chemistry technology

A  systematic  nomenclature  was  devised  towards  the  end  of  the  18th  century.  Elements  already known  retained  their  old  names,  e.g.  silver,  tin,  gold,  mercury,  etc.,  but  newly  discovered  elements generally have their names ending in -um if they are metals, and-on if they are non-metals/e.g. sodium, potassium, argon /.
The  names  of  compounds  are  formed  from  those  of  their  components  so  as  to  indicate  their composition. In the names of binary compounds /i.e., compounds of two elements/ the name of the metal comes first, followed by that of the other element ended in -ide, e.g. sodium chloride /NaCl/, zinc oxide
/ZnO/, aluminum oxide /Al2O3/. When a metal forms two compounds with oxygen, the two oxides are distinguished  by  adding  -ous  and  -ic  to  the  Latin  name  of
 the  metal,  signifying  the  lower  and  higher oxidation  states  respectively,  e.g.,  cuprous  oxide  /Cu2O/,  cupric  oxide  /CuO/,  and  ferrous  oxide  /FeO/, ferric  oxide  /Fe2O3/.  The  salts  corresponding  to  cuprous  oxide  are  called  cuprous  salts,  e.g.  cuprous chloride and cupric chloride. Another way  of distinguishing between different compounds of the same element is by the use of the Greek prefixes to the names of the elements. These prefixes are as follows: mono-, di-, tri-, tetra-, penta-, hexa-, hepta-, octo-. To these we may add the Latin hemi-, meaning one half, and sesqui-, meaning one and a half, and per-. By the use of these prefixes we can designate the compounds more precisely than by means of the prefixes -ous and -ic, especially when more than two compounds exist. As examples of the use of these prefixes we may mention carbon monoxide /CO/ and carbon  dioxide  /CO2/,  phosphorus  trichloride  /PCl3/  and  phosphorus  pentachloride  /PCl5/,  chromium sesquioxide /Cr2O3/ and chromium trioxide /CrO3/, lead hemioxide /Pb2O/, hydrogen peroxide /H2O2/.
Oxides, which form salts with acids, are known as basic oxides; by combination with water, basic oxides form bases. These  contain the metal united  with the group of atoms -OH/ the hydroxyl group/; they are, therefore, called hydroxides. Thus NaOH is sodium hydroxide, Cu(OH)2  is copper hydroxide,
and the compounds Fe(OH)2  and Fe2O3.H2O are ferrous hydroxide and ferric hydroxide, respectively.
The endings -ous, -ic are also applied to acids, the -ous acid containing less oxygen than the -ic acid, e.g. sulphurous acid /H2SO3/ and sulfuric acid /H2SO4/, chlorous acid /HClO2/. In addition to HClO2 and HClO3, the acids having the formulas HClO and HClO4  are also known, the former having the name hypochlorous acid, the latter being designated by the name perchloric acid.
Salts  are  named  in  relation  to  the  acids  from which  they  are  derived  according  to  the  following
rules:
1. If the name of the acid ends in -ous, the name of the salt ends in -ite/ sodium chlorite, NaClO2/.
2. If the name of the acid ends in -ic, the corresponding salt ends in -ate/ sodium chlorate, NaClO3/
3. If the name of the acid involves also a prefix such as per- or hypo-, the prefix is retained on the name  of  the  salt/  sodium  hypochlorite,  NaClO,  and  sodium  perchlorate,  NaClO4/.  Accordingly, salts of sulfurous acid are called sulfites, those of sulfuric acid, sulfates. Salts of phosphorous acid
are phosphites, of phosphoric acid, phosphates, etc.