Polyatomic Ions ­ Prefixes
The names of polyatomic ions can give you a clue about their formulas.
Many polyatomic ions end in "­ate", for example:
Nitrate ­
NO31­
Phosphate ­ PO43­
Carbonate ­ CO32­
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Polyatomic Ions ­ Prefixes
If the ending is changed to "­ite", the ionic charge stays the same, but
there will be one less oxygen in the ion. For example:
Nitrite ­
NO21­
Phosphite ­
PO33­
Carbonite ­
CO22­
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Polyatomic Ions ­ Prefixes
Prefixes "hypo­" and "per­" also can be added.
The prefix "hypo­" means there are two less oxygens than in the original ion.
For example:
Hyponitrite ­
NO1­
Hypophosphite ­ PO23­
Hypocarbonite ­ CO2­
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Polyatomic Ions ­ Prefixes
The prefix "per­" means there is one more oxygen than in the original ion.
For example:
Pernitrate ­
NO41­
Perphosphate ­
PO53­
Percarbonate ­
CO42­
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Polyatomic Ions ­ Prefixes
Write formulas for the following variations on the Chlorate ion:
Chlorate ­ Chlorite
­
Hypochlorite
­
Perchlorate
­
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ClO31­
Write the name and formula for compounds formed using the following:
Sodium and the phosphate ion
Calcium and the sulfate ion
Potassium and the chlorate ion
Aluminum and the hydroxide ion
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Write the name and formula for compounds formed using the following:
Beryllium and the nitrate ion
Magnesium and the bicarbonate ion
Nickel (II) and the carbonate ion
Nickel (III) and the carbonate ion
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Title: Jan 14­11:11 AM (8 of 25)
Title: Jan 14­11:21 AM (9 of 25)
Classify and Name the following compounds:
CuCO3
SnBr4
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S2O4
AgNO3
C2H6
Ca3P2
Acids
Acids are a combination of a positively charged hydrogen ion with a negatively charge ion, either a nonmetal or a polyatomic ion.
The combination is always dissolved in water; this is indicated using the subscript (aq), which stands for .
So, when you write the formula for an acid, you just add the subscript at the end. For example, the formula for Hydrochloric acid, which we used in previous demonstrations, is written as:
HCl(aq)
Title: Feb 12­6:47 PM (11 of 25)
Categories of Acids
We will be dividing acids into two categories:
1)
Non­oxyacids ­ Composed of hydrogen and a non­metal
(they may also include a polyatomic ion
which does not contain oxygen)
2)
Oxyacids­ Composed of hydrogen and a polyatomic
ion containing oxygen
The rules for naming each are slightly different.
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Non­Oxyacids
Balance the formula the same as you would with any ionic compound, using hydrogen as an ion with a 1+ ionic charge.
For example: Hydrogen combined with chlorine forms hydrochloric acid.
Determine the formula:
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Non­Oxyacids
What would the formula be for an acid composed of hydrogen and sulfur?
Hydrogen and nitrogen?
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Non­Oxyacids
What would the formula be for an acid composed of hydrogen and
the polyatomic ion cyanide?
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Naming Non Oxyacids
When naming non­oxyacids, follow these rules:
1)
Use the prfix "hydro­"
2)
Write the name of the negative ion, changing the ending to "­ic"
3)
Add the word "acid"
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Naming Non­Oxyacids
Name the acids we've previously looked at:
1)
HCl(aq)
2)
H2S(aq)
3)
H3N(aq)
4)
HCN(aq)
Title: Feb 12­6:47 PM (17 of 25)
Oxyacids
These are combinations of the hydrogen ion and a polyatomic ion containing oxygen.
Balance the ionic formula the same as normal, using hydrogen as a 1+ ion. Be sure to include the subscript (aq)
For example, how could you balance the formula for a combination of hydrogen and the nitrate ion?
H1+
Would end up being:
Title: Feb 12­6:47 PM (18 of 25)
and
NO31­
HNO3(aq)
Oxyacids
Balance the formula for an acid composed of hydrogen and the sulfate ion.
What is the formula for an acid including the chlorite ion?
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Naming Oxyacids
When naming oxyacids, the rules are a little different:
1)
Start with the name of the negative ion ...do NOT include the
"hydro­ " prefix
2)
Change the ending depending on the polyatomic ion used:
*if the ion ends in " ­ate", change the ending to " ­ic"
*if the ion ends in " ­ite", change the ending to " ­ous"
3)
Add the word "acid" to the end
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Naming Oxyacids
Just remember the rule: ate­ic, ite­ous
For example, name the oxyacids we looked at earlier:
HNO3(aq)
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Naming Oxyacids
H2SO4(aq)
HClO2(aq)
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Naming Oxyacids
This gives us groups of very similar sounding acids, all of which are different and have different chemical formulas. For example, we may have:
Hydronitric acid
Nitric acid
H3N(aq)
HNO3(aq)
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Nitrous acid
HNO2(aq)
Naming Acids
Write the name and formulas for acids formed by hydrogen and:
1)
Bromine
2)
Acetate
3)
Sulfite
4)
Phosphorous
5)
Carbonate
6)
Fluorine
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Homework
Complete the sheet on naming and writing formulas for acids.
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