Mindblown: a blog about philosophy.

Silica, compound of the two most abundant elements in Earth’s crust, silicon and oxygen, SiO2. The mass of Earth’s crust is 59 percent silica, the main constituent of more than 95 percent of the known rocks. Silica has three main crystalline varieties: quartz (by far the most abundant), tridymite, and cristobalite. Other varieties include coesite, keatite, and lechatelierite. Silica sand is used in buildings and roads in the form of portland cement, concrete, and mortar, as…

chemical compound Nitrate, any member of either of two classes of compounds derived from nitric acid, HNO3. The salts of nitric acid are ionic compounds containing the nitrate ion, NO–3, and a positive ion, such as NH4+ in ammonium nitrate. Esters of nitric acid are covalent compounds having the structure R―O―NO2, in which R represents an organic combining group, such as…

Semimetals (metalloids) and some nonmetallic elements form sulfides that are molecular or that have sulfide bridges in a polymeric structure. For example, silicon disulfide, SiS2, has a structure consisting of infinite chains of SiS4 tetrahedrons that share edges. (Each SiS4 tetrahedron consists of a central silicon atom surrounded by and bonded to four sulfur atoms.) Phosphorus forms a series of molecular sulfides that includes…

The alkali metals and alkaline-earth metals are the only sulfides that have any appreciable water solubility and that appear to be primarily ionic. In contrast, the sulfides of the copper and zinc families are some of the least-soluble compounds known. When water-soluble metal sulfides are heated in aqueous solution with elemental sulfur, solutions of so-called polysulfides are formed. These…

Most metals react directly with sulfur to form metail sulfides—i.e., compounds that contain a metal atom and the sulfide ion, S2−. In addition to direct combination of the elements as a method of preparing sulfides, they can also be produced by reduction of a sulfate by carbon or by precipitation from acidic aqueous solution by hydrogen sulfide, H2S, or from basic solution…

Sulfide, any of three classes of chemical compounds containing the element sulfur. The three classes of sulfides include inorganic sulfides, organic sulfides (sometimes called thioethers), and phosphine sulfides. Inorganic sulfides are ionic compounds containing the negatively charged sulfide ion, S2−; these compounds may be regarded as salts of the very weak acid hydrogen sulfide. Organic sulfides are compounds in which a…

A coordination compound is composed of one or more complex structural units, each of which has a central atom bound directly to a surrounding set of groups called ligands. The nomenclature of coordination compounds is based on these structural relationships.

An acid can be thought of as a molecule containing at least one hydrogen cation (H+) attached to an anion. The nomenclature of acids depends on whether the anion contains oxygen. If the anion does not contain oxygen, the acid is named with the prefix hydro- and the suffix -ic. For example, HCl dissolved in water is called hydrochloric acid. Likewise, HCN and…

Ionic compounds containing polyatomic ions A special type of ionic compound is exemplified by ammonium nitrate (NH4NO3), which contains two polyatomic ions, NH4+ and NO3−. As the name suggests, a polyatomic ion is a charged entity composed of several atoms bound together. Polyatomic ions have special names that are used in the nomenclature of the compounds containing them. Common polyatomic…

Binary molecular (covalent) compounds are formed as the result of a reaction between two nonmetals. Although there are no ions in these compounds, they are named in a similar manner to binary ionic compounds. The nomenclature of binary covalent compounds follows these rules: These examples show how the rules are applied for the covalent compounds formed by…