- Compound composed of two different
non-metallic elements.
STEPS IN NAMING BINARY
MOLECULAR COVALENT
COMPOUND
1. The more electronegative non-metallic
element is written or named last. This is
usually the element present on the right side
of the periodic table.
2. Greek prefixes are used to identify the number
of atoms per element present. If the first
element consists of only one atom, the
numerical prefix mono- is usually omitted.
GREEK NUMERICAL PREFIXES
1
2
3
4
5
monoditritetrapenta-
6
7
8
9
10
hexaheptaoctanonadeca-
3. For the second element, the stem name is
retained and the suffix –ide is added to
the it.
+6 -2
S O
2
6
S O
3
Sulfur trioxide
CO2
Carbon dioxide
CCl4
Carbon tetrachloride
N2O
Dinitrogen monoxide
N2O4
Dinitrogen tetroxide
P2O5
Diphosphorus pentoxide
EXCEPTIONS TO THE RULE
H2O
- water
NH3 - ammonia
PH3
- phosphine
CH4
- methane
- contains polyatomic (more than one type of
atom) ions
- Naming follows the same step as binary
ionic compounds, except that the name of
the metal (using Roman numeral if
necessary) is named or written first followed
by the name of the polyatomic ion
NAMES AND CHARGES OF SOME COMMON POLYATOMIC IONS
CHARGES
CHARGES
CaCO3
calcium carbonate
KNO3
potassium nitrate
Cu(OH)2
copper (II) hydroxide
Cu(OH)3
copper (III) hydroxide
HgNO3
mercury (I) nitrate
(NH4)2SO4
ammonium sulfate
Non-metallic elements combined
with oxygen to form non-metallic
oxide. The non-metallic oxide reacts
with water to form an acid.
NM + O2 = NMO
NMO + H2O  ACID
TWO TYPES OF ACIDS
BINARY ACIDS – compounds of hydrogen
plus non-metal.
1. Add hydro- to the name of the NM.
2. Remove –ide and replace with –ic acid.
Ex. HF – hydrogen fluoride (binary
compound)
Hydrofluoric acid
HCl – hydrogen chloride
Hydrochloric acid
OXYACID – contains hydrogen,
oxygen and another element.
1. Polyatomic ion ends in –ate, replace –
ate with –ic acid.
Ex. H2SO4 – hydrogen sulfate
sulfuric acid
2. Polyatomic ion ends in –ite, replace –
ite with –ous acid.
Ex. H2SO3 – hydrogen sulfite
sulfurous acid
Metallic elements combined with
oxygen to form metallic oxide. The
metallic oxide reacts with water to
form a base.
M + O2 = MO
MO + H2O  BASE
BASE – identified by the presence of
the hydroxide (–OH) group
Write the name of the metal followed by
the word hydroxide.
Ex. NaOH – sodium hydroxide
Al(OH)3 – aluminum hydroxide
Fe(OH)2 – iron (II) hydroxide
Fe(OH)3 – iron (III) hydroxide