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Physics 30 > Nuclear Physics > Flashcards

Nuclear Physics Flashcards

1
Q

What does the atomic number tell you?

A

The number of protons or charge

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2
Q

What is the mass number?

A

The number of protons and neutrons combined

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3
Q

What is an isotope?

A

Atoms that have the same number of protons but a different number of neutrons

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4
Q

What is the format for the element symbol?

A

(A/Z) X

X: Element symbol
A: Mass number(The number of protons and neutrons combined)
Z: Atomic Number(number of protons)

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5
Q

What is atomic mass?

A

The average of all possible isotopes

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6
Q

What is the purpose of nuclear equations?

A

Nuclear equations can be used to represent nuclear interactions(ex. disintegration or transmutation of a nucleus)

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7
Q

The original isotopes are called the ___________(1). The final isotopes are called the __________(2).

A

(1) parent isotopes
(2) daughter isotopes

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8
Q

What two quantities must be conserved in a nuclear reaction?

A

Electric charge and the number of nucleons(protons and neutrons).

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9
Q

What is the nuclear notation for a proton, neutron, electron, and alpha particle?

A

Refer to notebook

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10
Q

An atomic mass unit is defined as __________________________(1).

A

(1) exactly 1/12th the mass of carbon-12

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11
Q

What is the mass defect? How do you calculate (delta)m?

A

When scientists compared the theoretical mass of helium-4 to its actual mass, they found a mass defect.

(delta)m = m(theoretical)-m(actual)

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12
Q

What is binding energy?

A

Strong repulsive electrostatic forces exist between protons in the nucleus. To hold the nucleus together, a large amount of binding energy is needed. this binding energy is equivalent tot eh mass defect, and is expressed by Einstein’s mass-energy equivalence theory.

The binding energy is also denied as the energy required to remove a nucleon from the nucleus.

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13
Q

What does the conservation of mass-energy state?

A

Conservation of mass and energy are aspects of one law since mass and energy are interconvertible. The conservation of mass energy allows us to imagine the creation of particles from kinetic or radiant energy(light energy) and the annihilation of particles into radiant energy.

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14
Q

What is induced nuclear transmutation?

A

The disintegration of a stable nucleus by striking it with another nucleus, an atomic or subatomic particle, or a gamma ray photon. This process can produce transuranium elements(elements that do not naturally occur) such as Np, Pu, Am.

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15
Q

What occurs in fusion?

A

SMALL TO BIG

  • Forming larger atoms by forcing lighter atoms together
  • Requires extremely high temperatures and pressures to bring multiple parent nuclei together so that the electrostatic force of repulsion is overcome and strong nuclear force takes over(once you get the 2 molecules close enough)
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16
Q

What is fission?

A

BIG TO SMALL

  • The process of bombarding a large nuclei with neutrons to produce smaller nuclei
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17
Q

Give an example of fusion.

A

Refer to notebook

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18
Q

Give an example of include nuclear transmutation.

A

Refer to notebook

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19
Q

Give an example of fission.

A

Refer to notebook

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20
Q

What is the process of fission?

A

If an incoming neutron is at the right energy level, it will enter the nucleus, cause it to oscillate uncontrollably, and split the nuclei.

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21
Q

Why does a neutron initiate a fission reaction?

A

A neutron doesn’t experience a repulsive electrostatic force

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22
Q

What happens if the incoming neutron is too fast or too slow, when trying to initiate a fission reaction?

A

If the incoming neutron is too energetic, it will pass through the target nuclei. If it is too slow, it will bounce off the target nucleus.

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23
Q

How is a fission reaction a chain reaction?

A

The product of a fission reaction includes a few neutrons(1-3). These neutrons invade new uranium-235 nuclei and continue the fission reaction. The reaction is referred to as self propagating.

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24
Q

What are the problems with fission?

A

(a) Fissionable uranium-235 is rare. Only 0.71% of all uranium is uranium-235. Other uranium isotopes will not produce a chain reaction.

(b) The process produces a vast amount of deadly radioactive material(krypton and barium) that must be properly stored.

(c) Reactors are subject to mechanical or human error which can be catastrophic(ex. Chernobyl)

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25
Q

Fission produces _________(1) as a product and fusion produces _____________(2) as a product.

A

(1) Energy
(2) Heat

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26
Q

How can the energy released through fission be calculated? Expand the formula.

A

Refer to notebook.

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27
Q

What is radioactive decay?

A

Radioactive decay occurs when unstable elements decay spontaneously, releasing alpha or beta particles, or gamma rays

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28
Q

What are alpha particles?

A

Alpha particles are the nuclei of helium atoms. They have a range of only a few cm in air, and can be stopped by an ordinary sheet of aluminum foil. Alpha particles are ejected at high speeds

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29
Q

What are beta particles?

A

Beta particles are high energy electrons ejected from a nucleus. They can penetrate several cm of aluminum foil. Beta particles are ejected at high speeds.

30
Q

The more ________(1) in the nucleus, the more _________(2) the atom will be.

A

(1) protons
(2) unstable

31
Q

What are gamma rays?

A

Photons with very short wavelengths and high frequency and higher energy. They behave more like discrete particles, and are hard to diffract. High energy gamma rays can penetrate at least 30 cm of lead and 2km of air.

32
Q

When alpha particles, beta particles, and gamma rays are sent through an external magnetic field, what happens?

A

Gamma ray: high energy EMR, no deflection occurs

Alpha particles: follow uniform circular motion, direction dependant on third hand rule

Beta particles: follow uniform circular motion, direction dependant on third hand rule

Radius of deflection is greater for an alpha particle than a beta particle. Alpha particle has more mass, more inertia, and its harder to change its momentum

33
Q

What is a radioactive decay series?

A

When a radioactive isotope undergoes decay, the resulting isotope is often radioactive as well. The series of nuclear reactions required to reach a stable isotope is referred to as a nuclear decay series/radioactive decay series.

34
Q

What is alpha decay? What is the formula

A
  • An atom decays and releases alpha particles
  • A mass defect exists between the mass of the parent nucleus and the sum of the daughter nucleus and alpha particle
  • According to the law of conservation of mass-energy, the energy equavalence of the mass defect should be equal to the kinetic energy of the alpha particle

E(k alpha) = (delta)m c^2

35
Q

What is beta decay?

A

Beta particles are produced when a neutron in the nucleus is converted into a proton. Formula in notes.

The problem is that the kinetic energy of the beta particles is always less than that of the predicted amount using conservation of mass energy. Formula in notes.

The only explanation is that there must be a second mysterious particle which acts as an energy carrier.

36
Q

What is beta positive decay? Write the formula.

A

Involves the transformation of a proton into a neutron and a positron(anti-electron). Also produces a neutrino

Formula in notes

37
Q

What is beta negative decay? Write the formula.

A
  • Involves the transformation of a neutron into a proton and an electron. Also produces an antineutrino.

Formula in notes

38
Q

What are high energy particle accelerators?

A

High energy particle accelerators fire high speed particles at different nuclei. They allow scientists to probe the structure of the nucleus and determine what types of subatomic particles it is composed of.

39
Q

What are probe particles?

A

High energy particles that break up a nucleus. They are able to overcome the strong nuclear force and provide the energy needed to create matter(calculated by E=mc2)

40
Q

What is pair production? Write the formula.

A

ENERGY TO MATTER

Firing a high energy photon at a nucleus will produce an electron-positron pair. Has to be a pair to uphold conservation of charge.

Formula in notes

41
Q

What is pair annihilation? Write the formula.

A
  • MATTER TO ENERGY

When a particle meets an antiparticle, they annihilate one another and release a pair of gamma ray photons. This explains why antimatter does not exist in nature.

Formula in notes

42
Q

What are cloud chambers?

A
  • GAS TO LIQUID
  • Contain a gas supersaturated with a vapour from a liquid
  • When a high energy CHARGED particle passes through the chamber, it will condense the gas, leaving vapour trails
43
Q

What are bubble chambers?

A
  • LIQUID TO GAS
  • Contain liquid hydrogen at less than -252.8 degrees celsius
  • When a high energy particle or photon(DOES NOT NEED TO BE CHARGED) passes through the shamble, it will vaporize the hydrogen produce bubbles
  • High energy particle breaks bond between H2, the positive and negative H are attracted to each other to reform the bond, this releases heat into the chamber. Increasing T creates gaseous hydrogen in liquid, thus forming a trail of bubbles
44
Q

_________________(1) applied magnetic fields across the chambers to determine the ___________________(2) of the particles by deflecting them.

A

(1) Carl Anderson
(2) charge to mass ratio

45
Q

Subatomic particles move in a spiral because _____________________(1). Another explanation is that ______________________(2)

A

(1) they are giving off energy to break the hydrogen bonds
(2) the accelerating charges are producing EMR and losing energy

46
Q

What is decay rate? What is the equation used to determine decay rate? Define all the variables.

A

Radioactive elements do not decay all at once/at the same time. Decay rate is the rate at which a parent isotope turns into a daughter isotope. Decay rate is government by an exponential equation(refer to notebook)

47
Q

1Bq = ?

A

1 decay/ s, or the number of nuclei that change in a given period of time. N and N(o) can be expressed in units of mass or Bq

48
Q

A half life is the time it takes for ___________________________(1) and the _____________________(2).

A

(1) half of the parent isotope to decay into the daughter isotope
(2) radioactivity level to decrease by 1/2

49
Q

What does the slope on a decay curve tell you? What are the labels on the x and y axis?

A

The slope tells you decay activity(decay/s).
x axis: time
y axis: number of parent nuclei remaining

50
Q

_______________(1) are the mechanism by which the fundamental forces act over the distance between particles. These particles are called __________(2) because they cannot be directly deflected by a particle detector.

A

(1) mediating particles
(2) virtual

51
Q

What are the four fundamental forces?

A
  1. Gravitational forces
  2. Electrostatic/Electromagnetic forces
  3. Strong Nuclear Forces
  4. Weak nuclear force
52
Q

What is a gravitational force?

A
  • Always attractive between matter
  • Acts over an unlimited range
  • By far the weakest of all forces
  • Mediator: Gravitons
53
Q

What is the electromagnetic force?

A
  • Attractive or repulsive force between charges
  • Acts over an unlimited range
  • Much stronger than the gravitational force
  • Mediator: Photons
54
Q

What is the strong nuclear force?

A
  • Holds protons and neutrons together in the nucleus
  • Extremely powerful over a short effective range
  • Mediator: Gluons
55
Q

What is the weak nuclear force?

A
  • Converts protons to neutrons(and vice versa)
  • Beta negative decay
  • Larger effective range than strong nuclear force
  • Mediators: W+(beta positive decay), W-(beta negative decay), Z(degrees)
56
Q

What three categories are all subatomic particles grouped under?

A
  1. Photos: interact by means of the electromagnetic force
  2. Hadrons: Heavier particles(ie. protons, neutrons) that interact primarily by means of the strong nuclear force
  3. Leptons: Lighter particles(ie. electrons, neutrinos) that cannot interact by means of the strong nuclear force. Have a smaller mass than hadrons
57
Q

What is spin?

A

A quantum property resembling rotational angular momentum that is also used to group particles

  1. Fermions: Half integer spins, include leptons and baryons
  2. Bosons: Integer spins that include mediating particles and mesons(a hadron)
58
Q

What does quark theory state?

A

All hadrons(ie. protons and neutrons) are made up of a cluster of two or more particles called quarks

59
Q

What are the main properties of quarks?

A
  • Quarks interact primarily via the strong nuclear force
  • There are 2 main flavours of quarks and antiquarks: up and down
60
Q

Explain spin and quarks.

A

Each quark and antiquark has a spin of 1/2. Quark spin adds up to the spin of the composite particle.

61
Q

Explain charge and quarks.

A

Each quark has a fractional charge. When quark charges are added together, the result is an integer charge. Quarks cannot be isolated

62
Q

Draw the quark composition of a proton and neutron

A

proton: uud
neutron:udd

63
Q

Hadrons are divided into which two groups?

A
  1. Baryons: Hadrons with a half integer spin. A baryon is composed of 3 quarks. Antibaryons are composed of three antiquarks
  2. Mesons: Hadrons with an integer spin. Composed of one quark and antiquark
64
Q

Explain beta decay with quarks.

A
  • Involves the emission of a lepton(electron or positron)
  • Must proceed via the weak nuclear force
65
Q

Explain beta negative decay with quarks.

A
  • A down quark in a neutron turns into an up quark by emitting a virtual W- particle(mediator for weak force) The W- particle decays into an electron and antineutrino. The formula is in notes
66
Q

Explain beta positive decay with quarks.

A

An up quark in a proton turns into a down quark by emitting a virtual W+ particle. The W+ particle decays into a positron and neutrino. The formula is in notes.

67
Q

What is the standard model?

A

the standard model refers to the currently accepted explanation for the strong and weak nuclear and the electromagnetic fore

  1. All matter is composed of 12 fundamental particles: 6 leptons and 6 quarks(plus their antiquarks).
  2. The electromagnetic and nuclear forces are mediated by virtual particles.
  3. The weak nuclear and electromagnetic force are both aspects of a single fundamental force(Theory of electroweak interaction)
  4. The strong nuclear force between quarks described in the concept of colour change(theory of quantum chromodynamics)
68
Q

What is a neutrino?

A
  • A massless particle with no charge
  • represented with v
  • Existence of neutrinos is supported by law of conservation of momentum, angular momentum, and mass-energy
69
Q

In nuclear reactions: Sum of momentum of atoms before the reaction is qual to the sum of the momentum of atoms after the reaction

A

random note

70
Q

What is gamma radiation?

A
  • Nuclei also have a series of excitation energy levels
  • In excited states, the nucleons are further apart and have greater binding energy
  • When a nuclei undergoes alpha or beta decay, the daughter nucleus is often left in a highly excited state
  • As the excited nuclei makes a transition back to its ground state, it emits a gamma ray photon

formula in notes

71
Q

What is antimatter?

A

Same mass but opposite charge

Physics 30 (8 decks)

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