2. 3.2 Names and Formulas of Ionic Compounds

3. 1. Name the metal ion 2. Name the non-metal ion by ending the element name with the suffix “ide” Eg. MgO.....Magnesium oxide  ExamplesAl 2 O 3 CaF 2 Aluminum oxideCalcium fluoride

4.  The positive charges have to balance the negative charges 1. Identify each ion and its charge e.g Zinc nitride Zn 2+ N 3- 2. Determine the total charge needed to balance positive with negative and note the ratio of positive ions to negative ions e.g. +2 +2 +2 = +6 and -3 + -3 = -6 so 3 Zn ions and 2 N ions

5.  OR use the cross over technique...the charge on the metal becomes the subscript on the non-metal (lose the +) and the charge on the non-metal becomes the charge on the metal (lose the -)...reduce if needed e.g. Zn 2+ N 3- 2+2+3-

6. 3. Use subscripts to write the formula. A “1” is not shown. e.g. Zn 3 N 2 Calcium sulphideMagnesium phosphide Ca 2+ S 2- Mg 2+ P 3- Ca 2 S 2 (reduce)Mg 3 P 2 CaS

8. 1. Identify each ion and its charge e.g. Iron (III) sulphideFe 3+ and S 2- 2. Determine the total charges needed to balance positive with negative and note the ratio of positive to negative ions e.g. +3 +3 = +6 and -2 + -2 + -2 =-6 so 2 Fe ions and 3 S ions

9. OR use the cross over technique e.g. Fe S 3. Use subscripts to write the formula e.g. Fe 2 S 3 Iron (II) chlorideLead (IV) oxide Fe 2+ Cl - Pb +4 O 2- FeCl 2 Pb 2 O 4 (reduce) PbO 2 3+ 2-

11. 1. Identify the metal e.g. MnO 2 2. Verify that it can form more than one kind of ion by checking the periodic table or a chart e.g. manganese can be 2+, 3+ or 4+ 3. Determine the ratio of the ions in the formula e.g. 1 manganese for every 2 oxygen 4. Note the charge of the negative ion from the periodic table e.g. charge on the oxygen is 2-

12. 5. The positive and negative charges must balance out. Determine what charge needs to be on the metal to balance out the non metal. e.g. manganese must have a charge of 4+ to balance out 2 oxides with 2- 6. Write the name of the compound with a Roman numeral e.g. Manganese (IV) oxide ExampleCu 3 PMnO Cu 2+ or 1+ Mn 2+ or 3+ or 4+ P 3- so Cu 1+ O 2- so Mn 2+ Copper (I) phosphideManganese (II) oxide

13. 1. Identify each ion and its charge e.g. ammonium carbonate NH 4 + and CO 3 2- 2. Determine the total charges needed to balance positive with negative and note the ratio of positive ions to negative ions e.g. +1 + 1 = +2 and -2 so 2 ammonium ions and 1 carbonate ions

14. OR use the cross over technique e.g. NH 4 1+ CO 3 2- 3. Use subscripts and brackets to write the formula. Omit brackets if only one ion is needed e.g. (NH 4 ) 2 CO 3 Eg. Iron (III) hydroxideAmmonium sulphate Fe 3+ OH - NH 4 + SO 4 2- Fe(OH) 3 (NH 4 ) 2 SO 4

16. 1. Count the elements, if there is more than two then you have a polyatomic group. Figure out which grouping is the polyatomic. e.g. Al 2 (SO 4 ) 3 aluminum (not a multivalent) and sulphate (polyatomic) 2. Metal still goes first and doesn’t change. 3. Non metal goes second. If it’s a polyatomic the ending does not change to “ide” like an element does. e.g. Aluminum sulphate Ex. Fe 3 (PO 4 ) 2 NaOH Iron (II) phosphateSodium hydroxide