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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 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?
Writing formulas for mulitvalent ionic compounds • Write formulas for the following: • Copper (I) Oxide • Copper (II) Oxide Answers - Cu2O CuO
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
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
Take ten minutes and work on sections 5 and 6 on the back side of your worksheet.
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
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
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
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)
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?
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
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.