What are the charges fo ions formed
from elements of the following groups?
a) Group 1 1+
b) Group 2 2+
c) Group 16 2-
d) Group 17 1-
Draw the electron orbital diagrams for ions
of the following elements:
Magnesium - Cation
Oxygen - Anion
Bromine - Anion
Why do you think the unit cell
of LiF differs from that of the unit cell of LiCl?
The size of the ionic radii. The Chlorine ion is larger than
the Fluorine ion allowing more Lithium ions to bond with the
Chlorine ion.
Which of the following do you think
are ionic compounds?
| Compound |
Melting Point
(°C)
|
Boiling Point
(°C)
|
| Calcium Iodide |
784
|
1100
|
| Carbon Tetrachloride |
-23
|
77
|
| Hydrogen Fluoride |
-83
|
19.5
|
| Hydrogen Sulfide |
-85.5
|
-61
|
| Iodine Monochloride |
27
|
97
|
| Magnesium Fluoride |
1261
|
2239
|
| Methane |
-182
|
-164
|
Answer: Calcium Iodide and Magnesium Fluoride because Ionic
compounds generally have high melting and boiling points.
Which of the following do you think
are ionic compounds?
a) Motor Oil
b) Charcoal
c) Beeswax
d) Sodium Bromide
Answer: Sodium Bromide. Ionic compounds are generally hard
and brittle. Motor oil is a liquid thus it is neither. Charcoal
is Brittle but not hard. Beeswax is neither hard nor brittle.
What role does lattice energy play in
forming an ionic compound?
Answer: Lattice energy has such a large negative value that
it makes the overall reaction exothermic.
Forming an ionic compound is similar to a person standing
on the second rung of a ladder. The person can expend energy
by climbing to a higher step or potential energy can be expended
by slipping to a lower step.
In forming salt crystals there is a reaction between solid
sodium and chlorine gas.
Step 1 - Involves converting solid sodium to a gas which requires
an input of energy (like stepping to the 3rd rung of the ladder
from the 2nd rung)
Step 2 - Involves removing an electron from each sodium atom
which requires an input of energy (like stepping to the 5th
rung of the ladder from the 3rd)
Step 3 - Involves inputting energy to break the Cl2
atom into individual gaseous Cl atoms (like stepping to the
6th rung of the ladder from the 5th rung)
Step 4 - Involves adding the removed electron from the sodium
atom to the chlorine atom which gives off energy (like slipping
down to the 4th rung of the ladder from the 6th rung)
Step 5 - Involves the combining of the sodium and the chloride
ions into a crystal lattice which gives off much energy (like
slipping to the floor from the 4th rung of the ladder) On
the floor you are at a lower potential energy state than initially
and you have no lower to slip making you very stable like
an ionic compound. |
|
