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 di-

Answer: carbon dioxide

3. Name: CCl4

-1 carbon, 4 chlorines

-carbon’s name doesn’t change, no prefix added

-chlorine changes to chloride, add the prefix of tetra-

Answer: 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 hepta-

Answer: dichlorineheptaoxide (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: dinitrogentetraoxide (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: tetraphosphorusdecaoxide (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 method-

  1. 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.

Examples:

Na+1 Cl-1Na1Cl1 = NaCl (don’t write 1’s)

Fe+3 O-2Fe2O3

Pb+4 S-2Pb2S4 = 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

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

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!!!

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 hydro-

Answer: hydrobromic acid

2. HCN

-Ionic name: hydrogen cyanide

-Ends in –ide, change to –ic

-Hydrogen becomes hydro-

Answer: Hydrocyanic acid

3. HNO2

-Ionic name: hydrogen nitrite

-Ends in –ite, change to –ous

-Hydrogen is dropped

Answer: nitrous acid

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
  2. It comes from –ide if there is hydro- at the beginning
  3. It comes from –ate if there is nothing at the beginning
  4. 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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