Chapter 1 - Matter and Radiation Flashcards
What is a nucleon?
A neutron or proton in the nucleus
What is the atomic number?
Number of protons in the nucleus
What is an isotope?
Atoms of the same element with the same number of protons but different numbers of neutrons
What is the nucleon number?
The number of neutrons and protons in the nucleus
What is the relative charge of a proton?
+1
What is the relative charge of an electron?
-1
Equation for specific charge
Specific charge = charge ÷ mass
What is the strong nuclear force?
The force that keeps neutrons and protons together in the nucleus
What is the range of the strong nuclear force?
It is attractive from 4 fm to 0.5 fm, and then is repulsive
What is specific charge?
Definition = charge ÷ mass
Electrons have the highest specific charge of any particle (given in equations booklet)
An atom has no charge
What is an alpha particle?
Helium particle / 2 neutrons and 2 protons
What is a beta - particle?
An electron
What is a beta + particle?
A positron
Beta - decay
- Neutron changes into a proton
- An electron and anti electron neutrino are created and emitted
Why is the specific charge of an electron larger then that of a hydrogen nucleus?
The specific charge of an electron is about 2000 x higher because it’s mass is so much smaller. The hydrogen nucleus and an electron have the same charge, but hydrogen’s mass is about 2000 times bigger.
Beta + decay
- A proton changes into a neutron
- A position and an electron neutrino are created and emitted
Neutrino
The neutrino’s existence was predicted because energy was not conserved in beta decay
1 eV
1.6 x 10 to the power of -19 J (in the booklet)
What is a photon?
- A packet of electromagnetic radiation
- The “smallest piece”
- Zero mass
- Zero charge
- Their energy is proportional to their frequency
Equation for energy of a photon
E=hf
Plank’s constant x frequency
Wavespeed
Frequency x wavelength
What is antimatter?
- Every particle has an equivalent antiparticle
- an antiparticle is like the mirror image of the respective particle
Antimatter has opposite charge and the same mass as the matter equivalent
What are the antiparticles?
Proton (p) | antiproton (p_)
Neutron (n) | antineutron (n_)
Electron (e) | positron (e+)
Electron neutrino (Ve) | anti electron neutrino (Ve_)
Beta decay equations
Beta - = n -> p + e + Ve_
Beta + = p -> n + (e+) + Ve
What is annihilation?
- Matter and antimatter destroy each other, or annihilate, whenever they come into contact
- Matter then turns into energy -> E = m x c2
- The matter and antimatter then mutually destructs in a “puff” of light consisting of two photons sent out in precisely opposite directions, each with an energy corresponding exactly to the mass of the matter
- 2 photons are produced in opposite directions to conserve momentum
What is the rest mass?
The rest energy, which is the energy needed to create the particle
What is pair production?
- The opposite of annihilation
- Photons producing a particle and its corresponding antiparticle
- Usually happens in the presence of a nucleus to conserve momentum
- Usually an electron and position as they are the lowest mass
Look on good notes for diagram
Particle interactions
Particle interactions (forces) are caused by exchange particles (bosons, sometimes called message particles)
What are the 4 fundamental particle interactions?
Gravity
Electromagnetic
Weak nuclear
Strong nuclear
How do matter particles interact?
An exchange particle is exchanged between the particles
They are called virtual photons as they only exist for very short periods of time
What is the exchange particle for electromagnetic interaction?
Virtual photon
Weak nuclear force
Responsible for subatomic particle decays like beta - and +
The exchange particles are w- and w+
What is rest energy?
The energy equivalence of the particles mass
