Writing Chemical Formulas And Balancing Chemical Equations Webquest
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1
2Writing Chemical Formulas and Balancing Chemical
Equations Webquest
This activity goes with Chapter 9 in your textbook.
LET'S BEGIN.
Start by reading the following review of how to name compounds.
First let’s review how to name compounds.
REMEMBER, if it is ionic (metal + nonmetal), you write the name of the metal first and end the nonmetal with -ide. If you
are writing the formula then you have to make the cation and anion charges (also called oxidation numbers) equal zero.
For example, potassium sulfide contains the metal cation K with a charge of +1 and the nonmetal anion S with a charge
of -2. So we would need 2 +1 for every 1 -2 (+1+1-2=0). The formula would be K
S.
2
To figure out cation and anion charges look at the periodic table. Group 1 has a +1 charge, group 2 has a +2, group 13
(where Al is) has a +3, skip group 14 because they don't form ions, group 15 has a -3 charge, group 16 has a -2 charge,
group 17 has a -1 charge, and group 18 doesn't react.
periodic
1 or alkali
2 or alkaline
13
or
14
or
15
or
16
or
17
or
18
or
table group
metals
earth metals
Aluminum
Carbon
Nitrogen
Oxygen
Halogens
Noble
Family
Family
Family
Gases
charge
+1
+2
+3
Don't form
-3
-2
-1
Don't
ions
react
Transition metal (the short columns in the middle of the table) charges are given to you in the form of Roman numerals.
(I) =+1, (II) = +2, (III) = +3, (IV) = +4.
Polyatomic ions are compounds that have a charge. You have your polyatomic cheat sheet to use whenever you need
them.
polyatomic ion formula charge
carbonate
CO
-2
3
sulfate
SO
-2
4
ammonium
NH
+1
4
nitrate
NO
-3
For covalent compounds (nonmetal + nonmetal) you use prefixes to name the compound. The prefix stands for how
many of that atom there are in the compound. You must know the prefixes for the test. For example, carbon dioxide
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