Thursday, 2 January 2014

Formulae of ionic compounds

Part 1: Know the charge

Remember the following of ions in the following groups:
Group      Charge
 I                     +1
 II                    +2
III                    +3

V                      -3
VI                     -2
VII                    -1

Memorize the charges of the following transition metals:

Element    Charge
iron           +2 or +3
silver             +1
copper      +1 or +2 (usually +2 for exam)
zinc                +2

Memorize the formulae of the following radicals:
nitrate            NO3-
sulfate            SO42-
carbonate      CO32-
hydroxide      OH-
ammonium    NH4+

Part 2: Formulae of ionic compound

E.g. 1 magnesium chloride

how to find formula of ionic compound from charges, magnesium chloride
Finding formula of magnesium chloride

E.g. 2 calcium nitrate

Finding formula of ionic compound calcium nitrate
Finding formula of calcium nitrate


  1. Hi Emily, your blog is amazing! Would like to check on the nitrate formula. Isn't nitrate NO3 with one negative charge instead of two?

    1. Hi Veraishere,
      Thanks for pointing that out! Yes, nitrate has a charge of negative 1. Changed it!


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