Ch 7.1 Forming Ions
Review…
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Cations are Groups 1A, 2A, and 3A
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Anions are Groups 5A, 6A, and 7A
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They have positive charges.
They have negative charges
They end in “ide”
Majority of elements in Groups 4A and
8A do not usually form ions.
These are called monatomic ions!
Ions of Transition Metals
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Some transition metals in Groups 1B-8B
form more than one cation with
different charges.
Examples:
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Iron forms Fe2+ and Fe3+
Two methods of naming:
Stock System: Iron (II) ion and Iron (III) ion
 Classical name: Ferrous ion and Ferric ion
*We will use the stock system.
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Common Metal Ions with More
than One Ionic Charge
Symbol
Stock Name
Classical Name
Cu+
Copper(I) ion
Cuprous ion
Cu2+
Copper(II) ion
Cupric ion
Fe2+
Iron(II) ion
Ferrous ion
Fe3+
Iron(III) ion
Ferric ion
*Hg22+
Mercury(I) ion
Mercurous ion
Hg2+
Mercury(II) ion
Mercuric ion
Pb2+
Lead(II) ion
Plumbous ion
Pb4+
Lead(IV) ion
Plumbic ion
Common Metal Ions with More
than One Ionic Charge
Symbol
Stock Name
Classical Name
Sn2+
Tin(II) ion
Stannous ion
Sn4+
Tin(IV) ion
Stannic ion
Cr2+
Chromium(II) ion
Chromous ion
Cr3+
Chromium(III) ion
Chromic ion
Mn2+
Manganese(II) ion
Manganous ion
Mn3+
Manganese(III) ion
Manganic ion
Co2+
Cobalt(II) ion
Cobaltous ion
Co3+
Cobalt(III) ion
Cobaltic ion
Other Transition Metal Ions
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Some transition metals have only one
charge and do not use a Roman
numeral.
Examples (Write on your periodic table!)
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Silver: Ag+
Cadmium: Cd2+
Zinc: Zn2+
Polyatomic Ions
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The names of most polyatomic anions
end in “-ite” or “-ate”
The “-ite” ending indicates one less
oxygen atom than the “-ate” ending
Remember to use parentheses if more
than one is needed.
Write the formula that will form
between Ba and Cl
Solution:
1. Write the positive ion of metal
first, and then negative ion
Ba2+
Cl
2. Do the charges equal zero? NO!!
3. Use Criss-Cross method – write
subscripts
Ba2+
Cl1
BaCl2
Write the correct formula for the
compounds containing the
following ions:
1. Na+, S22. Al3+, Cl3. Mg2+, N34. Al3+, S2-
1. Na+, S2Na2S
2. Al3+, ClAlCl3
3. Mg2+, N3Mg3N2
4. Al3+, S2Al2S3
Binary Compound: is composed of
two elements and can be either ionic
or molecular.
Naming Binary Ionic Compounds
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To name a binary ionic compound,
place the cation name first,
followed by the anion name.
Remember the anion ends in “-ide”
Examples:
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Cs2O
NaBr
CuO
Cesium Oxide
Sodium Bromide
Copper(II) Oxide
Naming Compounds with
Polyatomic Ions
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State the cation first and then the
anion just as you did in naming
binary ionic compounds.
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KNO3
Potassium Nitrate
Mg(ClO2)2 Magnesium Chlorite
Naming Binary Molecular Compounds
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Binary molecular compound: must be composed of
two nonmetals
Use prefixes to indicate the number and kind of
atom in the compound
Use the following general format:
1st name: prefix + element name
2nd name: prefix + element name + “ide”
If there is only 1 of the 1st element, no prefix.
Prefixes in Covalent Compounds pg 228
Number of
atoms
Prefix
Number of
atoms
Prefix
1
mono-
6
hexa-
2
di-
7
hepta-
3
tri-
8
octa-
4
tetra-
9
nona-
5
penta-
10
deca-
Anyone want a cold glass
of dihydrogen monoxide?
Examples
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Name the following
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CO
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CO2
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N2O
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Carbon Monoxide
Carbon Dioxide
Dinitrogen Monoxide
Cl2O8
Dichlorine Octoxide
Writing Formulas for
Binary Molecular Compounds
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Use the prefixes in the name to tell
you the subscript of each element in
the formula.
Then write the correct symbols for the
two elements with the appropriate
subscripts.
The least electronegative element is
written first
Dinitrogen Tetroxide - N2O4
Examples
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Write formulas for the following:

Nitrogen Monoxide
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Carbon Tetrachloride
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NO
CCl4
Diphosphorous Pentoxide
P2O5
Naming Acids
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An acid is a compound that contains one
or more hydrogen atoms and produces
hydrogen ions (H+) when dissolved in
water.
All acids begin with hydrogen
General Format: HnX
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“X” represents a monatomic or polyatomic
anion.
“n” represents the number of hydrogen ions
3 Rules for Naming Common Acids
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If the name of “X” ends in -ate:
____________-ic acid
If the name of “X” ends in -ite:
____________-ous acid
If the name of “X” ends in -ide:
hydro-__________-ic acid
Name these acids
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H2SO4
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HCl
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H2S
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HNO3
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HClO2
Sulfuric Acid
Hydrochloric Acid
Hydrosulfuric Acid
Nitric Acid
Chlorous Acid
Writing Formulas for Acids
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If the acid ends in –ic, then “X” ends in –ate
If the acid ends in –ous, then “X” ends in –
ite
If the acid has hydro-______-ic, then “X”
ends in –ide.
The subscript on hydrogen is equal to the
charge of “X”.
Write the Formula
for the Following Acids
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Hydrobromic Acid
HBr
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Carbonic Acid
H2CO3
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Phosphoric Acid
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Sulfurous Acid
H3PO4
H2SO3
Homework
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7.1 pg 251 #14, 15(no g), 41