Nuclear Physics!

What are the properties of the strong nuclear force?

1) It has a small range 2) the force must act between nucleons. 3) must be a force of repulsion when the nucleons are close together. 4) The resultant force on any neutron is the strong force acting on it. 5) The resultant force on any proton is the vector sum of the strong force and the electrical force.

What are the 3 main types of *radioactive decay*?

1. alpha decay 2. beta decay (and positron emission) 3. gamma decay Sometimes positron emission is categorized as its own thing.

What is a *beta particle*?

A high-speed electron.

What is the general process in an artificial fission reaction?

A neutron is shot at a large atom, which absorbs the neutron, which makes it unstable, and so it splits into smaller atoms, releasing energy and more neutrons, which go on to split more atoms. It's a chain reaction.

Alpha particle

A positively charged particle made up of two protons and two electrons

What is *fission*?

A reaction in which a nucleus splits into two are more nucleiand releases neutrons and a lot of energy.

What is *fusion*?

A reaction in which nuclei combine and a lot of energy is released.

What is an *electron*?

A subatomic particle that is negatively charged.

What is a *neutron*?

A subatomic particle that is neutrally charged.

What is a *proton*?

A subatomic particle that is positively charged.

What is a *gamma ray*?

A very high-energy electromagnetic wave that has no charge and no mass.

During b+ decay A) a proton is transformed to a neutron. B) a neutron is transformed to a proton. C) a proton is ejected from the nucleus. D) a neutron is ejected from the nucleus.

A) a proton is transformed to a neutron.

A nucleon is either A) a proton or a neutron. B) a neutron or an electron. C) a positron or an electron. D) a proton or an electron.

A) a proton or a neutron.

The hydrogen nucleus consists of A) a single proton. B) one proton and two neutrons. C) one proton and one neutron. D) a single neutron.

A) a single proton.

In beta decay A) an electron is emitted. B) an electron decays into another particle. C) a neutron is emitted. D) a proton is emitted.

A) an electron is emitted.

A β- particle is also known as A) an electron. B) a photon. C) a helium nucleus. D) a positron.

A) an electron.

When an atom undergoes nuclear transmutation, the result is a completely different A) atom of a different element B) atom of the same element C) isotope of the same element. D) ion of the same element.

A) atom of a different element

The binding energy per nucleon A) has a maximum near iron in the periodic table. B) is approximately constant throughout the periodic table, except for very light nuclei. C) increases steadily as we go to heavier elements. D) decreases steadily as we go to heavier elements.

A) has a maximum near iron in the periodic table.

Atoms with the same atomic number but with different numbers of neutrons are referred to as A) isotopes. B) nuclides. C) nucleons. D) none of the given answers

A) isotopes.

In radioactive dating, carbon-14 is often used. This nucleus emits a single beta particle when it decays. When this happens, the resulting nucleus is A) nitrogen-14. B) still carbon-14. C) boron-14. D) carbon-15. E) carbon-13.

A) nitrogen-14.

The half-life on an isotope is one day. At the end of three days, how much of the isotope remains? A) one-eighth B) none of these C) none D) one-quarter E) one-half

A) one-eighth

The atomic number of an element is the same as the number of its A) protons. B) neutrons. C) none of these D) nucleons.

A) protons.

What is the binding energy of a nucleus? A) the energy released when nucleons bind together to form a stable nucleus B) the mass of the nucleus times c C) the energy needed to remove one of the nucleons D) the average energy with which any nucleon is bound in the nucleus

A) the energy released when nucleons bind together to form a stable nucleus

Most of the radioactivity we personally encounter comes from A) the natural environment. B) nuclear power plants. C) fallout from past and present testing of nuclear weapons. D) medical X rays.

A) the natural environment.

What does the mass number of a nucleus indicate? A) the number of neutrons and protons present B) the number of protons present C) the number of neutrons present D) the average atomic mass of the element

A) the number of neutrons and protons present

To which of the following is the atomic number of a given element equivalent? A) the number of protons in the nucleus B) the number of electrons in the outer shells C) the sum of the protons and neutrons in the nucleus D) the number of neutrons in the nucleus

A) the number of protons in the nucleus

Which of the following is most nearly the same as a gamma ray? A) visible light B) a neutron C) a proton D) an alpha particle E) a beta ray

A) visible light

What is an *alpha particle*?

An alpha particle consists of 2 protons and 2 neutrons, they are generally produced through alpha decay

What is an *isotope*?

An atom that has the same number of protons but a different number of neutrons.

What is an *atomic mass unit* (u)?

An easy-to-use unit for measuring very small masses, like those on an atomic scale.

beta particle

An electron emitted by an unstable nucleus

What makes an element *radioactive*?

An unstable nucleus that breaks down and emits particles and energy as a result.

Why are elements with high atomic numbers (above 83) radioactive (spontaneously decay)?

As the number of protons increases, there is a tipping point at which the additional strong nuclear force that comes from adding more neutrons isn't enough to balance the repulsive force that protons exert on each other. This is mostly because the strong nuclear force has such a short range.

What happens to the half-life of a radioactive substance as it decays? A) It could do any of these. B) It remains constant. C) It decreases. D) It increases.

B) It remains constant.

An element will decay to an element with higher atomic number in the periodic table if it emits A) none of these B) a beta particle. C) an alpha particle. D) a proton. E) a gamma ray.

B) a beta particle.

A gamma ray is also known as A) a positron. B) a photon. C) an electron. D) a helium nucleus.

B) a photon.

Alpha rays can penetrate, at most A) several centimeters of lead. B) a piece of paper. C) several millimeters of aluminum. D) air only.

B) a piece of paper.

A b+ particle is also known as A) a helium nucleus. B) a positron. C) an electron. D) a photon.

B) a positron.

When a b+ particle is emitted from an unstable nucleus, the atomic number of the nucleus A) none of the given answers B) decreases by 1. C) increases by 1. D) does not change.

B) decreases by 1.

When an alpha particle is emitted from an unstable nucleus, the atomic mass number of the nucleus A) increases by 4. B) decreases by 4. C) increases by 2. D) decreases by 2.

B) decreases by 4.

When a b- particle is emitted from an unstable nucleus, the atomic mass number of the nucleus A) decreases by 1. B) does not change. C) increases by 1. D) none of the given answers

B) does not change.

When a b- particle is emitted from an unstable nucleus, the atomic number of the nucleus A) does not change. B) increases by 1. C) none of the given answers D) decreases by 1.

B) increases by 1.

Generally speaking, the larger a nucleus is, the greater its A) none of these B) instability. C) stability. D) permeability

B) instability.

An alpha particle will be attracted to a A) positive charge. B) negative charge. C) proton. D) gamma ray.

B) negative charge.

A gram of radioactive material has a half-life of one year. After 4 years, how much radioactive material will be left? A) 0 g B) none of these C) 1/4 g D) 1/2 g E) 1/8 g

B) none of these

When a gamma ray is emitted from an unstable nucleus, A) the number of neutrons drops by one and the number of protons increases by one. B) there is no change in either the number of neutrons or the number of protons. C) the number of neutrons and the number of protons drop by two. D) none of the given answers

B) there is no change in either the number of neutrons or the number of protons.

Why does the number of neutrons need to be greater than or equal to the number of protons in order to have a stable nucleus?

Because the strong nuclear force that attracts protons and neutrons to each other has a much shorter range than the repulsive force that the protons experience. Protons are repelled by all of the other protons in the nucleus because they're like charges. Compared to this repulsive force, the strong nuclear force has a very short range - it only attracts things that are next to each other. So as the number of protons increases, the number of neutrons needs to increase even more to make up for the short range of the strong nuclear force.

During b- decay A) a neutron is ejected from the nucleus. B) a proton is transformed to a neutron. C) a neutron is transformed to a proton. D) a proton is ejected from the nucleus.

C) a neutron is transformed to a proton.

Which particle has the most mass? A) beta B) gamma C) alpha D) electron

C) alpha

When an alpha particle is ejected from a nucleus, the nucleus then has less A) mass. B) neither of these C) both of these D) charge.

C) both of these

When a nucleus emits a beta particle, its atomic number A) none of these B) remains constant, but its mass number changes. C) changes, but its mass number remains constant. D) changes, and so does its mass number. E) remains constant, and so does its mass number.

C) changes, but its mass number remains constant.

When an alpha particle is emitted from an unstable nucleus, the atomic number of the nucleus A) increases by 2. B) increases by 4. C) decreases by 2. D) decreases by 4.

C) decreases by 2.

When a gamma ray is emitted by a nucleus, the nucleus then has less A) charge. B) neither of these C) energy. D) both of these

C) energy.

When a nucleus emits a beta particle, its atomic number A) increases by 2. B) decreases by 2. C) increases by 1. D) decreases by 1. E) none of these

C) increases by 1.

Compared to the electrostatic force, the nuclear force between adjacent protons in a nucleus is A) about the same size. B) much weaker. C) much larger. D) only slightly larger.

C) much larger.

Different isotopes of an element have different numbers of A) photons. B) protons. C) neutrons. D) hadrons. E) none of these

C) neutrons.

The atomic mass unit is defined as A) the mass of an electron. B) the mass of a hydrogen-1 atom. C) one twelfth the mass of a carbon-12 atom. D) the mass of a proton.

C) one twelfth the mass of a carbon-12 atom.

The half-life of an isotope is one day. At the end of two days the amount that remains is A) one-eighth. B) none of these C) one-quarter. D) one-half. E) none.

C) one-quarter.

Electric forces within an atomic nucleus tend to A) spin the electrons B) hold it together. C) push it apart. D) none of these

C) push it apart.

When nucleons join to form a stable nucleus, energy is A) absorbed. B) destroyed. C) released. D) not transferred.

C) released.

Gamma rays can penetrate, at most A) air only. B) a piece of paper. C) several centimeters of lead. D) several millimeters of aluminum.

C) several centimeters of lead.

Beta rays can penetrate, at most A) several centimeters of lead. B) air only. C) several millimeters of aluminum. D) a piece of paper.

C) several millimeters of aluminum.

A certain radioactive isotope placed near a Geiger counter registers 160 counts per second. Eight hours later, the counter registers 10 counts per second. What is the half life of the isotope? A) 8 hours B) 4 hours C) 6 hours D) 2 hours E) none of these

D) 2 hours

Alpha particles have an atomic mass equal to A) 1. B) 6. C) 2. D) 4.

D) 4.

If an atom's atomic number is given by Z, its atomic mass by A, and its neutron number by N, which of the following is correct? A) none of the given answers B) N = Z - A C) N = A + Z D) N = A - Z

D) N = A - Z

Control is exercised in a nuclear reactor by A) emitting fast neutrons with a moderator. B) both of these C) none of these D) absorbing excess neutrons with control rods.

D) absorbing excess neutrons with control rods.

When a beta particle is ejected from a nucleus, the nucleus then has a greater A) neither of these B) mass. C) both of these D) charge.

D) charge.

When a neutron is emitted from an unstable nucleus, the atomic mass number of the nucleus A) none of the given answers B) increases by 1. C) does not change. D) decreases by 1.

D) decreases by 1.

Which of the atomic particles has the least mass? A) nucleon B) proton C) neutron D) electron

D) electron

The number of protons in an atom is A) the same for all elements. B) zero. C) equal to the number of neutrons. D) equal to the number of electrons.

D) equal to the number of electrons.

Of the main types of radiation emitted from naturally radioactive isotopes, which is the most penetrating? A) beta B) positron C) alpha D) gamma

D) gamma

Compared to the masses of its separate protons and neutrons, the total mass of a stable nucleus is always A) the same. B) greater. C) zero. D) less.

D) less.

The binding energy of a nucleus is contributed to A) alpha decay. B) too many neutrons. C) radioactivity. D) mass defect.

D) mass defect.

Which process generates energy in the Sun? A) transmutation B) nuclear fission C) chain reaction D) nuclear fusion

D) nuclear fusion

An atom's mass number is determined by the number of A) protons in its nucleus. B) alpha particles in its nucleus. C) neutrons in its nucleus. D) nucleons in its nucleus.

D) nucleons in its nucleus.

The nucleus of an atom is made up of which of the following combinations of particles? A) electrons and neutrons B) protons, electrons, and neutrons C) electrons and protons D) protons and neutrons

D) protons and neutrons

An atom's atomic number is determined by the number of A) neutrons in its nucleus. B) alpha particles in its nucleus. C) nucleons in its nucleus. D) protons in its nucleus.

D) protons in its nucleus.

When a beta particle is ejected from a nucleus, the nucleus then has slightly A) greater mass and smaller charge. B) greater mass and charge. C) smaller charge and significantly greater mass. D) smaller mass and significantly greater charge.

D) smaller mass and significantly greater charge.

There is a limit to the size of a stable nucleus because of A) the weakness of the electrostatic force. B) none of the given answers C) the weakness of the gravitational force. D) the limited range of the strong nuclear force.

D) the limited range of the strong nuclear force.

Isotopes of an element have nuclei with A) a different number of protons, and a different number of neutrons. B) a different number of protons, and the same number of neutrons. C) the same number of protons, and the same number of neutrons. D) the same number of protons, but different numbers of neutrons.

D) the same number of protons, but different numbers of neutrons.

An atom with an imbalance of electrons to protons is A) an isotope. B) a hadron. C) a baryon. D) none of these E) an ion.

E) an ion.

Which radiation has no electric charge associated with it? A) all of these B) none of these C) alpha rays D) beta rays E) gamma rays

E) gamma rays

Which subatomic particle determines the *ion* of an element?

Electrons.

Nuclear power plants conduct which kind of reaction: fission or fusion?

Fission.

If a nucleus has only protons and neutrons, then where does the electron come from during beta decay?

From a neutron. A neutron is a proton and an electron bound together.

Where does *nuclear binding energy* come from?

From the mass of protons and neutrons. Protons and neutrons give up a little bit of their mass when they form a nucleus. This little bit of mass is converted into the binding energy that holds the nucleus together.

Which reaction generally releases more energy: fission or fusion?

Fusion.

What is a *positron*?

Like an electron, except it has a positive charge. (It's NOT a proton because it has negligible mass.))

How is binding energy related to the stability of a nucleus?

More stable nuclei have higher binding energies - it requires more energy to break apart stable nuclei.

Which subatomic particle determines the *isotope* of an element?

Neutrons.

Where does the *strong nuclear force* come from?

Nuclear binding energy.

Which subatomic particles make up the nucleus?

Protons and/or neutrons.

Which subatomic particle determines the *identity* of an element?

Protons.

How is the ratio of protons to neutrons related to the stability of a nucleus?

Ratios that are closer to 1:1 are more stable. There needs to be at least as many neutrons as protons for a stable nucleus.

How do protons stay together in the nucleus if like charges repel? Why don't they fly apart?

The *strong nuclear force* holds the protons together. It's stronger than the repulsive force that protons feel from being like charges.

What happens to the nuclear binding energy when a nucleus is split?

The energy is released as heat.

What is the Strong Nuclear Force?

The force between nucleons that holds the nucleus together. All particles that contain quarks can interact via the strong nuclear force.

What is the *mass number* (A)?

The number of protons and neutrons in an atom. (Electrons don't count because they have so little mass compared to protons and neutrons.)

What is the *atomic number* (Z)?

The number of protons in an atom.

How are the mass number and the atomic number represented in chemical symbol form?

Top = mass number (protons + neutrons) Bottom = atomic number (protons)