11/12/09
Ionic Naming
How to name Ionic Compounds
Cations Always First
•  Metals that are monatomic cations,
meaning there is only one atom acting
as a cation, keep their name and are
followed by the word “ion”
•  Group 1,2 and any metal that doesn’t
have multiple charges follow this rule
•  Metal
Be
Beryllium
Ion
Be+2
Beryllium ion
Cs
Cesium
Cs+1
Cesium ion
Al
Aluminum
Al+3
Aluminum ion
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Transition Metals
•  Since Transition metals are generally
less predictable than Group 1 and 2
metals, the Stock Naming system is
used.
•  Any metal that can form more than one
charge (yellow sheet) has to be named
using this system
•  Metal
Cu
Copper
Ion
Cu+2
Copper (II) ion
Cu
Copper
Cu+1
Copper (I) ion
The ion name is the element name
(charge in roman numerals) + ion
Anion second
•  All monatomic anions, elements that are
are not grouped that gain electrons, are
changed by using the stem on the name
and changing the ending to “ide” plus
the word ion.
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•  Non Metal
S
Sulfur
ion
S-2
sulfide ion
Br
Bromine
Br-1
Bromide ion
Polyatomic Ions
•  Polyatomic ions are groups of elements
that act as a single ion.
•  The names of polyatomics are listed on
your table.
•  Polyatomic name
Sulfate ion
Symbol
SO4-2
Chromate ion
CrO4-2
Nitrite ion
NO2-1
Ammonium ion**
NH4+1
*only positive polyatomic ion
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•  Notes to remember:
–  If the metal has more than one charge
possible (yellow) the element needs
Roman numerals
–  If the Anion is monatomic the ending is
changed to “ide”
–  If polyatomic, the name stays the same
–  Always end the name with the word “ion”
Writing Chemical
Formulas
•  Ionic compounds in order to become
stable each element forms 8 valence
electrons
•  To achieve stability, ionic compounds
also become neutral in over all charge
through the transferring of electrons
Page 4 bottom half
•  To combine Cs+1 and I-1, one electron is
transferred between the two elements.
•  The formula then becomes CsI
•  To combine Mg+2 and I-1, Mg+2 will give
up two electrons, meaning two I-1 will
need to accept the electrons.
•  The formula becomes MgI2
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•  If the number of electrons transferred is
the same, the numbers cancel out.
Example: Al+3 with N-3 becomes AlN not
Al3N3
Practice a few on the bottom of page 4
Criss Cross Method
•  Due to the charges balancing and
electrons transferring, a method known
as the criss cross method.
•  Turn to page 5 for examples.
Criss Cross notes
•  Always cross!
•  Put polyatomic groups in (parentheses)
–  (OH)-1 or (CO3)-2
•  If the charges crossed are the same or
“1”, do not write them.
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Naming from Formulas
•  Split the formula
•  Split after the cation (first element listed
unless ammonium (NH4)
•  Separate cation and anion
•  Find charges of each by reverse criss
cross
•  Name of compound= cation name
followed by anion name (no ion)
•  CaCO3
•  Fe2O3
•  KCl
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