Topic 7 - Atomic, nuclear and particle physics Flashcards
What are feynman diagrams used for?
To show particle interactions or transformations.
What are the 4 Fundamental Forces
- Gravitational force
- Electrostatic force
- The Strong Force
- Weak Force
What are the conservation laws?
- charge must be conserved
- baryon number must be conserved
- lepton number must be conserved
What are the 2 fundamental particles?
- Hadrons (affected by the strong force, made of quarks)
- Leptons (not affected by the strong force, not made of quarks)
What is an isotope?
An isotope has the same proton number but different nucleon number than the mother element.
What is an alpha- particle composed of?
Two protons and two neutrons.
Definition: Half Life
The time it takes for half the initial atoms/ nuclei to decay.
The time it takes for the activity of a radioactive sample to decrease by 50%
“The existence of atomic energy levels is supported by…”
evidence from emission and absorption spectra
How are emission and absorption spectra formed?
When electrons in an atom move between energy levels.
5 correct statements about the Strong interaction:
- One of the 4 fundamental forces
- Range: 10^-15 m
- Binds atomic nuclei
- Acts on quarks and gluons
- Mediating particle: gluon
What are photons?
Photons are massless, uncharged particles that carry energy.
They are also emitted during gamma decay.
On the graph that shows how average binding energy per nucleon varies with nucleon number, the most stable elements can be found:
around the maximum point of the graph.
“A positron is emitted together with a …. and an electron is emitted together with an…”
A positron is emitted together with a neutrino and an electron is emitted together with an antineutrino”
(1 anti-particle and 1 regular particle”)
How do you find the number of wavelength’s in the absorption spectrum of an atom?
The number of wavelengths/ lines in the spectrum is equal to the number of different possible energy level transitions.
Types of Lepton (6)
electron (- charge), electron neutrino (0 charge)
muon (-), muon neutrino(0)
tauon(-), tauon neutrino (0)
5 things to know about the Higgs Boson Model:
- It was predicted before it was observed
- It is part of the Standard Model
- It is not a force-mediating particle/gauge boson
- It has a large mass
- It has no charge
What are Mesons composed of ? ( + two examples)
All mesons are composed of 1 quark and 1 anti-quark and have a baryon number of zero
pion π
kaon K
“The Rutherford- Geiger Mardsen Experiment found that… (2 things)”
Almost all of the atom’s mass is concentrated in a very small region of the atom.
This small region is positively charged.
What is the SI unit of radioactivity?
The bequerel (Bq)
How are emission spectrum formed?
When electrons transition from higher to lower energy levels.
What is the relationship between wavelength, frequency and energy
Wavelength is inversely proportional to frequency and energy.
Total binding energy
The total binding energy of a nucleus is the mass defect multiplied by c^2
The total energy needed to separate the nucleons of a given nucleus.
What is mass defect?
The difference between the sum of the individual masses of the isotope’s constituents and the rest mass of the isotope.
What is the ratio of decayed to undecayed nuclides in a radioactive sample after one half-life?
The ratio is 1
What are the respective quark compostitions of a proton and a neutron?
proton: u u d
neutron: u d d
What happens during beta minus decay?
A neutron decays into a proton and a W- boson (carrier) which decays into an electron and an anti electron neutrino
What does the nucleon number (at the top show)?
The total number of protons and neutrons in the nucleus.
The Rutherford-Geiger-Mardsen scattering experiment provided evidence for a new model of the atom.
Describe this model.
The atom has a very small positively charged nucleus that contains almost all the mass of the atom.
Negatively charged electrons orbit the nucleus.
Explain why, based on classical physics, electrons would not orbit the nucleus.
An electron in orbit performs circular motion.
During circular motion, the electron is accelerated.
When an electron is accelerated, it loses energy in the form of electromagnetic radiation.
As a result, the electron would get closer and closer to the nucleus and eventually spiral into the nucleus.
