Colloidal refers to items of a small size that are floating in a medium of one of three substances: a solid, a liquid, or a gas. Colloidal particles can be suspended in a substance just like their own make-up or a different substance with the exception of gases. Gas particles will not suspend in another gas.
Colloids can be expressed in a word which is ‘colloid’ or by the phrase colloidal solution. When using the word ‘colloid’ for the purpose of chemistry and the different elements that make up the field the word colloid can be used as either an adjective, thereby stating that the item in question has the correct properties to be considered colloidal, or, a noun to mean the object in question is a colloidal solution.
Colloidal solutions contain particles that measure from 10 to 10,000 angstroms. Each angstrom of a particle is equal to one ten billionth of a meter of length. An Angstrom is similar to the nanometer which is one billionth of a meter, and, the smallest recognized unit on the international unit scale known as the SI scale with the initials SI standing for System of Units, International. Both measuring units are used for expressing measurements of length or dimension of tiny units like molecules, or, atoms which are what make up the molecules in quantities of at least two or more atoms per molecule, that you might find in chemistry. These are the same units used for the measuring of bacteria, atoms and other scientific matter that are often microscopic, as well. When using the angstrom you can express the size of the tiniest of objects including the lengths of chemical bonds, electromagnetic radiation wavelengths and distances between the atoms in crystalline atoms and many more items.
Colloids are common in science, many regular objects and substances are colloids and others can be made in to colloidal solutions for beneficial usages. Some of the common colloids include fog, hair spray or mist which are gas particles suspended in a liquid; whipped cream – a liquid suspended in a gas; hand cream – a liquid suspended in a liquid; pigmented ink or blood – liquid particles embodied in a liquid; Styrofoam – solid in a gas; jelly – solid in a liquid and cranberry glass – solid in a solid.
It can be confusing to distinguish some colloids from solutions so to do this a membrane test can be performed. If the solution will pass through the membrane, the membrane being an animal membrane, it is a solution. If the solution will not pass through the membrane is is a colloidal solution.