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EQ: What are the guidelines to write and name Ionic formulas?. Ionic Bonding Day 2. Writing Ionic Formulas. Binary compounds are made up of two elements. Binary ionic compound are made up of a metal and a nonmetal. Writing ionic formulas. Ex: potassium chloride - PowerPoint PPT Presentation
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Ionic Bonding Day 2
EQ: What are the guidelines to write and name Ionic formulas?
Writing Ionic Formulas• Binary compounds are made up of two
elements.• Binary ionic compound are made up of
a metal and a nonmetal.
Writing ionic formulasEx: potassium chloride1. Write symbols for both
ions including charges2. Check to see if charges
balance
K+ Cl-
Balanced!
Formula is: KCl
Writing ionic formulasEx: calcium bromide1. Write symbols for both
ions2. Check to see if charges
balance3. If not balanced use
subscripts to balance charges
Ca2+
Formula is: CaBr2
Br-
Not balanced!
1(2+) + 2(1-) = 0
Writing Ionic FormulasEx: calcium sulfide1. Write Symbols2. Crisscross3. Check to see if
subscripts can be reduced
Ca2+ S2-
Formula is: Ca2S2
Reduce!!
Formula is: CaS
Correct!!
Predicting Ionic Charges• Groups 3-12:Many transition elements have more than
one chargeIron(II) = Fe2+ Iron(III) = Fe3+
If an element forms more than one ion, a Roman numeral is used to indicate the charge
Predicting Ionic Charges• Groups 3-12:Some transition elements have only one
oxidation stateZinc = Zn2+ Silver = Ag+
No Roman numeral is used for elements that have only one oxidation state
Writing Ionic FormulasEx: Iron(III) Oxide1. Write all symbols2. Check to see if charges
balance3. Use subscripts to
balance
Fe3+ O2-
Not balanced!
Formula is: Fe2O3
2(3+) + 3(2-) = 0
Writing Ionic FormulasEx: Iron(III) oxide• Another method for
writing balanced formulas is the crisscross method
• First write symbols• Charge of one ion is used
as subscript for other ion
Fe3+ O2-
Fe2O3
Writing ionic formulasRemember the Steps
• Write symbols• Crisscross• Reduce if needed
You Practice
Sodium iodideTin(IV) chloridePotassium sulfideCalcium iodide
Polyatomic ions• Polyatomic ions are tightly bound groups
of atoms that behave as a unit and carry a charge.
• For instance the sulfate anion, SO42-,is
made up of one sulfur atom and four oxygen atoms and has a 2- charge.
• You will need a list of polyatomic ions to determine the name and formula
Writing ionic formulas• Ionic compounds that contain a
polyatomic ion are called ternary ionic compounds
• The names usually end in ate or ite and you need to remember to look up the formula of the polyatomic ion
Writing ionic formulasEx: calcium nitrate• Write symbols• Crisscross to balance• If the polyatomic ion
requires a subscript, place parentheses around the ion
Ca2+ NO3-
Ca (NO3)
2
Writing ionic formulasEx: lithium carbonate• Write symbols• Crisscross and write
formula using parentheses if needed
• Notice that no parentheses are needed if only one polyatomic ion
Li+ CO32-
Li2CO3
Writing ionic formulasEx: magnesium hydroxide
• Remember that the hydroxide ion also needs parentheses
Mg2+ OH-
Mg(OH)2
Writing Ionic FormulasRemember the Steps
• Write symbols• Crisscross• Use parentheses if
needed• Reduce subscripts if
needed
You Practice!
ammonium sulfitecalcium phosphatemagnesium carbonate
Naming Ionic CompoundsEx: NaI
• Name the first ion• Name the second ion• Remember that negative
ions end in ide
The name of the compound is:sodium iodide
Naming Ionic CompoundsEx: CuO• Name the first ion• Recall that the copper ion
can be either Cu+ or Cu2+ • Since O has a 2- charge
is must be Cu2+ or Copper(II)
• Name the second ion
The name of the compound is:
copper(II) oxide
Naming Ionic CompoundsRemember the Steps• Name the first ion• Check to see if it needs a
roman numeral• Name the second ion
You Practice!!
ZnSKClCuBr2FeS
Naming Ionic CompoundsEx: K2Cr2O7
• If a formula contains three or more elements, it contains a polyatomic ion
• You must look up the name
• Cr2O72- is the
permanganate ion
The name of the compound is:
potassium permanganate
Naming Ionic CompoundsRemember the Steps• Name the first and
second ions• Remember to check if the
metal requires a roman numeral
• If it is a ternary compound look up the polyatomic ion
You practice!!
CaC2O4
Li2S04
Sn3(PO4)2