Nuclear Physics Flashcards
Strong nuclear force vs weak nuclear force vs electric force vs binding energy vs mass defect
Attractive force b/w p+ and n0 —> holds nucleus together –> stable nucleus vs sometimes nucleus falls apart => decay –> unstable nucleus vs repulsive force b/w pos charged p+ vs energy that allows nucleons to bind together in nucleus; peaks at iron —> iron has most stable nucleus; E = mc^2, always has pos value b/c breaking a nucleus = endothermic vs mass of whole nucleus is actually smaller than sum of individual nucleons’ masses; this mass is used to find binding energy (ie. This mass is “m” in mc^2) b/c when you lose mass, you release energy
What happens in alpha decay?
4_2He; lose 2 p+ and 2 n0; -4 in mass # and -2 in atomic #
What is transmutation?
when daughter nucleus = diff than parent nucleus (as it does in ALL radioactive decay)
Why does alpha decay occur?
b/c strong nuclear force isn’t strong enough to hold nucleus together. That’s why electric force in large nuclei outweighs strong force and decays easier. This decay emits an alpha particle. ALSO ALPHA DECAY OCCURS B/C TOO MANY P+
Nucleus emits what in alpha vs beta- vs beta+ vs gamma decay
alpha particle (4_2He) vs e-/beta- particle + antineutrino vs e+/beta+ particle + neutrino vs photon, no change in element
What happens in beta- vs beta+ decay? What’s the preference?
Z + 1, emits e- and antineutrino vs Z - 1, emits e+ aka positron and neutrino
when too many n0 vs when too many p+
Are nucleus e- the same as orbital e- in beta decay?
nope
What’s e- capture?
Essentially the opposite of beta decay; when nucleus absorbs an orbiting e- –> Z-1 + neutrino (same formula like beta+ decay)
What happens in beta- vs beta+ decay in terms of neutrons?
beta-: n0 turns into p+ —> beta- particle vs beta+: p+ turns into n0 —> beta+ particle
When does gamma ray occur?
when nucleus jumps down to a lower energy state, it emits a photon => gamma ray
Know half life vs mean life formula
T1/2 = 0.693/lambda vs tau = 1/lambda
Know decay rate (aka activity) formula. What are the units?
deltaN/deltat = -lambda*N R = abs(deltaN/deltat) = Roe^-lambda*t decay/s = 1 Bacquerel (Bq)
Know exponential decay formula
N = Noe^-lambda*t
Is bonding energy pos or neg? Does it take energy to break a bond or make a bond?
bonding energy = neg –> releases energy. It takes energy to break a bond
The larger the bombarding particle and the greater its charge, the more difficult it is to use in artificial transmutation. What’s the order of particles in terms of increasing ability given that charge is the most important factor?
Alpha particles < p < e < n
Max and min kinetic energy of e-
K = hf-W
K=max energy to eject e-
W=min energy to eject e-; W (aka work function) = hf_T where f_T = min freq to eject e-, an all or nothing response
Photoelectric effect
When a photon hits an e- on a metal surface in a vacuum, the photon = absorbed and that e- gets kicked off the surface. The liberated e- will produce a current
Energy of ejected e- depends on freq, not intensity. Stronger intensity of photons —> MORE e- kicked out (all the ejected e- just have the same KE)—> stronger current
It takes all or none energy, no portions
Showed that light acts both as waves and particles
How to find energy of a photon/light quantum
Planck’s eqn: E = hf
h = 6.626E-34 J*s
1 Angstroms in meters
10^-10 m
What causes fluorescence?
Stepwise photon emission from e- moving from excited state to ground state
If there are small changes in chemical structure, will there be small changes in absorption spectrum?
Nope, it’ll be a big change
Fusion vs fission
Small nuclei combining to make a bigger nucleus vs a big nucleus splitting into smaller nuclei
Mass number vs atomic number symbols
A vs Z
What are the 4 fundamental forces of nature?
Strong and weak nuclear forces, electrostatic forces and gravity
How do you know if a fusion or fission of an element will require energy?
Iron has most stable nucleus. If the element is going towards Fe —> no energy required; if the element is going away from Fe —> energy required
What has bigger mass: alpha particle or beta particle?
alpha > beta; that’s why alpha can’t penetrate as far as beta can; alpha decay particles have higher ionizing power and low penetration b/c they’re too big, gamma decay particles have high penetration b/c they’re tiny
Which type of radiation/decay is most energetic?
gamma radiation
