Binary Compounds
Binary compounds contain only two elements.
All binary compounds end in -ide.
They are divided into two types, each of which
has different rules for how to name them and
write their formulas.
IONIC
= metal + nonmetal
COVALENT = nonmetal + nonmetal
Ionic Compounds
Metal + Nonmetal
Ionic compounds are held together by the
opposite charge of the metal (+) and the
nonmetal (-).
The SUM of the charges of all the atoms must
equal ZERO.
Ionic Examples
Na+1 and Cl-1 = NaCl sodium chloride
Na+1 and O-2 = Na2O sodium oxide
Ca+2 and O-2 = CaO
calcium oxide
Al+3 and Cl-1 =
AlCl3 aluminum chloride
Al+3 and O-2 =
Al2O3 aluminum oxide
Al+3 and N-3 =
AlN
aluminum nitride
Transition Metals
Transition metals can have different charges in
different compounds.
So … the name of the compound includes a
roman numeral that indicates the charge on the
transition metal.
EXAMPLES:
iron (II) chloride:
Fe+2 and Cl-1 = FeCl2
gold (I) sulfide:
Au+1 and S-2 = Au2S
Transition Metals - cont.
When you name a compound with a transition metal
you must determine the charge on the metal.
Remember … the sum of the charges of all atoms must
be zero. So use the charge on the nonmetal to figure
out the charge on the transition metal.
EXAMPLES:
CuF
Cu + (-1) =0
Cu=+1
Mn2O3
2Mn + 3(-2) = 0 Mn=+3 manganese(III) oxide
SnO2
Sn + 2(-2) = 0
Sn=+4
copper (I) fluoride
tin (IV) oxide
Covalent Compounds
Nonmetal + Nonmetal
Covalent compounds are held together by shared
pairs of electrons. No ions are involved.
Naming covalent compounds involves using a
prefix system that directly indicates the number of
atoms of each element in one molecule of the
compound .
Covalent Prefixes
1 = mono2 = di3 = tri4 = tetra5 = penta-
6 = hexa7 = hepta 8 = octa 9 = nona10 = deca-
NOTE:
Mono- is only used on the second element.
In front of “oxide”, drop the “a” or “o” at the end of the
prefix.
Covalent Examples
CO
CO2
PCl3
P2I4
N2O
S2F10
AsI2
B4C
=
=
=
=
=
=
=
=
carbon monoxide
carbon dioxide
phosphorus trichloride
diphosphorus tetraiodide
dinitrogen monoxide
disulfur decafluoride
arsenic diiodide
tetraboron monocarbide
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Polyatomic Ions
 Polayatomic ions are ions made from more
than one atom, and usually more than one
element. There is a single charge for the
entire ion.
 They are ions, and are named as ionic
compounds are.
 Parentheses are used when more than one of
a polyatomic ion is needed.
Examples of Polyatomic ions
ammonium
NH4+1
acetate
C2H3O2-1
nitrite
NO2-1
nitrate
NO3-1
sulfate
SO4-1
oxylate
C2O4-2
phosphate
PO4-3
hydroxide
OH-1
cyanide
CN-1
•Most polyatomic ions end in
“-ate” or “-ite”. This separates
them from binary compounds
that end in “-ide”.
•The positive polyatomic ion
ammonium ends in
“-ium”,
like many metals.
•Beware hydroxide and
cyanide, which break the
normal rules and end in “ide” but are polyatomic ions.
Polyatomic Ionic Examples
sodium acetate =
Na+1 and C2H3O2-1 = NaC2H3O2
calcium nitrite =
Ca+2 and NO2-1
= Ca(NO2)2
copper (II) phosphate =
Cu+2 and PO4-3
= Cu3(PO4)2
manganese (II) sulfate =
Mn+2 and SO4-2
aluminum cyanide =
Al+3 and CN-1
= Al(CN)3
ammonium sulfide =
NH4+1 and S-2
= (NH4)2S
= MnSO4
Acids
Aqueous acids have their own nomenclature,
based on their negative ion.
if ION ends in: then ACID is named:
-ate
-ic acid
-ite
-ous acid
-ide
hydro- & -ic acid
Acid Examples
HCl = hydrogen chloride -> hydrochloric acid
HNO3 = hydrogen nitrate -> nitric acid
HNO2 = hydrogen nitrite -> nitrous acid
H2PO4 (aq)
=
phosphoric acid
HI (aq)
=
hydroiodic acid
H2SO3 (aq)
=
sulfurous acid
H2C7H6O5 (aq)=
citric acid
HCN (aq)
hydrocyanic acid
=