Chemistry Polyatomic Compounds

Groups of atoms that can be found as parts of a molecule. These atoms bond in such a way that they have a net electric charge (usually negative) Here are some of the most common polyatomics. The resulting group of atoms is an ion. So, it can form an ionic bond (usually with a metal) You do not need to memorize these!!!!

Polyatomic Compounds We will not be drawing the structures for these atoms at this time. However, we do need to be able to name them. 1.Write the name of the metal (including the roman numeral if necessary) 2. Write the name of the polyatomic Note: For a polyatomic, you do not need to change the ending of the molecule to - ide. Name the following Ca 3 (PO 4 ) 2 Calcium Phosphate CuSO 4 Copper (II) Sulphate BeCO 3 Beryllium Carbonate

Polyatomic Exception There is only one really common positive polyatomic ion, This polyatomic will form ionic compounds with non metals. To name these compounds, 1.Write the name of the polyatomic, 2.Write the name of the non metal changing the end to - ide NH 4 +  Ammonium NH 4 Cl Ammonium Chloride (NH 4 ) 2 O Ammonium Oxide

Multivalent/Polyatomic Chemical Formula Give the chemical formula for the following compounds Manganese (II) Sulphide Tin (IV) Fluoride Copper (II) Phosphate Ammonium Sulphate MnS SnF 4 Cu 3 (PO 4 ) 2 (NH 4 ) 2 SO 4

e.g. 1/ What is the chemical formula of sodium phosphate? Step 1 – Write the symbols of each ion, beginning with the cation (metal) Na PO 4 Step 2 – Write the ionic charge above each Na PO 4 Step 3 – Cross the charge to the oppose ions subscript Na PO 4 Step 4 – Re-write the formula. Make sure you put brackets around the polyatomic ion if it has gained a new subscript! = Na 3 PO 4 Try: Copper (II) Nitrate