Nuclear Physics

Flashcards about Nuclear Physics

Nucleus

The region of space at the center of the atom that contains all the atom's positive charge and almost all its mass.

Proton

Positively charged particle found in the nucleus of an atom.

Neutron

Electrically neutral particle found in the nucleus of an atom.

Nucleons

What is the collective term for protons and neutrons?

Nuclear Physics

The study of how nucleons interact with one another in a nucleus.

Atomic Number

Z

Neutron Number

N

Mass Number

A

How are mass number, neutron number, and atomic number related?

A = Z + N

Isotopes

Nuclei with the same number of protons but different numbers of neutrons.

Atomic Mass Unit (u)

A unit of mass exactly equal to 1/12 the mass of a carbon-12 atom.

According to Einstein, how are mass and energy related?

E = mc²

Strong Nuclear Force

The attractive force that holds a nucleus together.

Properties of the Strong Nuclear Force

Acts over a very short range, is always attractive, and acts with nearly equal strength on protons and neutrons, but not on electrons.

Radioactivity

The particles and photons emitted when a nucleus decays.

Alpha Particles (α)

Consist of two protons and two neutrons (helium nuclei).

Beta Particles (β-)

Electrons emitted during radioactive decay.

Positrons (β+)

The antiparticle to an electron (positive electron).

Gamma Rays (γ)

High-energy photons emitted when a nucleus drops to a lower-energy state.

Parent Nucleus

The nucleus before decay.

Daughter Nucleus

The nucleus remaining after decay.

What is the basic process that occurs in beta decay?

The conversion of a neutron to a proton, an electron, and an antineutrino.

Nuclear Fission

The process in which a large nucleus splits into two smaller nuclei.

What property must a substance have if it is to control a fission chain reaction?

Material that absorbs a portion of the neutrons produced by the reaction.

Nuclear Fusion

Two light nuclei combine to form a more massive nucleus.

Half-Life (T1/2)

The time required for half of the nuclei in a sample of a radioactive material to decay.

Formula for Elapsed Time Based on Activity

t = (T1/2 / 0.693) * ln(Rinitial / Rcurrent)

Becquerel (Bq)

1 becquerel = 1 Bq = 1 decay/s

Curie (Ci)

1 curie = 1 Ci = 3.7 X 10^10 decays/s

Coin flips

Nuclear decay is similar to _, each round of which cuts the number of coins in half.

How does carbon-14 dating work?

Measures the current carbon-14 activity in a sample from a once-living organism to estimate the time since death.

Nuclear Fission

A process in which a large nucleus splits into smaller nuclei.

Nuclear Fusion

A process in which two light nuclei combine to form a more massive nucleus.

Critical Nuclear Reactor

Occurs when, on average, one neutron given off by a fission reaction produces an additional reaction.

Curie

The unit used to measure activity.

Relative Strength of Strong Nuclear Force

1

Relative Strength of Electromagnetic Force

10^-2

Relative Strength of Weak Nuclear Force

10^-6

Relative Strength of Gravitational Force

10^-43

Hadrons

Particles that are acted on by both the weak and the strong nuclear forces.

Leptons

Particles that are acted on by the weak nuclear force but not by the strong nuclear force are referred to as:

Quarks

Particles that form mesons and baryons

Hadrons

Particles that act on both weak and strong nuclear forces and participate in all four fundamental interactions.

Annihilate

When they come into contact, particles of matter and their antiparticles ___ one another in a burst of energy.

E=mc^2

Mass and Energy relationship

Integer

Quarks are always bound in combinations that result in a net charge that is _ multiple of e