CHEMISTRY PART 8 Ionic Compounds with Polyatomic Ions
Polyatomic Ions An ion made up of 2 or more different atoms. Covalent (non-ionic) bonds are between the atoms. The charge belongs to the entire ion. Names end in “ate” or “ite”. See the back of your periodic table.
Polyatomic Ions Examples: Ammonium (only one with a positive charge) NH 4 1+ The charge is for the entire compound. Phosphate PO 4 3- Phosphite PO 3 3-
Formula Writing Same process as before, but the polyatomic ion must be placed in brackets if it requires a subscript (more than one).
Formula Writing Example: Magnesium nitrate Mg 2+ NO 3 1- Mg(NO 3 )
Formula Writing Example: Iron (II) sulfate Fe 2+ SO 4 2- FeSO 4
Formula Writing Example: Ammonium sulfide NH 4 1+ and S 2- (NH 4 ) 2 S
Formula Writing Example: Iron (II) nitrate Pb 2+ and NO 3 1- Pb(NO 3 ) 2
Nomenclature 1. Write the name of the metal (cation) If it is a transition metal, follow those rules. 2. Write the name of the polyatomic ion.
Nomenclature Example: NaNo 3 Sodium nitrate Example: Ca(OH) 2 Calcium hydroxide
Nomenclature Example: Fe(OH) 3 Iron must have a 3+ charge Iron (III) hydroxide 1-
Nomenclature Example: CuSO 4 Copper must have a 2+ charge Copper (II) sulfate 2-
Nomenclature Example: (NH 4 ) 2 SO 4 Ammonium sulfate
Practice Worksheet Page 127 # 17, 18