#12 Use electron dot structures to
determine formulas of the ionic compounds
formed when:
a. potassium reacts with iodine
+1 + I-1
K
K + I
The formula is: KI
b. aluminum reacts with oxygen
The formula is: Al2O3
Al
+ O
-2
+3
Al
Al O
-2
O
Al+3 O
-2
O
O
#13 What is the formula of the ionic compound
composed of calcium and chloride anions?
Cl
Ca
Cl
Ca+2
Cl-1
You need
1 calcium
and 2
chlorines
+2
Ca
and
-1
Cl
Cl-1
Ca+2
Ca1Cl2
The final formula is CaCl
2
#14 How can you describe the
electrical charge of an ionic compound?
The total positive
charge exactly
balances
the
total
-1
I
negative charge
making the compound
Sr
electrically
neutral.
I-1
+2
(+2) + (-1) + (-1) = 0
#15 What properties characterize
ionic compounds?
1.Ionic Compounds Often Have
High Melting and Boiling Points
The attraction between
cations and anions is
often very strong and
hard to break.
Cation
Anion
2. Ionic Compounds Form Crystals
3. Ionic Compounds are
hard and brittle when hit.
Metal: “sea of electrons”
Attract
Repel
4. Ionic Compounds Conduct Electricity
when dissolved in Water or Melted.
#16 define an ionic bond.
Ionic Bonding animation
Another NaCl animation
NaCl animation
An Ionic bond is when oppositely charged
ions form electrostatic bonds:
Example: NaCl
The Na+1 and the Cl-1 being oppositely
charged, attract each other.
#17 How can you represent the
composition of an ionic compound?
You write its chemical formula:
example Rb2S
NaCl
Fe2(SO4)2
#18 Write the correct chemical formula
for the compounds formed from each
pair of ions.
a. K+1 and S-2
K2S
b. Ca+2 and O-2
Ca2O2 CaO
c. Na+1 and O-2
Na2O
d. Al+3 and N-3
Al3N3 AlN
#19 Write the formulas for each compound:
a. barium chloride BaCl2
Ba+2 Cl-1
b. magnesium oxide MgO
Mg+2
O-2
c. lithium oxide
Li+1
Li2O
O-2
d. calcium fluoride
-1
+2
F
Ca
CaF2
# 20 Which pairs of elements are likely to
form ionic compounds?
a. Cl, Br
NO, they are both nonmetals!
b. Li, Cl
Yes, they will form LiCl
c. K, He
d. I, Na
NO, Helium doesn’t combine with anything!
Yes, they form NaI
#21 Describe the arrangement of sodium
ions and
chloride
ions in a
crystal of
sodium
chloride.
Empirical Formula: The smallest whole number
ratio of atoms in a compound--- NaCl
#22 Why do ionic compounds conduct electricity
when they are melted or dissolved in water?
Conductivity
salt dissolving
The ions are free to move around and thus they can
migrate to the opposite poles and exchange electrons.
http://www.chem.iastate.edu/group/Greenbowe/sections/projectfolder/flashfiles/thermoch
animations of coordination number
http://www.mhhe.com/physsci/chemistry/essentialchemistry/flash/flash.mhtml
Metallic Bond: "The SEA OF ELECTRONS"
Bonding by analogy of Dog bones