REVIEW OF IONIC BONDING CONCEPTS
PROPERTIES;
1)
2)
3)
4)
5)
6)
7)
8)
9)
Electrons transferred from METAL to a NONMETAL.
Ionic substances do not form molecules.
Ionic substances exist as mobile aqueous ions OR in a crystal lattice solid.
Ionic substances conduct electricity in the liquid and aqueous phases only,
because the ions can move to carry a charge.l.
Ionic solids do not conduct because the ions are fixed in place.
There are no mobile electrons in ionic substances of any phase; the electrons
are stable in the shell (clouds) of the ions.
A salt is a substance that contains metal and nonmetal ions.
The charges of all the ions in a neutral salt equals zero.
A CRYSTAL LATTICE is a geometrically predictable arrangement of ions
in the solid state, it is:
a. Very organized (low entropy)
b. Brittle
c. Not conductive.
d. Very strong attractions (electrostatic) cause high boiling points and
high melting points, and extreme hardness.
e. The formula of an ionic substance is the empirical formula of the
crystal; it gives the mole ration of ions.
CONDUCTIVITY: charges carried by mobile particles in a particular direction.
Ions can carry charges in the liquid and aqueous states. Free mobile electrons can also
carry charges; however electrons are never mobile in ionic substances.
SKILL ONE, WRITING FORMULAS WHEN GIVEN THE ELEMENTS.
A) OBTAINING IONIC CHARGES FROM PERIODIC TABLE.
a. Group one is positive one in ionic state.
b. Group two is positive two in ionic state.
c. Group 16 is negative two (with exceptions).
d. Group 17 is negative one (with exceptions).
e. A Roman numeral gives the positive charge of a metal, EX Cu(II) means
the Cu is positive two.
B) Balance the dissociation reaction such that the charges cancel for a neutral salt.
a. EXAMPLE, find the formula and write the dissociation reaction for a
neutral ionic compound of Ca and I
STEP ONE; find the charges of each element on the periodic table following the rules
above.
It is negative one because it is in group 17.
CaIx  Ca+2 + x ICa is +2 because it is in group 2
STEP 2a, Use algebra to find the ratio of negative to positive ions
0=
+2
+
-1
CaIx  Ca+2 + x ISTEP 2b; solve algebra to find the ratio of negative to positive ions
0=
+2
+ 2(-1)
CaIx  Ca+2 + x ISTEP 3, THE NUMBER YOU SOLVED FOR BECOMES BOTH COEFFICIENT
AND SUBSCRIPT OF IODINE IN THE DISSOCIATION REACTION.
0=
+2
+ 2(-1)
CaI2  Ca+2 + 2IDISSOCIATION REACTION: When an ionic substance dissolves in water. During
dissolving, the ions that were fixed and immobile in the crystal escape the crystal as
mobile ions in an aqueous solution. Dissociations must balance for both mass (number of
atoms of each element) and charge. This occurs in salts that are soluble according to
reference table F.
MFC 11/8/05