Definitions Flashcards
(27 cards)
Define the terms proton number and nucleon number
Proton number refers to the number of protons in the nucleus (Z) it defines the element.
The nucleon number is the number of protons and neutrons in the nucleus.
Define isotopes
Atoms with the same number of protons but different number of neutrons.
Define the specific charge of a particle
The specific charge of a particle is the ratio of its charge to its mass, given in C/kg.
Define antiparticles and name the antiparticles of protons, neutrons, electrons and electro-neutrinos
Antiparticles are identical to its particle counterpart but with opposite charge. Hence they have same mass and rest energy.
Protons → Antiproton
Neutron → antineutron
Electron → positron
electron neutrino → anti neutrino
Define leptons
Leptons are fundamental particles (not made up by quarks)
They are not affected by the Strong Nuclear Force, they instead interact via the weak interaction and gravitational and electromagnetic forces.
state the names of the 4 main leptons and their antiparticles
electron, e- → positron
muon, μ- → antimuon (highly unstable)
electron neutrino, ν (e) → electron anti neutrino (only take part in weak interactions)
muon neutrino ν (μ) → muon anti neutrino (only take part in weak interactions)
State the properties of the lepton antiparticles
Opposite charge and lepton numbers when compared to the particle.
State the significance of muons
Define hadrons in terms of the strong nuclear interaction
Hadrons are particles that can feel the strong nuclear force. They are made up from quarks held together by strong interaction.
state the names of the two classes of hadrons
There are two classes of hadrons:
• Baryon (3 quarks or 3 antiquarks) [can’t mix quarks and antiquarks]
• Mesons (quark and antiquark pair)
State the significance of the proton
Most stable baryon and lightest
All baryons decay to protons and protons cannot decay as it would violate the conservation of baryon number
State the significance of the pion and the kaon
Pions and kaons were discovered in cosmic rays and can be observed through a cloud chamber.
Kaons are unstable and decay into pions in a weak interaction. This takes long due to the strange quark which prolongs lifetimes.
The PION (most stable meson) is the exchange particle of the nuclear force. They are responsible for binding nucleons together (strong nuclear force)
State the interaction through which strange particles are produced
Strange particles are produced through the strong interaction
State the interaction through which strange particles decay
Strange particles decay through the weak interaction.
State in which interaction strangeness is always conserved
Strong interactions
State the 5 properties that are conserved in all particle interactions and the other property that is only conserved in the strong interaction
•Charge, Q
•Baryon Number, B
•Lepton Number, L
•Energy
•Momentum
[strangeness if strong interaction]
State or deduce the combination of quarks and antiquarks required for given common baryons or mesons
Baryons are made from three quarks or three antiquarks, proton uud and neutron udd
State the exchange particle for each of the 4 fundamental interactions
these are called gauge bosons
STRONG : pion between nucleons and gluons between quarks
WEAK: W+ (beta plus), W-(beta minus), Z0
ELECTROMAGNETIC: photon
Gravity is negligible
The theorised exchange particle for the gravitational force is the graviton, however, this has not yet been discovered
Define the term ‘photoelectrons’
The electrons emitted from the surface of a metal upon the absorption of electromagnetic radiation.
Define the term ‘threshold frequency’
The minimum frequency of incident electromagnetic radiation required to remove a photoelectron from the surface of a metal
Define the term ‘work function of a metal’
The minimum energy required to release a photoelectron from the surface of a metal
Define ‘stopping potential’ in the photoelectric effect
The potential difference required to stop photoelectron emission from occurring
Define the electron-volt
The energy gained by an electron travelling through a potential difference of one volt
1 eV = 1.6 × 10-19 J [E= Q/V ]
Define the terms ‘excitation’ and ‘ionisation’ in atoms
Excitation refers to the movement of an electron move up energy levels by absorbing protons.
Ionisation refers to when electrons are removed.
