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Chemistry Unit 6 Part 4

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Chemical Bonding: Polyatomic Ions. Polyatomic Ions. Writing Formulas / Naming Compounds ... for the following compounds. Lithium sulfate. Calcium acetate ... – PowerPoint PPT presentation

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Title: Chemistry Unit 6 Part 4


1
Chemistry Unit 6 Part 4
  • Chemical Bonding Polyatomic Ions

2
Polyatomic IonsWriting Formulas / Naming
Compounds
  • A polyatomic ion is a covalent molecule that has
    an ionic charge. (As opposed to being a neutral
    molecule.)
  • Poly many
  • Atomic atoms
  • Ion charged particle
  • A charged particle that consists of more than one
    atom.

3
Polyatomic Ions
  • Examples
  • Sulfide ? Sulfate SO4-2
  • Nitride ? Nitrate NO3-1
  • Phosphide ? Phosphate PO4-3
  • Chloride ? Chlorate ClO3-1
  • Carbonide ? Carbonate CO3-2
  • Notice the ending has changed to ate.

4
Polyatomic Ions
  • Examples
  • Sulfide ? Sulfite SO3-2
  • Nitride ? Nitrite NO2-1
  • Phosphide ? Phosphite PO3-3
  • Chloride ? Chlorite ClO2-1
  • Notice the ending has changed to ite.

5
Polyatomic ions
  • Not all polyatomic ions end in -ate or -ite.
  • Some other examples
  • Ammonium NH41
  • Hydroxide OH-1
  • Some Polyatomic ions contain more than two
    elements.
  • Ex. Acetate C2H3O2-1

6
Writing Formulas
  • Sodium Sulfate
  • Write the symbol for the metal. Add the
    oxidation number from the periodic table.
  • Na1
  • Write the formula for the polyatomic ion from the
    ion chart. Add its oxidation number.
  • SO4-2

7
Sodium SulfateNa 1 SO4-2
  • Determine the common factor of the two oxidation
    numbers. In this case, 2.
  • Decide how many of each ion is needed to equal
    the common factor. In this case, 2 sodium ions
    and 1 sulfate ion.
  • Write these numbers as the subscript for each
    ion.
  • Na2SO4

8
Calcium Phosphite
  • Write the symbol for the metal. Add the
    oxidation number from the periodic table.
  • Ca2
  • Write the formula for the polyatomic ion from the
    ion chart. Add its oxidation number.
  • PO3-3

9
Calcium PhosphateCa 2 PO4 -3
  • Determine the common factor of the two oxidation
    numbers. In this case, 6.
  • Decide how many of each ion is needed to equal
    the common factor. In this case, 3 calcium ions
    and 2 phosphate ions.
  • Write these numbers as the subscript for each
    ion.
  • Ca3(PO3)2
  • Notice that the polyatomic ion must be placed in
    parenthesis or, instead of 2 phosphate ions, you
    would have 32 Oxygen atoms and 1 Phosphorus
    atom. Ca3PO32

10
Naming Compoundsw/ Polyatomic Ions
  • KClO3
  • Write the name of the metal.
  • Potassium
  • Write the name of the polyatomic ion from the ion
    chart.
  • Chlorate
  • Name the compound.
  • Potassium Chlorate

11
Mg3(SO3)2
  • Name the metal.
  • Magnesium
  • Name the polyatomic ion from the ion chart.
  • Sulfite
  • Name the compound.
  • Magnesium Sulfite

12
An Additional Example
  • Calcium Hydroxide
  • Ca2 OH-1
  • The least common factor is 2. Therefore, 1
    calcium ion will bond with 2 hydroxide ions to
    form a neutral compound.
  • Ca(OH)2
  • If you omitted the parenthesis, you would not
    have 2 hydroxide ions. Instead you would have 2
    hydrogen atoms and one oxygen atom. CaOH2

13
Try these
  • Write names for the following compounds.
  • CaCO3
  • Al2(SO4)3
  • Ca(ClO2)2
  • K3PO4
  • Mg(OH)2

14
Answers
  • CaCO3 Calcium carbonate
  • Al2(SO4)3 Aluminum sulfite
  • Ca(ClO3)2 Calcium chlorate
  • K3PO4 Potassium phosphate
  • Mg(OH)2 Magnesium hydroxide

15
Now, these!
  • Write formulas for the following compounds.
  • Lithium sulfate
  • Calcium acetate
  • Aluminum nitrite
  • Magnesium phosphate
  • Sodium carbonate

16
Answers
  • Li2SO4 Lithium sulfate
  • Ca(C2H3O2)2 Calcium acetate
  • Al(NO2)3 Aluminum nitrite
  • Mg3(PO4)2 Magnesium phosphate
  • Na2CO3 Sodium carbonate
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