Introduction to Naming Compounds

 In Chemistry, the term Nomenclature refers to a set of rules used to name compounds formed by the reaction of two or more elements.

Other sciences also use the word nomenclature to systematically define terms and facts pertaning to specific disciplines.

Genarally speaking, the positive element (ion) is always written first and the negative element (ion) is written next to it.

In ionic compounds the general rule is the following

Cation + Anion = Neutral Compound

  • Cation name remains the same in the element and the compound
  • Anion's name ending changes according to valence electrons (valences used in bonding)

Binary Compounds:

  • These are compunds that are made up of two elements
  • Binary Compounds always end in "IDE"


A compound of the  two elements Tin  and Chlorine can take everal different formulas and names

One compound that can be formed is SnCl2

Normally  we could call this compound tin chloride but we could be more specific and call it tin dichloride

Dichloride - meaning two chlorines ("di" form the latin word meaning "two")

There could be another compound between Tin and Chlorine with the formula SnCl4.  This compund is called tin tetrachloride.  Tetra in latin means "four".

Other forms of naming compound are:

  • Latin Form or Suffix Method

- not commonly used - here the name of cation changes as well as anion, a suffix is added after the cation:

  • "ous" for the lower oxidation state
  •  "ic" for the higher oxidation state

  SnCl2  --- Stannous chloride 

  SnCl4. --- Stannic Chloride

  • Roman Numeral Method - The Stock System

The Roman numeral indicates the charge on the transition metal

  SnCl2  --- Stannous chloride --- tin (II) chloride

  SnCl4. --- Stannic Chloride --- tin (IV) chloride


Name the following compounds:

  1. SO2
  2. SiI4
  3. SF6
  4. CS2


  1. SO2 is called sulfur dioxide
  2. SiI4 is called silicon tetraiodide
  3. SF6 is called sulfur hexafluoride
  4. CS2 is called carbon disulfide