Aerogel is a manufactured material with the lowest bulk density of any known porous solid.[1] It is derived from a gel in which the liquid component of the gel has been replaced with a gas.

Aluminium hydroxide, Al(OH)3, Alum, is the most stable form of aluminium in normal conditions. It is found in nature as the mineral gibbsite (also known as hydrargillite) and its three, much more rare, polymorphs: bayerite, doyleite and nordstrandite.

In many items, moisture encourages the growth of mold and spoilage. Condensation may also damage other items like electronics and may speed the decomposition of chemicals, such as those in vitamin pills. By adding packets of silica gel, these items can be preserved longer.

Solid produced by the formation of a three-dimensional cage structure, commonly of linked large-molecular-mass polymers, in which a liquid is trapped. It is a form of colloid. A gel may be a jellylike mass (pectin, gelatin) or have a more rigid structure (silica gel).

Silicon dioxide, SiO2, the composition of the most common mineral group, of which the most familiar form is quartz. Other silica forms are chalcedony, chert, opal, tridymite, and cristobalite.

Magnesium sulfate (or magnesium sulphate) is a chemical compound containing magnesium, sulfur and oxygen, with the formula MgSO4. In its hydrated form the pH is 6.0 (5.5 to 6.5). It is often encountered as the heptahydrate, MgSO4·7H2O, commonly called Epsom salt.

Silicon dioxide, SiO2, the composition of the most common mineral group, of which the most familiar form is quartz. Other silica forms are chalcedony, chert, opal, tridymite, and cristobalite.

Silica gel is a granular, vitreous, highly porous form of silica made synthetically from sodium silicate. Despite its name, silica gel is a solid.