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: Metal Ion charge 1+ 2+ 3+ 4+ 5+ 6+ 7+ – Nickel can have two ion forms, Ni 2+ Roman Numeral I II III IV V VI VII and Ni 3+ – These are named nickel (II) and Nickel (III)

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

ions Total charge to balance ratio formula

Ti

4+

and F

1 +4 = -1-1-1-1 1 : 4 TiF 4 189-191

Lowest Common Multiple-A useful Trick

Manganese (III) Sulfide Lowest common multiple for 3 and 2 is 6

ions

Mn

3+

and S

2 Total charge to balance ratio +3+3 = -2-2-2 2 : 3 formula Mn 2 S 3

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: FeI

2 • Is there a multivalent metal?

• What are its different ion forms?

• • What is the ratio of ions • • What is the charge on the negative ion • •

Yes, Fe, Iron 3+ and 2+ 1 Fe : 2 I I, Iodine, ion charge is 1-

• Balance the positive and negative charges • • Write the name using a roman numeral to say which ion form of Iron is present • •

but there are 2 so the total negative charge is 2 Iron must have a 2+ charge to balance the two 1- charges from Iodine The negative ion must drop its ending and add –ide (same as ionic compounds)

•

Iron (II) Iodide

Try another example: PbF

4

• Pb • 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

Meet out new class plant!

Video

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