Tuesday, March 20, 2012

CHEMICAL FORMULAS - NOMENCLATURE

 



Systematic chemical names of inorganic compounds were developed by a group of scientists who were part of the International Union of Pure and Applied Chemistry (IUPAC) which first met in 1921. Elements are represented by symbols which are the first, first two, or first and third letters from the name of the element. There are some notable exceptions, where the symbols
appears to have no connection to the name of the element. These symbols are derived from early names for these elements. The table below illustrates some of these. Systematic chemical names of inorganic compounds were developed by a group of scientists
who were part of the International Union of Pure and Applied Chemistry (IUPAC) which first met in 1921. Elements are represented by symbols which are the first, first two, or first and third letters from the name of the element. There are some notable exceptions, where the symbols appears to have no connection to the name of the element. These symbols are derived from early names for these elements. The table below illustrates some of these.
Present Name         Symbol                     Former Name
Antimony                Sb                            Stibium
Copper                    Cu                            Cuprum
Gold                        Au                            Aurum
Iron                         Fe                             Ferrum
Lead                       Pb                              Plumbum
Potassium              K                                Kalium
Silver                    Ag                               Argentum
Sodium                 Na                                Natrium
Tin                       Sn                                 Stanum
Tungsten             W                                  Wolfram
 

The names of inorganic compounds are constructed so that every compound can be named from its formula and each formula has a name unique to that formula. For the purpose of clarity, we will divide the formulas into the following categories:
1) Binary compounds of nonmetals (covalent molecules)
2) Binary compounds of a metal and nonmetal (ionic compounds)
3) Ternary and higher compounds (polyatomic ions and acids)
     I. Binary Covalent Compounds: two nonmetals
 

1. Name first element, preceded by Greek prefix for number of atoms. If one, omit mono.
2. Name the second element, preceded by Greek prefix for number of atoms even if one.
The ending of the second element is -ide.
Greek Prefixes: 
1 = mono             2 = di        3 = tri          4 = tetra                            5 = penta             6 = hexa    7 = hepta     8= octa                            9 = nona              10 = deca
 

Examples:         Formula                            Name
                              PCl3                        Phosphorous trichloride
                             SO2                         Sulfur dioxide
                             CO                           Carbon monoxide

No comments:

Post a Comment