chapter 8: The nucleus

Arrange the four fundamental interactions according to their strength on a small scale, with the weakest on top.

1. Gravitational 2. Weak 3.Em 4. Strong

Order in which power is produced in nuclear power plant

1. Nuke reactor generates heat 2. Heat removed by liquid 3. Hot water boils 4. Steam fed to turbine 5. Turbine powers electric generator

What are the fundamental interactions that govern all physical processes?

1. The em interactions acts on charged particles 2. The strong interaction produces forces that have very short ranges 3. The gravitational interaction is most significant on a large scale

What are two approaches being used to create successful fusion reactors

1. magnetic fields to contain reacting nuclei 2. laser beams to heat and compress fuel pellets

Describe the necessary conditions for a fusion reactor

1. temps of 100 million C or higher 2. high concentration of nuclei 3. Sufficient confinement time

How many kinds of quarks are there that make up all. known hadrons?

6

What is an antiparticle?

A particle that has the same mass as another particle and behaves similarly but has an electric charge that is opposite in sign.

What is the net result of both positron emission and electron capture?

A proton is changed to a neutron

Which of the following statements correctly describe the factors that affect the health of a human exposed to ionizing radiation?

A whole-body exposure or concentrated exposure can determine the severity of the health effects. The amount of a dose of ionizing radiation determines the severity of the health effects.

Describe alpha particles, beta particles, and gamma rays

Alpha particles : two protons and two neutrons Beta particles : electrons Gamma ray :high frequency em radiation

Describe annihilation and pair production.

Annihilation - particle and antiparticle meet and destroy each other. Pair production - Particle and antiparticle created from high energy gamma ray.

why isn't natural uranium (U-238) used in nuclear reactors?

Because it does not fission easily (ratio of U-235 to U-238 is too low and the more common U-238 doesnt fission easily)

The stability of the nucleus can be predicted by the ratio of the ______

Binding energy to the nucleon number

Describe the three nuclear disasters

Chernobyl - lack of containment shell let waste blow in wind. Three Mile Island - Failure in cooling system released waste Fukushima - Disruption in power and flooding caused cooling system fail = fuel rod melted = explosion

What is the decay of an atom?

Decay of an atom is when a nucleus emits an alpha or beta particle/gamma ray.

Which statement below best describes the distribution of half-lives?

Each radionuclide has its own unique half-life.

Identify the reasons why a uranium nuclear chain reaction might stop.

Ejected neutrons fail to strike more uranium-235 nuclei. All remaining uranium-235 nuclei have fissioned.

Describe a fuel rod and control rod.

Fuel rod --> long tube containing fissionable material Control rod --> long tube made of neutron absorbing material

How is nuclear fission different from nuclear fusion?

Fusion --> joining two light nuclei Fission --> splitting large nuclei into two smaller ones

Describe the types of radioactive decay.

Gamma decay : Nucleus has excess of energy and emits gamma rays to reduce energy Alpha decay : nuclei too large to be stable Beta decay : One of the neutrons in a nucleus with too many of them spontaneously turns into a proton and emits a proton

Which of the following statements correctly describe the different products of radioactive decay?

Gamma rays are high frequency em waves. alpha particles are the nuclei of helium atoms

Match each fundamental interaction to the process or situation in which it is important.

Gravitational - holds galaxies together EM - governs most chem reactions Weak - Governs behavior of individual neutrons; affects what isotopes are stable Strong - important when considering fusion reactions; determines binding energy

The proton and neutron are the most common hadrons, but hundreds of others are known

Hadrons that are lighter than protons are made of a quark and an antiquark. They rapidly decay into other particles, often protons and neutrons. They are composed of quarks.

Describe I-131 and Ce-137

I -131: half life of 8 days and causes thyroid cancer Ce - 137: Half life of 30 years, affects the whole body but its difficult to trace to specific cancers

Describe the reaction that is the foundation for current research into fusion as a source of energy.

Lithium absorbs energy from reaction and acts as heat source for electric generating system. The reactants are deuterium and tritium.

Why is hydrogen fusion a desireable energy source?

Little pollution and an ample supply of hydrogen.

Which of the following statements correctly describe neutrinos?

Neutrinos have virtually no mass and have no charge. A neutrino is produced when a nucleus undergoes beta decay.

Which of the following particles are examples of hadrons?

Neutrons and protons

Which element can be used as a nuclear fuel and is commonly produced during the normal operation of a uranium-fueld reactor?

Plutonium (Pu)

Describe a positrons and a neutrino

Positron : proton with negative charge neutrino : uncharge particle with extremely small mass

Which processes can occur if a nucleus has too many protons relative to the number of neutrons?

Positron emission Electron capture

What quarks are needed to make a neutron and protron

Protron - 2 up 1 down Neutron - 2 down 1 up

Which of the following statements correctly describe quarks?

Quarks have charges of ±1313e or ±2323e. Protons and neutrons are made of quarks. Quarks are an important part of the Standard Model of elementary particles.

Which of the following statements correctly describe the atomic number of an element?

The atomic number is equal to the number of protons in the nucleus. Each element has its own unique atomic number.

Which of the following statements correctly describe the particles that make up an atom?

The electrons are located outside the nucleus of an atom. The mass of an electron is negligible compared to the mass of a proton.

Which of the following are examples of nuclear energy?

The energy source for reactors that create electricity The energy that keeps the sun shining The energy source for some extremely destructive weapons

The proton and neutron are the most common hadrons, but hundreds of others are known. Select all the choices that describe these other particles.

They rapidly decay into other particles, often protons and neutrons. They are composed of quarks. Hadrons that are lighter than protons are made of a quark and an antiquark.

The half life of a nuclide is the time required for one half of the _______

Unstable nuclei to decay

What is enriched uranium?

Uranium that contains a higher percentage of 235U.

What causes a chain reaction in the fission of a nucleus?

When neutrons are released via fission, it collides with another nucleus causing further fission (chain reaction)

Describe nuclide notation

Z - atomic number (number of protons in the nucleus) X - chemical symbol (the element symbol found on periodic table) A - mass number (number of protons + neutrons)

What is used to slow down fission in neutrons?

a moderator

If a gamma ray creates an electron-positron pair as shown in the figure, then the energy of the gamma ray must be

at least as much as twice the mass of an electron times the speed of light

The most common unit, used to express mass and energy in nuclear physics is the_____ mass unit which represents 1.66 x 10-27 kg, and a _______ which represents 1.60 x 10-13 J.

atomic and MeV

The binding energy for an isotope can be calculated from the

difference in mass between the actual mass of the nucleus and the total mass of the individual nucleons

True statements about isotopes:

isotopes have different numbers of hydrogen atoms. isotopes have the same number of protons but a different number of neutrons.

Describe Leptons and Hadrons.

leptons - Not affected by strong interaction, no internal structure nor measured radii Hadrons - Affected by strong interaction, made of quarks, have finite size

When a nucleus is formed, its mass is ______ the total mass of the individual particles prior to interaction.

less than (because some energy is lost during binding)

Arrange these elementary particles by mass, from the least massive (top) to the most massive (bottom) : proton, electron, neutrino

neutrino , electron, proton

Other particles that can be ejected during radioactive decay include an electron that has a positive charge instead of a negative charge, which is called a(n)____ , and one with a very small mass and no charge, which is called a(n)______

positron and neutrino

What does a sievert measure?

radiation received by a human that has the same biological effects as those produced when 1 kg of body tissue absorbs 1 joule of x-rays or gamma rays

All elementary particles are classified as either leptons or hadrons. Leptons differ from hadrons in that they ______

seem to have no apparent size or internal structure are not affected by the strong interaction

Which state are most elements at room temp?

solid

To find the binding energy of the nucleus, one can take the mass of an atom and ______ it from the sum of the masses of the individual nucleons.

subtract

The ratio of the binding energy to the number of nucleons is a reflection of

the stability of the nucleus