1. Ionic Compounds
NaCl
Quartz

2. Many of the rocks and minerals on Earth are
made of cations and anions…ionic compounds.

3. The most common mineral on Earth is quartz, silicon dioxide, SiO2.
Most sand is
made of quartz.

4. The second most abundant compound
in Earth’s crust is aluminum oxide, Al2O3.
Corundum is the second hardest mineral known, and it is composed of aluminum oxide, Al2O3.
Pure corundum is clear.

5. Corundum is also one of the most valuable of the gem minerals.
Red corundum contains minute
amount of chromium
Blue corundum contains minute
amount of iron and titanium
Red corundum is called ruby.
Blue corundum is called sapphire.

6. Pyrite, or fool’s gold, is composed of iron sulfide, FeS2.

7. Although they are composed of ions, ionic compounds
are electrically neutral.
The total positive charge of the cations equals
the total negative charge of the anions.
Na+
Cl-
Ex: NaCl
(+1) +
(-1) =

8. Water is a molecular compound; it consists of molecules.
A glass of water would be filled with
millions of molecules of water.
H2O
H2O
H2O
H2O
H2O
H2O
H2O
H2O
H2O

9. Ionic compounds do not consists of molecules.
Ionic compounds do not exist as single discrete units,
but as collections of positively and negatively
charged ions arranged in repeating patterns.
Each ion is attracted to many oppositely charged ions.
In NaCl,
each Na+ is attracted to 6 Cl-,
and each Cl- is attracted to 6 Na+.

10. Properties of Ionic Compounds
Most ionic compounds are crystalline solids at room temperature.
The ions in such crystals are arranged in repeating
three-dimensional patterns.
NaCl
CsCl
ZnS

11.  Ionic compounds are very hard and brittle.
In an ionic compound, the ions are fixed in place and each ion forms ionic bonds with neighboring ions, resulting in a very strong structure.
It takes a lot of energy to break apart the ionic bonds holding these ions together. If we give a large crystal a hard enough whack with a hammer, the crystal will break in various places, the crystal shatters.

12.  Ionic compounds have high melting points.
In order to melt a substance, their particles must be able to move (flow).
In an ionic compound, the ions are fixed in place and each ion forms ionic bonds with neighboring ions, resulting in a very strong structure.

13.  Ionic compounds have high melting points.
In NaCl, each Na+ is ionically bonded to 6 Cl-,
and each Cl- is ionically bonded to 6 Na.
A large amount of energy is required to break all the ionic bonds holding these ions together. As a result, ionic compounds have high melting points.

14. Ionic compounds have high melting points.

15. Ionic compounds have high melting points.
Compound Name
Formula
Type of Compound
Melting Point °C
Boiling Point °C
Magnesium fluoride
MgF2
ionic
1261
2239
Sodium chloride
NaCl
801
1413
Sucrose (sugar)
C12H22O11
covalent
186
Water
H2O
100
Hydrogen fluoride HF
-83 20

16. Ionic compounds can conduct an electric current when melted or dissolve in water.
Charged particles must be free to move for a material to conduct an electric current. In the solid state, ionic compounds do not conduct electricity because their ions are fixed in place.
However, when ionic compounds are melted or dissolved in water, the ions are free to move.