WRITING FORMULA

• The primary function of chemical nomenclature is to ensure that a spoken or written chemical name leaves no ambiguity concerning which chemical compound the name refers to: each chemical name should refer to a single substance.
• Chemical compound formulas provide a shorthand communication for the structure of molecules and compounds.
• Reading and writing the chemical formula of compounds requires just a little understanding of the language of chemistry.
• The radical / polyatomic ions must be written in brackets, before the subscript is written.

  STEP 4
• Write down the symbols of the ions (cation and anion) involved.

  STEP 1
• Whenever applicable, write simple whole number ratio of the valences that give a net

  STEP 5
• Write the valency of each ion.

  STEP 2
• Interchange the valences of the ions and write as the subscript

  STEP 3
• POTASSIUM IODIDE – AN ADDITIVE OF TABLE SALT USED TO PREVENT GOITER
• MAGNESIUM OXIDE – USED AS AN ANTACID AND LAXATIVE
• SODIUM FLUORIDE – AN INGREDIENT USED IN TOOTHPASTE
• BARIUM OXIDE – USED IN CATHODE RAY TUBES, CROWN GLASS, AND CATALYSTS
• Covalent compounds - composed of 2 nonmetals
• When given a formula, first determine if it is an ionic or covalent compound.
• When covalent, name just like ionic compounds. The only difference is that you must add prefixes to state how many of each atom you have present.
• Fe2(CO3)3 


  iron(III) carbonate
• KCIO4 


  potassium perchlorate
• CCl4 


  carbon tetrachloride
• boron trifluoride

  BF3
• copper (II) sulfate 


  CuSO4
• sodium hydroxide 


  NaOH