Refrigerants are chemical compounds in a liquid or gaseous state that absorb heat by evaporating at low temperatures, and pressures and reject heat by condensing at high temperatures and pressures.
In air conditioning and refrigeration systems, refrigerants are used to absorb heat from a space where it is not wanted (i.e. indoor environment) and expel it to a neutral environment (i.e. usually outdoors).
Any substance that experiences a change in state from a liquid to a gas (or vice versa) can be used as a refrigerant in a vapour/compression- type system.
Matter is anything that has weight and occupies space.
Substances and materials are forms of matter.
Materials are types of matter that are manufactured or built.
Substances are types of matter that consist of component parts.
In this text, we shall use the term substances to describe matter, as we are dealing with the type of matter called refrigerants and the components that make up refrigerants.
All matter (substances) consists of extremely small particles called molecules.
A molecule is the smallest particle a substance can be divided into and still retain the properties of that substance.
A molecule in turn is comprised of two or more atoms.
The atoms cannot be broken down during chemical processes.
Atoms can be divided into smaller particles called neutrons, protons and electrons.
The atom is the smallest particle known and it is here that the story of matter begins.
All matter consists of atoms or a combination of atoms.
Carbon is a substance because it is matter and an element because all the atoms of carbon are of the same type.
Sodium chloride (table salt) is a substance and a compound.
It is a substance because it is matter and a compound because atoms of different types have combined to form the substance sodium chloride.