Writing formulas for multivalent ionic compounds

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Writing formulas for multivalent ionic compounds

• Transition metals have the ability to form more
  than one cation
• Therefore, a roman numeral is placed in the name
  to signify the charge on the cation
• Example
• Iron (III) Chloride
• Write the formula?

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Writing formulas for mulitvalent ionic compounds

• Write formulas for the following
• Copper (I) Oxide
• Copper (II) Oxide
• Answers - Cu2O CuO

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Naming compounds with multivalent metals

• If the metal is in group B it requires a roman
  numeral in the name.
• You will have to deduce the roman numeral based
  on the formula.
• Example
• Name CoI2
• Answer - Cobalt (II) Iodide

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Naming compounds with multivalent metals

• Deducing the roman numeral
• Multiply the charge on the anion by the number of
  anions and then divide by the number of cations
  to get the roman numeral.
• Write the names for Fe2S3 SnO2
• Answers -
• Iron (III) Sulfide Tin (IV) Oxide

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• Take ten minutes and work on sections 5 and 6 on
  the back side of your worksheet.

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Polyatomic Ions

• A group of atoms that carry a charge
• Examples
• SO42- NO31-
• Names of polyatomic ions that contain oxygen will
  end in -ate or -ite
• -ite is one less oxygen then ate
• Example
• Sulfate is SO42- Sulfite is SO32-
• Chlorate is ClO31- Chlorite is ClO21-
• Other polyatomic ions
• NH41 Ammonium CN1- cyanide
• OH1- Hydroxide

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Writing formulas using polyatomic ions

• The polyatomic ion is treated as one unit.
• Balance the charges
• Place parenthesis around the polyatomic ion if
  there is more than one
• Example
• Write the formula for Iron (II) Nitrate
• Fe2 and NO31- combines to make
• Fe(NO3)2

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Naming using Polyatomic ions

• Name the metal than name the polyatomic ion. If
  you need a roman numeral include it.
• Treat the polyatomic ion as one unit (as if it
  were one atom)
• Example - Name CuSO4
• Copper (II) Sulfate

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Exceptions for roman numerals

• Silver, Cadmium and Zinc do not get roman
  numerals.
• Ag is always 1, Cadmium and Zinc are always 2
• Tin and Lead need roman numerals. They are
  multivalent (multiple oxidation states)

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Naming Acids

• Memorize
• HCl - Hydrochloric Acid
• H2SO4 - Sulfuric Acid
• HNO3- Nitric Acid
• H3PO4 - Phosphoric Acid
• Note - Acids give off H1 (Hydrogen ions) and
  bases give off OH1- ions
• What do you get when an acid and base combine?

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Check for understanding

• Name or write the formula for
• Potassium Sulfate
• Chromium (III) Cyanide
• Fe(ClO3)3
• CuCl
• Answers
• K2SO4 Cr(CN)3
• Iron (III) Chlorate
• Copper (I) Chloride

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• Now finish your worksheet and work on your
  homework.
• Get help
• Make sure and check your answers on-line. You
  will be writing formulas all year and doing math
  based on these formulas. You get the formula
  wrong you get the math wrong.