What does multivalent mean? Some transition metals are multivalent This means they have more than one ion form Look at the periodic table and locate some multivalent transition metals The most common ion is listed first What is the most common ion for Cu? , Au? Page 172

What are multivalent ions? For Example: Copper has 2 ion forms Can be a 1+ or 2+ ion Copper I Chloride Copper II Chloride

Writing names for multivalent ions We need to distinguish between the two or three different ion forms Use roman numerals from I – VII which corresponds to 1+ - 7+ ion charges For example: Nickel can have two ion forms, Ni2+ and Ni3+ These are named nickel (II) and Nickel (III) Metal Ion charge Roman Numeral 1+ I 2+ II 3+ III 4+ IV 5+ V 6+ VI 7+ VII

Writing formulas for compounds containing a multivalent metal There will only be 1 multivalent metal in a compound It is the metal so it is first in the name (same as ionic compounds) The roman numeral will indicate which ion form is in the compound

Steps for writing formulas for multivalent compounds Step 1: Identify each ion and its charge Step 2: Determine the total charges needed to balance positive and negative Step 3: Note the ratio of positive ions to negative ions Step 4: Use subscripts to write the formula, 1’s are not shown in subscript

Try the formula for titanium (IV) fluoride Ti4+ and F1- ions Total charge to balance +4 = -1-1-1-1 ratio 1 : 4 formula TiF4 189-191

Lowest Common Multiple-A useful Trick Manganese (III) Sulfide Lowest common multiple for 3 and 2 is 6 Mn3+ and S2- ions Total charge to balance +3+3 = -2-2-2 ratio 2 : 3 formula Mn2S3

Writing formulas for compounds that contain a multivalent metal Key Points: The metal is always first The metal is always the positive ion The metal could be a multivalent metal Go to the periodic table and check

Steps for Writing formulas for compounds that contain a multivalent metal Step 1: Identify a multivalent metal Step 2: identify its different ion forms Step 3: determine the ratio of ions in the formula Step 4: what is the charge on the negative ion? Step 5: Balance the positive and negative charges Step 6: Write the name using roman numerals in brackets, following the positive ion to indicate which ion was used

Example: FeI2 Yes, Fe, Iron 3+ and 2+ 1 Fe : 2 I Is there a multivalent metal? Yes, Fe, Iron What are its different ion forms? 3+ and 2+ What is the ratio of ions 1 Fe : 2 I What is the charge on the negative ion I, Iodine, ion charge is 1- but there are 2 so the total negative charge is 2- Balance the positive and negative charges Iron must have a 2+ charge to balance the two 1- charges from Iodine Write the name using a roman numeral to say which ion form of Iron is present The negative ion must drop its ending and add –ide (same as ionic compounds) Iron (II) Iodide

Try another example: PbF4 2+ and 4+ Pb 1: 4 F F’s ion charge 1- Balance the charges 4+ charges to balance the 4 1- charges of F Therefore Pb must be the 4+ ion Lead (IV) Fluoride

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Homework to help you practice writing formulas and naming compounds that contain a multivalent metal In workbook p. 68 1-3 Questions to practice writing formulas for ionic compounds Text book p. 188 1. a, c, e 2. b, d, f, h, j, l, n

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