SOL Review – May 1, 2013
Topic: Naming
Binary Molecular Compounds:
How to recognize: Covalent compounds consisting of 2 nonmetals
Prefixes:
Subscript
Prefix
1
Mono
2
Di
3
Tri
4
Tetra
5
Penta
6
Hexa
7
Hepta
8
Octa
9
Nona
10
Deca
Subscript: small number that comes after a chemical symbol
RULES:
1. The subscript tells you how atoms of that particular element are in the compound.
2. The prefix that goes IN FRONT OF the element’s name is based on how many atoms there
are of that element.
3. The name of the first element DOES NOT change, except by adding a prefix for how many
there are.
4. The name of the second element DOES change, by changing the ending to –ide and adding a
prefix.
5. Do not use the prefix mono- for the first element if there is only one atom of that element.
Examples:
1. Name: CO
-1 carbon, 1 oxygen
-carbon’s name does not change, do not add a prefix, since there is only one
-oxygen changes to oxide, since it’s the second element; prefix of mono- since there is one
oxygen
Answer: carbon monoxide
2. Name: CO2
-1 carbon, 2 oxygens
-carbon’s name doesn’t change, do not add a prefix
-oxygen changes to oxide, add a prefix of diAnswer: carbon dioxide
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3. Name: CCl4
-1 carbon, 4 chlorines
-carbon’s name doesn’t change, no prefix added
-chlorine changes to chloride, add the prefix of tetraAnswer: carbon tetrachloride
4. Name: Cl2O7
-2 chlorines, 7 oxygens
-chlorine’s name doesn’t change, add the prefix di-oxygen’s name changes to oxide, add the prefix heptaAnswer: dichlorine heptaoxide (or heptoxide)
Now go backwards! Write the formula from the name!
1. Write: phosphorus trichloride
-No prefix on phosphorus, so only 1 phosphorus atom
-Prefix on chloride is tri, which means 3; chloride comes from chlorine
Answer: PCl3
2. Write: dinitrogen tetraoxide (or tetroxide)
-Prefix on nitrogen is di, which means 2 nitrogens
-Prefix on oxide is tetra, which means 4; oxide comes from oxygen
Answer: N2O4
3. Write: tetraphosphorus decaoxide (or decoxide)
-Prefix on phosphorus is tetra, which means 4 phosphorus’s
-Prefix on oxide is deca, which means 10; oxide comes from oxygen
Answer: P4O10
Binary Ionic Compounds:
How to recognize: Ionic compounds consisting of a metal and a nonmetal (or cation and anion)
Writing formulas:
Criss-Cross method1. The charge on the metal crosses down to become the subscript on the nonmetal.
2. The charge on the nonmetal crosses down to become the subscript on the metal.
3. Drop the signs.
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Examples:
Na+1 Cl-1
Na1Cl1 = NaCl (don’t write 1’s)
Fe+3 O-2
Fe2O3
Pb+4 S-2
Pb2S4 = PbS2 (always reduce these subscripts!)
NAMING RULES:
1. The first element listed is the metal. The name of the metal does not change.
2. The second element listed is the nonmetal. The ending of the nonmetal changes to –ide
3. If the metal has more than one possible charge (the transition metals), use a Roman
Numeral to indicate which charge the metal has
Metals that ONLY have 1 possible charge:
Group 1 metals ALWAYS have a charge of +1
Group 2 metals ALWAYS have a charge of +2
Aluminum is ALWAYS +3
Cadmium is ALWAYS +2
Zinc is ALWAYS +2
Silver is ALWAYS +1
These metals do not get a Roman numeral after their name, because there’s only one possible
charge.
Examples:
1. NaBr
-Sodium is a group 1 metal, no Roman numeral needed
-Bromine changes to bromide
Answer: Sodium bromide
2. CaCl2
-Calcium is a group 2 metal, no Roman numeral needed
-Chlorine changes to chloride
Answer: Calcium chloride
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3. ZnO
-Zinc only has a possible charge of +2, no Roman numeral needed
-Oxygen changes to oxide
Answer: Zinc oxide
But what about the elements that have more than one possible charge??
The Roman numeral that goes AFTER the metal’s name refers to the CHARGE
For example: Cu+1 would be copper (I), because it has a charge of +1
Cu+2 would be copper (II), because it has a charge of +2
Examples:
1. Name: Fe2O3
-Criss-cross charges back up: Fe+3 O-2
-Fe+3 is iron (III); O-2 is oxide
Answer: Iron (III) oxide
2. Name: CrCl3
-Criss-cross charges back up: Cr+3 Cl-1
-Cr+3 is chromium (III); Cl-1 is chloride
Answer: Chromium (III) chloride
Go backwards! Write the formula from the name:
Examples:
1. Barium nitride
-Barium only has one possible charge, +2
-Nitride comes from nitrogen, which has a charge of +3
Ba+2 N-3…criss cross down… Ba3N2
2. Tin (IV) oxide
-Tin has a Roman numeral of (IV), charge of +4
-Oxide comes from oxygen, which has a charge of -2
Sn+4 O-2 …criss cross down… Sn2O4 … reduce: SnO2
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Naming with Polyatomic Ions!
How to recognize: These compounds have THREE or FOUR atoms in the formula!
Polyatomic Ions required to know:
Name
Formula
Carbonate
CO3-2
Sulfate
SO4-2
Nitrate
NO3-1
Hydroxide
OH-1
Phosphate
PO4-3
Ammonium
NH4+1
Naming ionic compounds follows the rules above, but DON’T CHANGE the name of the polyatomic
ion!
Examples:
1. Name: NaNO3
-Sodium only has one possible charge, +1
-NO3 has a charge of -1 to balance; NO3-1 is nitrate
Answer: Sodium nitrate
2. Name: (NH4)2S
-Criss-cross charges back up: NH4+1 S-2
-NH4+1 is ammonium; S-2 is sulfur, change ending to -ide
Answer: Ammonium sulfide
3. Name: Fe(OH)2
-Criss-cross charges back up: Fe+2 OH-1
-Fe+2 is iron (II); OH-1 is hydroxide
Answer: Iron (II) hydroxide
Go backwards!
Examples:
1. Write: Aluminum sulfate
-Aluminum is Al+3; Sulfate is SO4-2
-Criss-cross down
Answer: Al2(SO4)3
You MUST use parenthesis around the polyatomic ion if the subscript is greater than 1!!!
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2. Write: Tin (II) carbonate
-Tin (II) is Sn+2; carbonate is CO3-2
-Criss-cross down: Sn2(CO3)2
-REDUCE!
Answer: SnCO3
Naming Acids!
ALL ACIDS BEGIN WITH HYDROGEN!!!
Two types of acids: Binary and Ternary
RULES:
1. Name the acid like it’s an ionic compound
2. If the ending is –ide, change it to –ic and change hydrogen to hydro- at the beginning
3. If the ending is –ite, change it to –ous and drop hydrogen completely
4. If the ending is –ate, change it to –ic and drop hydrogen completely
5. Add the word acid to the end of the name
Examples:
1. HBr
-Ionic name: hydrogen bromide
-Ends in –ide, change to –ic
-Hydrogen becomes hydroAnswer: hydrobromic acid
2. HCN
-Ionic name: hydrogen cyanide
-Ends in –ide, change to –ic
-Hydrogen becomes hydroAnswer: Hydrocyanic acid
3. HNO2
-Ionic name: hydrogen nitrite
-Ends in –ite, change to –ous
-Hydrogen is dropped
Answer: nitrous acid
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4. H2CO3
-Ionic name: hydrogen carbonate
-Ends in –ate, change to –ic
-Hydrogen is dropped
Answer: carbonic acid
Go backwards!!
RULES:
1. If the acid name ends in –ic, it comes from either -ate or –ide
a. It comes from –ide if there is hydro- at the beginning
b. It comes from –ate if there is nothing at the beginning
2. If the acid name ends in –ous, it comes from –ite
Examples:
1. Write: hydrosulfuric acid
-Ends in –ic, starts with hydro-; comes from an –ide ending
-Original ionic name: hydrogen sulfide
-Hydrogen is H+1; sulfide is S-2
-Criss cross charges
Answer: H2S
2. Write: phosphorous acid
-Ends in –ous, nothing at the beginning; comes from an –ite ending
-Original ionic name: hydrogen phosphite
-Hydrogen: H+1; Phosphite: PO3-3
-Criss cross charges
Answer: H3PO3
3. Write: nitric acid
-Ends in –ic, nothing at the beginning; comes from an –ate ending
-Original ionic name: hydrogen nitrate
-Hydrogen: H+1; nitrate: NO3-1
-Criss cross charges
Answer: HNO3
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