IONS AND IONIC COMPOUNDS
• MONATOMIC IONS are atoms with a
positive or negative charge.
• Taking away an electron from an atom gives a
CATION with a positive charge
• Adding an electron to an atom gives an
ANION with a negative charge.
PREDICTING ION CHARGES
In general
• metals (Mg) lose electrons ---> cations
– Charge = group number
• nonmetals (F) gain electrons ---> anions
– Charge = group number -8
Charges on Common
Ions -4 -3 -2 -1
+1
+2
+3
By losing or gaining e-, atom has same
number of e-’s as nearest Group 8A atom.
METALS
M ---> n e- + Mn+
where n = periodic group
Na+
Mg2+
Al3+
sodium ion
magnesium ion
aluminum ion
Transition metals -->M2+or M3+ are common
Fe2+
iron(II) ion
Fe3+
iron(III) ion
See Table 9.2 page 255
Transition Elements
• Charges of 2+ and 3+ are common
• Roman numeral indicates the charge of the
ion
• Classical Name – suffixes indicate charge (sort of)
– ous means less
– ic means more
• See Table 9.2 page 255 
NONMETALS
NONMETAL + n e- ------> Xnwhere n = 8 - Group no.
Group 4A
Group 5A
Group 6A
Group 7A
C4-,carbide N3-, nitride O2-, oxide F-, fluoride
S2-, sulfide Cl-, chloride
Br-, bromide
I-, iodide
Predicting Charges on Monatomic Ions
POLYATOMIC
IONS
• Groups of atoms with a charge.
• Names end in –ite or –ate
– ite means less
– ate means more
MEMORIZE
page 257. 
the names and formulas in Table 9.3
Polyatomic Ions
HNO3
nitric acid
NO3nitrate ion
Polyatomic Ions
+
NH4
ammonium ion
One of the few
common
polyatomic
cations
Polyatomic
Ions
CO32carbonate ion
HCO3bicarbonate ion
hydrogen carbonate
Polyatomic
Ions
3-
PO4
phosphate ion
CH3CO2acetate ion
Polyatomic Ions
SO42sulfate ion
SO32sulfite ion
Naming Binary Ionic
Compounds
• Binary compounds are composed of
two elements, a metal and a nonmetal.
• Place the name of the cation first
and then the name of the anion.
– Remember the –ide suffix.
Sodium chloride
The cation
The anion
Writing formulas for
Binary Ionic Compounds
• Write the symbol of the cation and the
anion (include the charge)
• Add whatever subscripts are needed to
balance the charge
• Use the criss-cross method
– The charge of one ion becomes the subscript
of the other. Don’t forget to reduce to the
empirical formula.
Naming Ternary Ionic Compounds
• Ternary compounds are composed
of three or more elements.
• Place the name of the cation first
and then the name of the anion.
• Often end in –ite and -ate
Strontium sulfate
The cation
The polyatomic ion.
Don’t change the name
Writing formulas for
Ternary Ionic Compounds
• Write the symbol of the cation and the
anion (include the charge)
• Add whatever subscripts are needed to
balance the charge
• Use parentheses when the compound
contains more than one polyatomic ion
• Use the criss-cross method
Naming Binary Molecular
Compounds
• Binary compounds are composed of two
elements, two non-metals.
• The name identifies the elements and how
many of each atom there is in the compound.
• Name the elements in the order they appear in
the formula.
• Use prefixes to indicate the number of each
kind of atom.
• Omit mono- when the name has only one atom
of the first element.
• Use the suffix –ide for the name of the second
element.
9.3
Naming Binary Molecular
Compounds
Name these compounds!
•
•
•
•
•
•
•
•
PBr3
CrBr3
N2O
Na2O
Cl4
PbI4
P2O3
Fe2O3
Writing formulas for Binary
Molecular Compounds
• Use the prefixes in the name to
determine the subscript of each
element in the formula.
Phosphorus
pentafluoride
Naming Acids
1.
2.
3.
When the
name of
anion
name
the ends
anion
–ite,inthe
–ate,
the
–ide
acid
acid
, the
name
name is
is the
• Ionic
compounds
withinends
unique
properties
acidstem
the
stem
name
of the
ofbegins
anion
the anion
withwith
suffix
hydro-.
the–ic
suffix
The
followed
stem
–ous,ofby
followed
the
the word
• Contain
one
or more
atoms
anion
by
acid.
thehas
word
the
acid.
suffix
–ic andhydrogen
is followed by
the and
produce
word acid.H+ ions when dissolved in water
H2SO33 hydrogen sulfite
HNO
nitrate
HCl hydrogen chloride
Acid name – nitric
sulfurous
acidacid
acid name – hydrochloric acid
Naming Bases
• Ionic compounds with unique properties
• Produce OH- ions when dissolved in water
• Named the same as other ionic compounds
– Name of the cation followed by the anion.