Formula of ionic compounds

• Ionic compound

  Compound where the charges on the ions have to cancel out to leave an overall charge of zero
• Determining the formula of an ionic compound

  1. Identify the charges on the ions

  2. Ensure the charges cancel out to leave an overall charge of zero
• The formula of sodium chloride is NaCl
• The formula of sodium oxide is Na2O
• The formula of magnesium iodide is MgI2
• The formula of lithium carbonate is Li2CO3
• The formula of calcium hydroxide is Ca(OH)2
• The formula of magnesium nitrate is Mg(NO3)2
• example

  
• Basically do maths to find out the number, if the number is too small then add another one
• example two

  
• You put the brackets there are two hydroxide groups joined to one calcium atom.