# Matter and Radiation - Unit 1 AQA Physics

Mindmap covering Chapter 1 - Matter and Radiation, from Nelson Thornes AQA AS Physics

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• Inside the atom
• proton - +1.6x10^-19C... 1.67x10^-27kg
• electron -1.6x10^-19C... 9.11x10^-31kg
• neutron - 0C... 1.67x10^-27kg
• Isotopes = atoms with the same number of protons and different numbers of neutrons
• m/z ratio = specific charge
• Don't forget to multiply the mass and charge by the number of particles involved (atomic number)
• Stable and unstable nuclei
• Strong nuclear force - keeps protons and neutrons together
• attractive until 0.5fm, repulsive from here
• Alpha Decay
• Beta Decay
• Photons
• electromagnetic waves consist of an electric wave and a magnetic wave which travel together and vibrate...
• ...at right angles to each other and to the direction in which they are travelling
• ...in phase with each other
• packet of electromagnetic waves
• E = hf
• Power of the beam = nhf
• n = number of photons in the beam passing a fixed point each second
• f = frequency of photons
• h = plank's constant
• = c/f
• Particles and antiparticles
• particle and antiparticle...
• meet... annihilation
• a particle and corresponding antiparticle meet and their mass is converted into radiation energy
• meet...total rest mass converted to photons
• have exactly the same rest mass
• have exactly opposite charges
• Positron emission = positron changes to neutron in anstable nucleus with too many protons
• pair production - photon with sufficient energy changes to a particle-antiparticle pair, which then separate from each other
• minimum energy of photon needed = 2E..=hf
• 1eV = the energy transferred when an electron is moved through a potential difference of 1V
• Cloud chamber - discovery of the positron
• how particles interact
• EM force - momentum is conserved
• due to the exchange of virtual photons (Feynman)
• Weak nuclear force
• causes a neutron to change to a proton, or a proton to change to a neutron
• W bosons
• have a non-zero rest mass
• have a range of no more than about 0.001fm
• are positively charged or negatively charged
• Beta decay
• W- decays to a B- and an antineutrino
• W+ decays to a B+ and a neutrino
• Electron capture
• proton in a proton rich nucleus turns into a neutron as a result of interacting through the weak interaction
• W+ changes the electron to a neutrino
• the same can happen when a proton and an electron collide at very high speed
• for an electron with sufficient energy, the overall change could occur as a W- exchange from the electron to the proton

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where it says atractive until 0.5fm, its repulsive below 0.5fm, attractive between 0.5 and 3 fm and attraction drops off rapidly after 3fm, just to let you know

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