Chemistry Chapter 9

What is an alpha particle?

A type of radioactive decay particle consisting of 2 protons and 2 neutrons (a helium nucleus, 4 He). It has low penetration and can be stopped by paper.

What is background radiation?

Radiation that is naturally present in the environment from sources like cosmic rays, soil, and radon gas.

What is the band of stability?

A graph showing the stable ratio of neutrons to protons in atomic nuclei, where stable isotopes lie.

What is a beta particle?

A high-energy electron (β−) or positron (β+) emitted during radioactive decay. It has moderate penetration, stopped by aluminum.

What is nuclear binding energy?

The energy required to separate the nucleons of an atom's nucleus. It explains the mass defect and nuclear stability.

What is a nuclear chain reaction?

A self-sustaining process where released neutrons from nuclear fission cause further fission reactions.

What are control rods in a nuclear reactor?

Rods made of neutron-absorbing materials (like boron or cadmium) that regulate the fission reaction rate.

What is critical mass?

The minimum amount of fissile material needed to maintain a nuclear chain reaction.

What is a curie?

A unit of radioactivity, defined as 3.7×10^10 disintegrations per second.

What is the electromagnetic force in the nucleus?

The force causing protons to repel each other due to their positive charge.

What is a fuel rod in a nuclear reactor?

A rod containing fissile material (e.g., uranium-235) used to sustain nuclear fission.

What is a gamma ray?

High-energy electromagnetic radiation emitted from a nucleus during radioactive decay. It has high penetration, requiring thick lead or concrete shielding.

What is a Geiger counter?

A device that detects ionizing radiation by measuring electric pulses caused by radiation interacting with gas.

What is half-life?

The time required for half of a radioactive sample to decay into stable atoms.

What is an ionization counter?

A radiation detector that measures ionized particles created by radioactive decay.

What is mass defect?

The difference between the total mass of nucleons in an atom and the actual mass of the nucleus, explained by E=mc^2.

What is a moderator in a nuclear reactor?

A material (e.g., water or graphite) that slows down neutrons to sustain fission.

What is nuclear fission?

A reaction where a large nucleus splits into smaller nuclei, releasing energy.

What is the nuclear force?

A strong force that holds protons and neutrons together in the nucleus, overcoming the repulsion of protons.

What is nuclear fusion?

A reaction where two light nuclei combine to form a heavier nucleus, releasing energy (e.g., in the Sun).

What is a nuclear reactor?

A system that controls nuclear fission reactions to generate energy.

What are nucleons?

The particles (protons and neutrons) found in the nucleus of an atom.

What is plasma?

A high-energy state of matter where electrons are separated from nuclei, found in stars and fusion reactors.

What is the primary loop in a nuclear power plant?

The closed system where coolant transfers heat from the reactor core.

What is a rad?

A unit measuring radiation absorbed dose (1 rad = 0.01 Gy).

What is radioactive decay?

The spontaneous breakdown of a nucleus, emitting radiation.

What is a radioactive decay series?

A sequence of radioactive decays where unstable isotopes transform into stable ones.

What is radioactivity?

The process where unstable atomic nuclei emit radiation.

What is a rem?

A unit measuring the biological effect of radiation (1 rem = 0.01 Sv).

What is a scintillation counter?

A device that detects radiation by measuring flashes of light produced when radiation interacts with a material.

What is the secondary loop in a nuclear power plant?

A separate water system that receives heat from the primary loop and converts it to steam to drive turbines.

What is the shell model of the nucleus?

A model describing nucleons arranged in energy levels within the nucleus, similar to electron shells.

What is a steam generator in a nuclear plant?

A device that converts heat from the reactor into steam to drive turbines.