investigations rely on collaboration of scientists internationally
what are quarks
are fundamental particles which make up hadrons
what are the three types of quarks
up, down, strange
what is the charge baryon number and strangeness of an up quark
charge - +2/3e
baryon number - +1/3
strangeness - 0
what is the charge baryon number and strangeness of a down quark
charge - -1/3e
baryon number - +1/3
strangeness - 0
what is the charge baryon number and strangeness of a strange quark
charge - -1/3e
baryon number - +1/3
strangeness - -1
when quarks combine what do they form
baryons and mesons
how do you find the quark combination of an antibaryon
if you know the quark combination of the baryon is to simply change the quarks into their respective antiquarks. also true for mesons
as all baryons decay into protons what else will decay into a proton
a neutron
what is the equation for neutron or baryon decay
n –> p + e- + -Ve
what properties must always be conserved in particle interactions
-energy and momentum
-charge
-baryon number
-electron lepton number
-muon lepton number
what is conserved in only strong interactions
strangeness
how do you show these conservation laws are obeyed in an interaction
you must find the value of each property before and after the interaction and make sure they are equal
what causes beta minus and beta plus decay
by the weak interaction because there is a change in quark type
in beta minus decay what must happen to the quark in order for a neutron to become a proton
a down quark must change into an up quark
