Ionic Bonds
Review!
• Ion – atom that is no longer neutral because it
has lost or gained electrons
 Now it has an electric charge!
• Atoms with 5, 6 or 7 valence e- become more
stable when that number increases to 8.
• Atoms with 1, 2 or 3 valence electrons can
become more stable when they lose electrons.
Lose e-  become positive ion
Gain e-  become negative ion
Ions and Their Charges
Ions and Their Charges
Name
Charge
Symbol or Fomula
Lithium
1+
Li+
Sodium
1+
Na+
Potassium
1+
K+
Ammonium
1+
NH4+
Calcium
2+
Ca2+
Magnesium
2+
Mg2+
Aluminum
3+
Al3+
Fluoride
1-
F-
Chloride
1-
CL-
Iodide
1-
I-
Bicarbonate
1-
HCO3-
Nitrate
1-
NO3-
Oxide
2-
O2-
Fsulfide
2-
S2-
Carbonate
2-
CO32-
Sulfate
2-
SO42-
Phosphate
3-
PO43-
What does this chart mean?!
• How does Li have a +1
charge?
• How does Aluminum have
a +3 charge?
• Notice how the names of
F, Cl, and I have changed?
Why?
Polyatomic Ions
• Polyatomic Ions – Ions that are made of
more than one atom.
– Ammonium
– Bicarbonate
• Group of atoms that reacts as a unit
– Have overall positive or negative charge
Ionic Bonds
• The attraction
between two oppositely
charged ions
– Form as a result of
positive and negative
ions being attracted to
each other.
• Form ionic compounds!
• Usually form between a
metal and nonmetal!
• When ionic compounds form, ions bond
in a way that balances out the charges
on the ions.
• The chemical formula for the compound
reflects this balance.
– combination of symbols that shows the
ratio of elements in a compound
Formulas of Ionic Compounds
Subscript - tells you the ratio of
elements in the compound
• if no subscript – it’s understood to be 1
Naming Ionic Compounds
• The name of the (+) ion comes first,
followed by the name of the (-) ion.
– Positive ion is usually a metal.
• If the negative ion is a single element,
end of it’s name changes to –ide.
• NaCl  Sodium Chloride
• MgO  Magnesium Oxide
• If the negative ion is polyatomic:
– Ends with -ate or -ite
• NH4NO3 ammonium nitrate (fertilizer)
Ionic Crystals
• Form solids by building up repeating
patterns of ions.
– Have orderly, three dimensional
arrangement called a crystal.
– Every ion is attracted to ions of opposite
charge that surround it.
– Many crystals are hard and brittle, due to
the strength of their ionic bonds
High Melting Points
• When ions have enough energy to
overcome the attractive forces between
them, they break away from each other.
– Crystal melts into liquid
– A lot of energy is needed to break these
bonds
Electrical Conductivity
• When ionic crystals
dissolve in water,
the bonds between
ions are broken.
• Ions are free to
move about & the
solution conducts
current.
• Solids do not
conduct current
well  good
insulators