NOMENCLATURE
Chapter 2
Chemical Formulas
• Formula Unit:
• Identifies exact number of atoms in an ionic compound
• Molecular formula:
• Identifies exact number of atoms in a covalent molecule
• Empirical formula:
• Shows the simplest whole number ratio of atoms in a
compound
molecular
H2O
C6H12O6
empirical
H2O
CH2O
O3
O
N2H4
NH2
DIATOMIC ELEMENTS
Some elements do not like to be alone…
so they bond to themselves!
HOFBrINCl
Ionic Compounds
• consist of a combination of cations and anions
formed from a transfer of electrons
• the formula unit is always identical to the empirical formula
• the sum of the charges on the cation(s) and anion(s) in
each formula unit must equal zero
The ionic compound NaCl
NAMING BINARY IONIC COMPOUNDS
RULE 1
Metal – Nonmetal
1. Write the metal (positive ion) first
2. Change the ending of the second word to -ide
Rule 1 Examples
1. KBr
2. CaBr2
3. LiF
4. Li2O
5. MgO
6. BaS
7. K3P
8. Na3N
1.
2.
3.
4.
5.
6.
7.
8.
Potassium Bromide
Calcium Bromide
Lithium Fluoride
Lithium Oxide
Magnesium Oxide
Barium Sulfide
Potassium Phosphide
Sodium Nitride
NAMING COMPOUNDS WITH
POLYATOMICS
RULE 2
Polyatomic Ions
1. DO NOT CHANGE ANYTHING!
2. When you have NH4 and a single element, change
the second word to -ide
Rule 2 Examples
1.
2.
Ba(SO3)
3.
Na2(CO3)
Na(HCO3) 4.
(NH4)3(PO4) 5.
(NH4)(OH) 6.
1. Ba(SO4)
2.
3.
4.
5.
6.
Barium Sulfate
Barium Sulfite
Sodium Carbonate
Sodium Bicarbonate
Ammonium Phosphate
Ammonium Hydroxide
Formula of Ionic Compounds
2 x +3 = +6
Al3+
Al2O3
1 x +2 = +2
Ca2+
3 x -2 = -6
O2-
2 x -1 = -2
Ca Br2
1 x +2 = +2
1 x -2 = -2
Na2CO3
Na+
Br-
CO32-
NAMING COMPOUNDS WITH
TRANSITION METALS
RULE 3
Transition Metals
1. Can have more than one type of charge
2. Write the charge number in roman numerals
Rule 3 Examples
1. Cu2O
2. CuO
3. FeCl2
4. FeCl3
5. SnCl4
6. Mn2O3
7. PbS
1.
2.
3.
4.
5.
6.
7.
Copper (I) Oxide
Copper (II) Oxide
Iron (II) Chloride
Iron (III) Chloride
Tin (IV) Chloride
Manganese (III) Oxide
Lead (II) Sulfide
NAMING HYDRATES
• What is a hydrate?
• Hydrates are named:
Compound • Prefix-Hydrate
FeCl3 • 6H2O = Iron (III) Chloride Hexahydrate
Name to Formula – Criss Cross Rule
1. Lithium Fluoride
2. Sodium Sulfide
3. Aluminum Bromide
4. Iron (III) Oxide
5. Carbonic Acid
6. Calcium Carbonate
7. Magnesium Acetate
8. Copper (II) Sulfate Pentahydrate
9. Ammonium Sulfite
10. Barium Hypochlorite
Covalent Compounds
• Referred to as molecules
• Consists of nonmetals covalently bonded
• nonmetals or nonmetals + metalloids
• Least electronegative element is usually written first
NAMING COVALENT COMPOUNDS
RULE 4
Nonmetal – Nonmetal
USE PREFIXES!
1. Change the ending of the second word to -ide
2. No mono on the first word
3. Drop any double vowels
NO2
nitrogen dioxide
N2O
dinitrogen monoxide
TOXIC!
Laughing Gas
Prefixes
Number of Atoms
1
2
3
4
5
6
7
8
9
10
Prefixes
Rule 4 Examples
1. CO
2. CO2
3. SO2
4. SO3
5. N2H4
6. N2O3
7. PCl3
8. SiO2
9. P2O5
10. CS2
11. Al2O3
1. Carbon Monoxide
2. Carbon Dioxide
3. Sulfur Dioxide
4. Sulfur Trioxide
5. Dinitrogen Tetrahydride
6. Dinitrogen Trioxide
7. Phosphorus Trichloride
8. Silicon Dioxide
9. Diphosphorus Pentoxide
10. Carbon Disulfide
11. Aluminum Oxide
ACIDS
• a substance that yields hydrogen ions (H+)
when dissolved in water.
• example: hydrochloric acid refers to a water
solution of the molecular compound hydrogen
chloride, HCl
• Many polyatomic ions are produced by the
loss of hydrogen ions from oxyacids.
Acid Name:
sulfuric acid
nitric acid
phosphoric acid
Polyatomic Ion:
H2SO4
HNO3
H3PO4
sulfate
nitrate
SO24
phosphate
PO34
NO3
NAMING ACIDS
• Binary acids: consist of two elements,
usually hydrogen and a halogen
• “HX”
• Oxyacids: contain hydrogen and a
polyatomic ion (usually oxygen and a third
nonmetallic element)
• “HXO”
NAMING BASES
• Base: a substance that yields hydroxide ions
(OH-) when dissolved in water.
NaOH
sodium hydroxide
KOH
potassium hydroxide
Ba(OH)2
barium hydroxide