Ions and Ionic Bonds
Charged particles (or ions) exert electrostatic
(or Coulomb) forces on each other. Oppositely charged ions
create attractive forces and these create ionic bonds.
Ionic bonds are electrostatic whether the ions are
atomic, like sodium Na+ and
fluoride F-, or polyatomic,
like ammonium NH4+
and sulfate SO4-2.
Ionic bonds lead to the formation of neutral compounds called salts.
Ionic bonds do not change the interacting ions in any major way,
so ions maintain their separate charges inside the salt, and are
usually discharged as ions when the salt breaks down. For example,
sodium sulfate, Na2SO4,
dissolves in water by releasing Na+
Lewis' theory helps us identify atoms that can easily
form ions. Ions that carry small charges and maintain inert
gas electron configurations should form most easily. These requirements
are met by the alkali cations (Li+,
alkaline earth dications (Mg+2,
and halide anions (F-,
Metals and non-metals nearly always form ionic compounds
when they combine. The metals lose electrons and the non-metals
gain electrons. Whenever you encounter a formula that combines metals
with non-metals, such as Na2O,
you should assume that the compound is ionic and you should assign
appropriate charges to each component (Na+
#1. Identify any atoms on the following list
that routinely exist as stable ions. What are the charges on these
ions? Mg, P, C, H, Cl, B, K, Na, Br
#2. Which of the following compounds are really
salts? Try to redraw these formulas to show their ionic components.