 This powerpoint will guide you through learning to write the names for ionic compounds using the chemical formulas, and to write the chemical formulas if given the names. It is broken into six sections that match the sections on the associated handout  You do not need to write out this entire note, but instead use it to help you do the handout and jot short point form notes to remind you of key steps in the process.

Part 1: Writing names for simple ionic compounds

Chemical names always have two parts: one for each type of ion in it. To name an ionic compound: 1. Name the metal ion 2. Name the non-metal ion (BUT, end it in “ide”) 3. Write the name of the compound Ex: MgBr 2 is made from the metal magnesium and the non-metal bromine It gets named magnesium bromide

NameSymbol flourideF-F- chlorideCl - bromideBr - iodideI-I- oxideO 2- sulphideS 2- selenideSe 2- nitrideN 3- phosphidep 3- Table of common non-metal ion names

K2SK2S  Name: Potassium Sulphide  Ag 3 N  Name: Silver Nitride  CaI 2  Name: Calcium Iodide

Part 2: Writing formulas for simple ionic compounds

The chemical formula of an ionic compound contains symbols to identify each ion The chemical formula also shows the relative numbers of ions in the compound Ex: sodium chloride NaCl (one Na and one Cl) Ex: calcium flouride CaF 2 (one Ca, two F) Ex: aluminium oxide Al 2 O 3 (two Al, three O)

Positive and negative ions must balance out (be equal in number) The final formula must equal the smallest whole number ratio (remember math class?) Steps: 1. Identify the charge of each ion (+ or -) 2. Determine total charges needed to balance 3. Note the ratio of positive to negative ions 4. Use “subscripts” to write the formula (do not write the # 1)

 (from the periodic table: ) Zinc: Zn 2+ and Nitride N 3-  Zn 2+ : +2, +2, +2 = +6 N 3- : -3, -3 = -6  3 Zn 2+ ions needed for every 2 N 3- ions (3:2)  Zn 3 N 2

1. Aluminium is AL 3+ chloride is Cl - 2. Al 3+ : +3 = +3 Cl - : -1, -1, -1 = Al 3+ ions needed for every 3 Cl - ions (1 :3)  AlCl 3

Part 3: Writing formulas for multivalent compounds

 Sometimes an atom has more than one kind of ion it can become.  Ex. Iron (Fe) has two ion charges on its spot in the periodic table (3+ and 2+)  This means it can become Fe 3+ or Fe 2+

 The name for a multivalent compound tells you which ion charge is used  Ex. Iron (III) sulphide uses Fe 3+  Now figure out how many Fe 3+ it needs, and how many S 2- it needs (the charges have to balance out!!)  Fe 3+: = +6 S 2- : = - 6  This means I need two Fe 3+ and three S 2- Fe 2 S 3

 Chromium (II) chloride  Cr 2+ combines with Cl -  Cr 2+ :+2 = +2 (one chromium) Cl - : = -2 (two chlorine)  CrCl 2

Part 4: Writing names for multivalent compounds

 Ex. Cu 3 P  We know it will be Copper (something) phosphide, but what will the “something” be?  On the periodic table we can see Copper (Cu) can have the ion charge 2+ or 1+, So it could be Copper (I) or Copper (II)

 We know we have 3 coppers (from the formula Cu 3 P)  We know we have 1 phosphide  We also know the charges must be equal  One phosphide = 3-  We need to make 3+ with our copper.  If it is copper (I)= = 3+  It must be Copper (I) because there are 3 copper ions in the formula!  Name: Copper (I) phosphide

 What would be the name for MnO 2 ?  Mn can be: Mn 2+ or Mn 3+ or Mn 4+  O can only be: O 2-  You have 2 O: = 4- total charge  You have 1 Mn: it must be: 4+  Manganese (IV) oxide

Part 5: Writing names for polyatomic compounds

 A list of the common polyatomic ions is on page 92.  You need to know how to use this list, but you do not have to memorize it (you will be given it on tests)

 To be made of many ions (poly = many)  Ex: Ammonium have the chemical symbol NH 4 +  When it combines with Chlorine to make “Ammonium chloride” NH 4 Cl  This has three different elements in it (three is many!)

 What are the names for the following?  Ca(Ch 3 COO) 2  Name is: Calcium Acetate  Mg 3 (PO 4 ) 2  Name is: Magnesium Phosphate

Part 6: Writing formulas for polyatomic compounds

 Write the symbols for the Ions with their charges, Balance the total charges, Write the formula with the correct subscripts  EX: Ammonium Carbonate  Ammonium is NH 4 + Carbonate is CO 3 2-  NH 4 + : = 2+ CO 3 2- : - 2= 2-  2 NH 4 + for every one CO 3 2-  (NH 4 ) 2 CO 3

 What is the formula for iron (III) hydroxide?  Iron (III) = Fe 3+  Hydroxide = OH -  Fe 3+ : 3+ = 3+ OH - : = 3-  One iron = three hydroxides  Fe(OH) 3