Ionic Compounds:
Names and Formulas
SNC2D
Counting Ions
Sodium chloride or NaCl
contains 1 sodium ion and 1 chloride ion.
(Lewis dot diagrams)
Counting Ions
However, different ions may form compounds in
different ratios.
For example, calcium chloride or CaCl2
contains 1 calcium ion and 2 chloride ions.
(Subscripts are added to the symbols in a formula
if there is more than one of that type of atom.)
Counting Ions: Practice
FeCl3
Na2O
CaO
Fe2O3
NaClO3
Na2CO3
Ca(ClO3)2
Counting Ions: Practice
FeCl3 contains
Na2O
CaO
Fe2O3
NaClO3
Na2CO3
Ca(ClO3)2
1 iron ion and 3 chloride ions
Counting Ions: Practice
FeCl3 contains
1 iron ion and 3 chloride ions
Na2O contains
2 sodium ions and 1 oxide ion
CaO
Fe2O3
NaClO3
Na2CO3
Ca(ClO3)2
Counting Ions: Practice
FeCl3 contains
1 iron ion and 3 chloride ions
Na2O contains
2 sodium ions and 1 oxide ion
CaO contains
1 calcium ion and 1 oxide ion
Fe2O3
NaClO3
Na2CO3
Ca(ClO3)2
Counting Ions: Practice
FeCl3 contains
1 iron ion and 3 chloride ions
Na2O contains
2 sodium ions and 1 oxide ion
CaO contains
1 calcium ion and 1 oxide ion
Fe2O3 contains
2 iron ions and 3 oxide ions
NaClO3
Na2CO3
Ca(ClO3)2
Counting Ions: Practice
FeCl3 contains
1 iron ion and 3 chloride ions
Na2O contains
2 sodium ions and 1 oxide ion
CaO contains
1 calcium ion and 1 oxide ion
Fe2O3 contains
2 iron ions and 3 oxide ions
NaClO3 contains
1 sodium ion and 1 chlorate ion
Na2CO3
Ca(ClO3)2
Counting Ions: Practice
FeCl3 contains
1 iron ion and 3 chloride ions
Na2O contains
2 sodium ions and 1 oxide ion
CaO contains
1 calcium ion and 1 oxide ion
Fe2O3 contains
2 iron ions and 3 oxide ions
NaClO3 contains
1 sodium ion and 1 chlorate ion
Na2CO3 contains
2 sodium ions and 1 carbonate ion
Ca(ClO3)2
Counting Ions: Practice
FeCl3 contains
1 iron ion and 3 chloride ions
Na2O contains
2 sodium ions and 1 oxide ion
CaO contains
1 calcium ion and 1 oxide ion
Fe2O3 contains
2 iron ions and 3 oxide ions
NaClO3 contains
1 sodium ion and 1 chlorate ion
Na2CO3 contains
2 sodium ions and 1 carbonate ion
Ca(ClO3)2 contains 1 calcium ion and 2 chlorate ions
Why These Ratios?
It is the valence electrons that determine how
these ions combine.
For example, calcium had 2 valence electrons to
lose and each chlorine only wants 1. So calcium
has to find 2 chlorines.
Ratio Practice
Use diagrams to determine how the following
combine to form compounds:
Mg2+ and Br1Li1+ and P3Ca2+ and O2Al3+ and OH1K1+ and SO42-
Ratio Practice
Use diagrams to determine how the following
combine to form compounds:
Mg2+ and Br1MgBr2
Li1+ and P3Ca2+ and O2Al3+ and OH1K1+ and SO42-
Ratio Practice
Use diagrams to determine how the following
combine to form compounds:
Mg2+ and Br1MgBr2
Li1+ and P3Li3P
Ca2+ and O2Al3+ and OH1K1+ and SO42-
Ratio Practice
Use diagrams to determine how the following
combine to form compounds:
Mg2+ and Br1MgBr2
Li1+ and P3Li3P
Ca2+ and O2CaO
Al3+ and OH1K1+ and SO42-
Ratio Practice
Use diagrams to determine how the following
combine to form compounds:
Mg2+ and Br1MgBr2
Li1+ and P3Li3P
Ca2+ and O2CaO
Al3+ and OH1Al(OH)3
K1+ and SO42-
Ratio Practice
Use diagrams to determine how the following
combine to form compounds:
Mg2+ and Br1MgBr2
Li1+ and P3Li3P
Ca2+ and O2CaO
Al3+ and OH1Al(OH)3
K1+ and SO42K2SO4
Ratio Practice
Use diagrams to determine how the following
combine to form compounds:
Al3+ and O2Al2O3
Notice that the quick method of determining the
formula is to criss-cross the valences:
Criss-cross
But the ratio between the ions must be reduced to
lowest terms (and 1s are not written).
E.g. Pb4+ and O2- becomes
?
not
Pb2O4
Criss-cross
But the ratio between the ions must be reduced to
lowest terms (and 1s are not written).
E.g. Pb4+ and O2- becomes
PbO2
not
Pb2O4
Please complete “More Formula Practice.”
Ionic Compounds: Names
The name of an ionic compound is simply the
name of the positive ion followed by the name
of the negative ion, e.g.:
NaCl
CaCl2
Li2O
Ionic Compounds: Names
The name of an ionic compound is simply the
name of the positive ion followed by the name
of the negative ion, e.g.:
NaCl
CaCl2
Li2O
is
sodium chloride
Ionic Compounds: Names
The name of an ionic compound is simply the
name of the positive ion followed by the name
of the negative ion, e.g.:
NaCl
CaCl2
Li2O
is
is
sodium chloride
calcium chloride
Ionic Compounds: Names
The name of an ionic compound is simply the
name of the positive ion followed by the name
of the negative ion, e.g.:
NaCl
CaCl2
Li2O
is
is
is
sodium chloride
calcium chloride
lithium oxide
Ionic Compounds: Names
The name of an ionic compound is simply the
name of the positive ion followed by the name
of the negative ion, e.g.:
KOH
Mg(ClO3)2
NH4F
Ionic Compounds: Names
The name of an ionic compound is simply the
name of the positive ion followed by the name
of the negative ion, e.g.:
KOH
Mg(ClO3)2
NH4F
is
potassium hydroxide
Ionic Compounds: Names
The name of an ionic compound is simply the
name of the positive ion followed by the name
of the negative ion, e.g.:
KOH
Mg(ClO3)2
NH4F
is
is
potassium hydroxide
magnesium chlorate
Ionic Compounds: Names
The name of an ionic compound is simply the
name of the positive ion followed by the name
of the negative ion, e.g.:
KOH
Mg(ClO3)2
NH4F
is
is
is
potassium hydroxide
magnesium chlorate
ammonium fluoride
Names with Multivalent Ions
The only tricky ones to name are those that contain
multivalent ions. It is necessary to look at how
the ions have combined to figure out the valence
of the multivalent ion.
FeO
must be
Fe2O3
must be
Names with Multivalent Ions
The only tricky ones to name are those that contain
multivalent ions. It is necessary to look at how
the ions have combined to figure out the valence
of the multivalent ion.
FeO
Fe2O3
must be iron (II) oxide
(because oxide is O2-)
must be
Names with Multivalent Ions
The only tricky ones to name are those that contain
multivalent ions. It is necessary to look at how
the ions have combined to figure out the valence
of the multivalent ion.
FeO
Fe2O3
must be iron (II) oxide
(because oxide is O2- and the ratio is 1:1)
must be iron (III) oxide
Names with Multivalent Ions
Try it with copper:
CuCl2
CuSO4
Cu2O
Names with Multivalent Ions
Try it with copper:
CuCl2
CuSO4
Cu2O
copper (II) chloride
Names with Multivalent Ions
Try it with copper:
CuCl2
copper (II) chloride
CuSO4 copper (II) sulphate
Cu2O
Names with Multivalent Ions
Try it with copper:
CuCl2
copper (II) chloride
CuSO4 copper (II) sulphate
Cu2O
copper (I) oxide
More Practice
Please complete the
“More Practice”
handout and
textbook questions
p. 171 #6-8.