Classification and Nomenclature

Chemical Nomenclature:

The most common system is the IUPAC (International Union of Pure and Applied Chemistry) and is is used to name:

• Ions 
• Ionic Compounds   
• Multivalent Ions 
• Hydrates 
• Molecular Compounds 
• Acids and Bases 

Chemical Names and Formulas for Ions: 

An ion is an atom or molecular that is electrically charged due to the loss or gain of one or more electrons. 

• The chemical formula for an ion is represented with the symbol of the element and a superscript denoting the ion charge: Zn^2+  or  Se^2-   
• The name for an ion depends on whether it is a metallic or non-metal ion. 
• For metallic ions: the metal's name + ion = Zinc Ions 
• For non-metallic ions: the non-metal's name + "ide" + ion = Selenide Ion  

Chemical Names and Formulas for Ionic Compounds: 

An ionic compound is a bond between a positively charged molecule (cation) and a negatively charged molecule (anion)

• The chemical formula for an ionic compound is represented with the symbol of the positive element first and then the negative element. Superscripts are used to denote the ratio of charges, neutralizing the compound: BaCl2
• The name for an ionic compound uses the same order as the chemical formula without the subscripts and an "ide" for the anion: BaCl2 = Barium Chloride or SrF2 = Strontium Fluoride

Chemical Names and Formulas for Multivalent Ions: 

An multivalent ion are any atoms or molecules that have more than one common charge. The top number listed on the periodic table is the more common charge. While the chemical formula of these ions is similar to those of ionic compounds, the naming is fairly different. To name multivalent ions, there are two systems:

• The IUPAC System uses roman numerals in parenthesis to show the charge: Iron (III) Oxide
• The Classical System uses the latin names of these multivalent elements and 
• the suffix "-ic" for the larger charge: Ferric Oxide (Fe2O3) 
• the suffix "ous" for the smaller charge: Ferrous Oxide (FeO)   
• These classical names include 
• Ferr - Iron (Fe) 
• Cupp - Copper (Cu)
• Mercur - Mercury (Hg)
• Stann - Tin (Sn)
• Aunn - Gold (Au)
• Plumb - Lead (Pb) 
• Wolf - Tungsten (W)  
• Argent - Silver (Ag)   

Chemical Names and Formulas for Hydrates:  

Hydrates are substances chemically combined with water in a definite ratio.  

• The chemical formula for a hydrate takes another chemical formula and attaches the ratio of hydrate to H2O : Chemical Formula x # of Water Molecules+ H2O
• Cu(SO4) x 5H2O
• The name for a hydrate takes the name of another chemical formula and attaches the ratio of hydrates (number of water molecules) to it: Chemical Formula + Prefix (Mono-, Di-, Tri-, Tetra-...)+ "hydrate." 
• Copper (II) Sulphate Pentahydrate   

Chemical Names and Formulas for Molecular Compounds:  

Molecular compounds are any compounds made of two or more anions. It is important to note that some of these anions are diatomic or polyatomic in a solitary state: 

• H2 (Hydrogen)
• O2 (Oxygen)
• F2 (Fluoride)
• Br2 (Bromide)
• I2 (Iodine)
• N2 (Nitrogen)
• Cl2 (Chlorine)

• S8 (Sulphur)
• P4  (Phosphorus)

• The chemical formula is identical to that of an ionic compound
• The name for a molecular compound uses prefixes to denote the ratio of molecules in the compound: 
• Uses the name of the first element (usually no prefix)
• The name of the second element (w/ a prefix) and ends in "-ide"
• NO = Nitrogen Monoxide 
• Hydrogen does not get a prefix 
• H2S = Hydrogen Sulphide  

Examples include: 

• N2O4 = Dinitrogen Tetraoxide 
• CS2 = Carbon Disulphide 
• P4O10 = Tetraphosphorus Decaoxide  

Prefixes to know include:  

• Mono - 1
• Di - 2
• Tri - 3
• Tetra - 4 
• Penta - 5 
• Hexa - 6
• Hepta - 7
• Octa - 8
• Nona - 9
• Deca - 10 

Important Names and Formulas of Molecular Compounds: 

• Water - H2O 
• Hydrogen Peroxide - H2O2  
• Ammonia - NH3 
• Glucose - C6H12O6   
• Sucrose - C12H22O11  
• Methane - CH4 
• Propane - C3H8 
• Octane - C8H18 
• Methanol - CH3OH  
• Ethanol - C2H5OH   

Chemical Names and Formulas for Acids and Bases:  

For acids, hydrogen is always present in the compound. It appears first in the chemical formal unless it is part of a polyatomic group. To name acids, two systems are used: 

• The IUPAC System uses the aqueous hydrogen compound: HCl(aq)  = Aqueous Hydrogen Chloride    
• The Classical System uses the suffix "-ic" and or the prefix "hydro-": Hydrochloric Acid  

For bases, hydroxide is present in the compound, typically following the cation: NaOH or Ba(OH)2 

The same rule applies for naming: Sodium Hydroxide or Barium Hydroxide

Important Names and Formulas of Molecular Compounds:  

• Hydrochloric Acid - HCl 
• Nitric Acid - HNO3 
• Sulphuric Acid - H2SO4 
• Phosphoric Acid - H3PO4 
• Acetic Acid - CH3COOH 
• Ammonia - NH3  

-Simon Sierra