M6, C4 Nuclear and Particle Physics Flashcards
atomic structure the nucleus particles and antiparticles quarks and antiquarks radioactive decay nuclear decay equations exponential law of decay half-life and radioactive dating binding energy nuclear fission and fusion fission reactors
what are the relative charges of:
- proton
- antiproton
- neutron
- antineutron
- electron
- positron
- neutrino
- antineutrino
- proton: +1
- antiproton: -1
- neutron: 0
- antineutron: 0
- electron: -1
- positron: +1
- neutrino: 0
- antineutrino: 0
what are antiparticles
each particle type has a corresponding antiparticle with the same mass but the opposite charge
what is a neutrino
symbol is v
mass and relative charge are 0
lepton
only take part in weak interactions
what is the symbol for an antiproton
_
p
whats the symbol for a positron
e+
what are hadrons
give examples
they are made up of quarks
eg. protons and neutrons
what does a neutron decay into
a proton, an electron and an antineutrino
what are leptons
give examples
they are fundamental particles (can’t be split into smaller particles)
eg. electrons and neutrinos
what’s the antiparticle of an electron
positron
what are quarks
they are the building blocks for hadrons like protons and neutrons
there are 6 flavours
what is the symbol and charge of the 3 anti-quarks, anti-up, anti-down and anti-strange?
anti-up: u with a line on top and a charge of -2/3e
anti-down: d with a line on top and a charge of +1/3e
anti-strange: s with a line on top and a charge of +1/3e
what quarks are protons made of
2 up quarks and 1 down quark because
2/3 + 2/3 -1/3 = +1
what quarks are neutrons made of
1 up quark and 2 down quarks
2/3 + -1/3 + - 1/3
= 2/3 - 1/3 - 1/3 = 0
what are mesons
made of one quark and one anti-quark
what is the conservation of charge
in any particle reaction, the total charge after the reaction must equal the total charge before the reaction
identify the missing quark and name the particle
uus -> ?dd + u(d with a line on top)
uus = 2/3 +2/3 - 1/3 = +1
?dd = ? - 1/3 -1/3 = ?-2/3
ud with a line on top = 2/3 + 1/3 = +1
+1 = ?-2/3 +1
? = +2/3
this is an up quark
the particle is therefore ‘udd’ which is a neutron
what is einstein’s mass-energy equation and what does it mean
∆E = ∆mc^2
energy can turn into mass and mass can turn into energy
The mass of a proton at rest is 1.673 X 10^-27 kg.
Calculate the energy that would be released if this proton were completely converted into energy.
∆E = ∆mc^2
=1.673 X10^-27 X (3 X 10^8)^2
= 1.51 X 10^-10 J
what nuclear forces are hadrons subject to?
what nuclear forces are leptons subject to?
all hadrons are subject to both the strong nuclear force and the weak nuclear force
all leptons are subject to the weak nuclear force but not the strong nuclear force
what was the Rutherford alpha-scattering experiment
a stream of alpha particles from a radioactive source was fired at a thin gold foil
flashes of light were produced and Geiger and Marsden counted these flashes
most alpha particles went straight through but a few scattered at angles greaters than 90 degrees
what conclusions did Rutherford conclude from the alpha scattering experiment with the alpha particles being sent through a thin gold foil
- most of the alpha particles went straight through the foil so the atom is mainly empty space
- some alpha particles were deflected through large angles so the centre of the atom must have a highly positive charge to repel them
- very few particles were deflected by angles greater than 90 degrees so the nucleus must be tiny
- most of the mass must be in the nucleus since the fast alpha particles were deflected backwards by the nucleus
what is the actual charge of a proton
+1.6 X 10 ^-19 C
what is the diameter of an atom
0.1 nm
what is the diameter of a nucleus
a few femtometres
1 fm = 1 X 10^-15 m