Nuclear Physics

Question 1

Strong nuclear force vs weak nuclear force vs electric force vs binding energy vs mass defect

Answer 1

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

Question 2

What happens in alpha decay?

Answer 2

4_2He; lose 2 p+ and 2 n0; -4 in mass # and -2 in atomic #

Question 3

What is transmutation?

Answer 3

when daughter nucleus = diff than parent nucleus (as it does in ALL radioactive decay)

Question 4

Why does alpha decay occur?

Answer 4

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+

Question 5

Nucleus emits what in alpha vs beta- vs beta+ vs gamma decay

Answer 5

alpha particle (4_2He) vs e-/beta- particle + antineutrino vs e+/beta+ particle + neutrino vs photon, no change in element

Question 6

What happens in beta- vs beta+ decay? What’s the preference?

Answer 6

Z + 1, emits e- and antineutrino vs Z - 1, emits e+ aka positron and neutrino
when too many n0 vs when too many p+

Question 7

Are nucleus e- the same as orbital e- in beta decay?

Answer 7

nope

Question 8

What’s e- capture?

Answer 8

Essentially the opposite of beta decay; when nucleus absorbs an orbiting e- –> Z-1 + neutrino (same formula like beta+ decay)

Question 9

What happens in beta- vs beta+ decay in terms of neutrons?

Answer 9

beta-: n0 turns into p+ —> beta- particle vs beta+: p+ turns into n0 —> beta+ particle

Question 10

When does gamma ray occur?

Answer 10

when nucleus jumps down to a lower energy state, it emits a photon => gamma ray

Question 11

Know half life vs mean life formula

Answer 11

T1/2 = 0.693/lambda vs tau = 1/lambda

Question 12

Know decay rate (aka activity) formula. What are the units?

Answer 12

deltaN/deltat = -lambda*N
R = abs(deltaN/deltat) = Roe^-lambda*t
decay/s = 1 Bacquerel (Bq)

Question 13

Know exponential decay formula

Answer 13

N = Noe^-lambda*t

Question 14

Is bonding energy pos or neg? Does it take energy to break a bond or make a bond?

Answer 14

bonding energy = neg –> releases energy. It takes energy to break a bond

Question 15

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?

Answer 15

Alpha particles < p < e < n

Question 16

Max and min kinetic energy of e-

Answer 16

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

Question 17

Photoelectric effect

Answer 17

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

Question 18

How to find energy of a photon/light quantum

Answer 18

Planck’s eqn: E = hf

h = 6.626E-34 J*s

Question 19

1 Angstroms in meters

Answer 19

10^-10 m

Question 20

What causes fluorescence?

Answer 20

Stepwise photon emission from e- moving from excited state to ground state

Question 21

If there are small changes in chemical structure, will there be small changes in absorption spectrum?

Answer 21

Nope, it’ll be a big change

Question 22

Fusion vs fission

Answer 22

Small nuclei combining to make a bigger nucleus vs a big nucleus splitting into smaller nuclei

Question 23

Mass number vs atomic number symbols

Answer 23

A vs Z

Question 24

What are the 4 fundamental forces of nature?

Answer 24

Strong and weak nuclear forces, electrostatic forces and gravity

Question 25

How do you know if a fusion or fission of an element will require energy?

Answer 25

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

Question 26

What has bigger mass: alpha particle or beta particle?

Answer 26

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

Question 27

Which type of radiation/decay is most energetic?

Answer 27

gamma radiation