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# Ionic compound with a multivalent metal

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```What does multivalent mean?
вЂў Some transition metals are multivalent
вЂў This means they have more than one ion
form
вЂў Look at the periodic table and locate some
multivalent transition metals
вЂў The most common ion is listed first
вЂў 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
вЂў We need to distinguish between the two or three
different ion forms
вЂў Use roman numerals from I вЂ“ VII which
corresponds to 1+ - 7+ ion charges
Metal Ion charge
1+
2+
3+
4+
5+
6+
7+
Roman Numeral
I
II
III
IV
V
VI
VII
вЂў For example:
вЂ“ Nickel can have two ion forms, Ni2+ and Ni3+
вЂ“ These are named nickel (II) and Nickel (III)
Writing formulas for compounds
containing a multivalent metal
вЂў There will only be 1 multivalent metal in a
compound
вЂў It is the metal so it is first in the name (same as
ionic compounds)
вЂў The roman numeral will indicate which ion form
is in the compound
Steps for writing formulas for
multivalent compounds
вЂў Step 1: Identify each ion and its charge
вЂў Step 2: Determine the total charges
needed to balance positive and negative
вЂў Step 3: Note the ratio of positive ions to
negative ions
вЂў Step 4: Use subscripts to write the
formula, 1вЂ™s are not shown in subscript
Try the formula for
titanium (IV) fluoride
ions
Total charge to balance
Ti4+ and F1+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
ions
Total charge to balance
3+
Mn
and
2S
+3+3 = -2-2-2
ratio
2:3
formula
Mn2S3
Writing formulas for compounds that
contain a multivalent metal
Key Points:
вЂў The metal is always first
вЂў The metal is always the positive ion
вЂў The metal could be a multivalent
metal
вЂў Go to the periodic table and check
Steps for Writing formulas for compounds
that contain a multivalent metal
вЂў
вЂў
вЂў
вЂў
вЂў
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
вЂў Step 6: Write the name using roman numerals in
brackets, following the positive ion to indicate
which ion was used
Example: FeI2
вЂў Is there a multivalent metal?
вЂў Yes, Fe, Iron
вЂў What are its different ion forms?
вЂў 3+ and 2+
вЂў What is the ratio of ions
вЂў 1 Fe : 2 I
вЂў What is the charge on the negative ion
вЂў I, Iodine, ion charge is 1вЂў but there are 2 so the total negative charge is
2вЂў Balance the positive and negative charges
вЂў Iron must have a 2+ charge to balance the two
1- charges from Iodine
вЂў Write the name using a roman numeral to say which ion form of Iron
is present
вЂў The negative ion must drop its ending and add
вЂ“ide (same as ionic compounds)
вЂў Iron (II) Iodide
Try another example: PbF4
вЂў
вЂў
вЂў
вЂў
вЂў
Pb
2+ and 4+
Pb 1: 4 F
FвЂ™s ion charge 1Balance the charges
вЂў 4+ charges to balance the 4 1- charges of F
вЂў Therefore Pb must be the 4+ ion
Meet out new class plant!
Video
Homework
compounds that contain a multivalent metal
вЂў 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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