Unstable Nuclei and Radioactive Decay (Video Notes)

Vocabulary flashcards covering unstable nuclei, radioactive decay, fission, fusion, and related nuclear concepts from the video notes.

Unstable nucleus

A nucleus that is not in a stable state and may undergo radioactive decay, releasing radiation.

Radioactive decay

The process by which an unstable nucleus transforms into a different nucleus by emitting radiation.

Alpha particle

A helium-4 nucleus consisting of 2 protons and 2 neutrons; charge +2.

Alpha decay

A type of radioactive decay in which the nucleus emits an alpha particle, reducing mass by 4 and atomic number by 2.

Nuclear equation

A symbolic equation showing changes in nuclear composition while balancing mass and atomic numbers.

Mass number

Total number of protons and neutrons in a nucleus; symbol A.

Atomic number

Number of protons in the nucleus; defines the element; symbol Z.

Balancing mass and atomic numbers

In a nuclear reaction, the total mass numbers and total atomic numbers must be equal on both sides.

Beta particle

An electron emitted from a nucleus during beta decay (beta minus); symbol β−.

Beta decay

A process where a neutron becomes a proton with emission of a beta particle, increasing atomic number by 1.

Positron

The positively charged counterpart of the electron; emitted in beta plus decay (positron emission).

Positron emission

A nuclear process where a proton converts to a neutron with emission of a positron, decreasing atomic number by 1.

Nuclear fission

Splitting of a large nucleus into two smaller nuclei, releasing large amounts of energy.

Nuclear fusion

Two light nuclei combine to form a heavier nucleus; releases energy; fusion releases more energy per mass than fission.

Chain reaction

A self-sustaining series of fissions triggered by neutrons produced in fission; requires sufficient nearby fissile material.

Fissile isotope

An isotope capable of sustaining a chain reaction (e.g., Uranium-235).

Neutron

A neutral subatomic particle that can initiate fission when absorbed by fissile nuclei.

Particle accelerator

A device used to accelerate particles to high speeds to bombard nuclei in nuclear reactions.

Nuclear reaction

A process that changes the nucleus of atoms, such as decay, fission, or fusion.

Uranium-235

A fissile isotope used to sustain chain reactions in nuclear reactors.