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WHETHER THERE IS ANY EASY WAY TO STUDY IUPAC NOMENCLATURE OF ORGANIC COMPOUNDS??
Atoms of the same or different elements can combine in set proportions to form compounds. The proportions are determined by the numbers of electrons shared or exchanged between elements.

This combining power of elements is most readily learned by memorizing each element's common charge or valence. You can think of valence as something similar to a connecting link for building blocks. Some atoms only can form one link with other atoms while others may form multiple links.

Naming Ionic Compounds

We can learn the nomenclature of common ionic inorganic compounds by memorizing the following tables of common ions.

Sometimes clusters of atoms are called groups and we learn a charge for the group as a whole. The order of the letters in a group should be maintained when writing the formula.

The elements and groups with positive charges (cations) are written and named first as in the case of LiF, lithium fluoride and NH4Cl, ammonium chloride.

Note that some metals have more than one common charge and we use a Roman Numeral to designate which ion is present in the compound such as iron(III)...read as iron 3. If a metal only has one common charge, the Roman Numeral is not used.

The anions that are formed from single atoms are named by dropping the elemental suffix and adding "-ide".

The overall charge of an ionic compound should be zero. When you combine atoms or groups to form a compound, the key is to make sure that the overall charges are balanced.

There is a clever way to arrive at the formula when you have elements or groups that have different charges. Use the charge of each element or group as the subscript for the other element or group as shown in the following animation.

Table of Cations

 +1 charge
    

+2 charge
    

+3 charge
    

+4 charge

H+                        hydrogen
    

Ca2+          calcium
    

Al3+                  aluminum
    

Si4+                  silicon

Li+                        lithium
    

Be2+               beryllium
    

Fe3+                     iron(III)
    

Sn4+                    tin(IV)

K+               potassium
    

Ba2+                 barium
    

 
    

Pb4+                 lead(IV)

Na+                     sodium
    

Cu2+                 copper(II)
    

 
    

 

Ag+                       silver
    

Fe2+                  iron(II)
    

 
    

 

Cu+                       copper(I)
    

Mg2+                     magnesium
    

 
    

 

NH4+                  ammonium
    

Zn2+                 zinc
    

 
    

 

 
    

Sn2+                   tin(II)
    

 
    

 

 
    

Hg2+                    mercury(II)
    

 
    

 

 
    

Ni2+                  nickel
    

 
    

 

 
    

Pb2+                 lead(II)
    

 
    

 

Table of Anions

-1 charge
    

-2 charge
    

-3 charge
    

-4 charge

F- fluoride
    

O2- oxide
    

PO43- phosphate
    

C4- carbide

Cl- chloride
    

S2- sulfide
    

P3- phosphide
    

 

Br- bromide
    

CO32- carbonate
    

N3- nitride
    

 

I- iodide
    

SO42- sulfate
    

 
    

 

OH- hydroxide
    

HPO42- hydrogen phosphate
    

 
    

 

CN- cyanide
    

 
    

 
    

 

HCO3- bicarbonate*
    

 
    

 
    

 

NO2- nitrite
    

 
    

 
    

 

NO3- nitrate
    

 
    

 
    

 

CH3CO2- acetate
    

 
    

 
    

 

H2PO4- dihydrogen phosphate
    

 
    

 
    

 

HSO4- hydrogen sulfate
    

 
    

 
    

 

* The name "bicarbonate" is actually a common name. It is given here because it is so commonly used. The proper chemical name for this group is "hydrogen carbonate". Sometimes it is hard to know what a substance is from the common name.

Examples of Ionic Inorganic Compounds
Try to figure out the name or formula and then click on the formula or name to see the correct answer.

Fe2O3

ammonium nitrate

MgCl2

sodium bicarbonate

CaCO3

mercury(II) sulfide

Naming Molecular Compounds

Most elements can be drawn by just using the symbols. However, the most stable form for many elements is a compound rather than the individual atom. The most common examples of these binary (2 atom) compounds are shown in the following table.
hydrogen     H2
nitrogen     N2
oxygen     O2
fluorine     F2
chlorine     Cl2
bromine     Br2
iodine     I2

The non-ionic inorganic compounds (molecular inorganic compounds) are similar to these compounds but are combinations of two or more nonmetallic elements. Most of these compounds are combinations of elements from Groups IVA to VIIA with one another or with hydrogen.

When a hydrogen atom forms compounds with the nonmetals, the hydrogen atom is named first and the nonmetal is named as if it were a negative ion.
HF (g)     hydrogen fluoride...The (g) for (gas state) must be shown since HF in a solution of water is called hydrofluoric acid. This is also done with HCl, HBr and HI. They are all in the same family.
H2S (g)     hydrogen sulfide...In a water solution this would be called hydrosulfuric acid.

The following compounds are exceptions to this rule...
H2O     water...It is not known as dihydrogen oxide.
NH3     ammonia...It is not known as trihydrogen nitride.
CH4     methane...The compounds composed of carbon have their own special names.

When other elements combine to form binary compounds, the formula is usually written by putting the elements in order of increasing group number.

    The number of atoms is given by a prefix, such as "mono", "di", "tri", "tetra", "penta", "hexa", "hepta" and "octa"...for 1, 2, 3, 4, 5, 6, 7 and 8.

    Always use the entire prefix except for monooxide...which is named monoxide.

    Never use the mono prefix for the first element and always use a prefix for the second element.

CO     carbon monoxide
NO     nitrogen monoxide
N2O     dinitrogen monoxide...laughing gas
PCl3     phosphorus trichloride
CCl4     carbon tetrachloride

Examples of Molecular Inorganic Compounds

Try to figure out the name or formula and then click on name or the formula to check your answer.

        SO2

        nitrogen dioxide

        HBr (g)

        sulfur trioxide

        HCl (g)

        carbon dioxide

Deciding Which Nomenclature Rules to Follow

1. Determine whether the compound is an ionic compound or a molecular compound.

    If a metal is present, the compound is an ionic compound for the purposes of this course. If no metal is present, the compound is a molecular compound.

    If the ammonium ion, NH4+ is present, the compound is ionic.

2. If the compound is ionic, use the names and charges given in the tables.

3. If the compound is a molecular compound, use the rules for naming binary molecular compounds.


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