Ionic Compounds
SNC2D
Review: Terms to Know
• Valence
– The combining capacity of an element
• Valence shell
– The outer electron shell of an atom, the electrons
in this shell are called valence electrons
• Isoelectric with a noble gas
– The same number of electrons as a noble gas
Review: Anions
1Cl
Cl
• Easier to gain 1 electron than lose 7.
• Therefore the atom becomes an anion by gaining an electron.
• It becomes more stable by gaining an electron. It becomes iso-electric
with Ar.
Review: Cations
1+
Na
Na
• Easier to lose 1 electron than gain 7.
• Therefore the atom becomes a cation by losing an electron.
• It becomes more stable by losing an electron. It becomes iso-electric
with Ne.
• http://teachertube.com/viewVideo.php?vi
deo_id=67110
The Ionic Bond
• An ionic bond is when an electron from
one atom is given to another atom and
they are held together by strong
electrostatic forces
• Ionic compounds are formed when ions
form a compound
Electrostatic attraction
When a metal gives up one or more
electrons to a non-metal, the resulting
oppositely-charged ions will experience an
electrostatic attraction :
How Ionic Bonds Form
11+
1+
Na
Na
Cl
Cl
1-
Ionic bonds and compounds
This electrostatic attraction is called an
ionic bond .
The resulting compound is an ionic
compound.
Solutions
An ionic compound dissolved in water is
said to be aqueous (aq).
Solutions
These compounds dissolve in water
because one side of the water molecule
(H2) is positive and attracts the negative
ions and the other side is (O) is negative
and attracts the positive ions.
Solutions
Because the charged ions can move freely,
solutions of ionic compounds are good
conductors of electricity.
Activity
• The properties of Ionic Compounds
Activity
Formulas for Ionic Compounds
1.
Write symbols with the metal first (metal+nonmetal
or cation+anion)
2.
Write the combining capacity (valence or ion
charge) for each element over the symbol
3.
Use “ c r o s s o v e r ” m e t h o d and reduce
numbers to lowest ratio
3+
2-
Al 2S 3
2+
2-
Mg2S2

Mg S
Naming Ionic Compounds
• metal first (cation), non-metal second
(anion)
***no capitals on elements unless you are
starting a sentence***
• Change ending of anion to “ide”
• Examples:
magnesium + fluorine  magnesium fluoride
aluminum + sulphur  aluminum sulphide
Try These
1. Look at each of the following pairs of elements. Predict whether each pair
would form ionic bonds. Explain your reasoning. [K]
a) Mg, O b) Zn, Cl
c) C, F
2. Explain why two non-metallic elements are not likely to form ionic bonds. [K]
3. When each of these compounds dissolves in water, what ions are released
and in what ratio? [I]
a) NaF
b) Li3N
c) K2O
4. Element X has three electrons in its valence orbit.
Element Y has seven electrons in its valence orbit.
a) Classify each of these elements as metal or non-metal.
b) What is the chemical formula of the ionic compound formed by these elements
when they react together?
5. A penny and a dime inserted into a pickle and connected to an electric circuit
can generate enough electricity to power a small electric buzzer. Suggest
why a pickle is better for this activity than a raw cucumber. [A]
Multivalent Ions
• Some metals form more than one type
of ion – called multivalent ions
– E.g. Fe can be Fe2+ or Fe3+ and we use
roman numerals to tell them apart
– iron (II) or iron (III)
Formulas for
Multivalent Ions
• iron (II) + fluorine  iron (II) fluoride
2+
Fe
1-
F

FeF2
• iron (III) + fluorine  iron (III) fluoride
3+
Fe
1-
F

FeF3
Two Shades of Iron Activity
• Observe the two solutions of iron – record
your observations.
• Compare the colour of the solutions.
Questions:
1. Swirling the solution allows oxygen from the
atmosphere to enter the solution and react with the
chemicals in the solution. What evidence of a
chemical change did you observe? [K]
2. Suggest a possible explanation for the evidence you
observed. [C]
Homework
Try These
1. Name each of the following compounds: [K]
a) CaF 2
b) K2S
c) Al2O3
d) LiBr
e) Ca3P2
2. Determine the chemical formula for the ionic compound that forms when
each of these pairs of element react.[K]
3. Copy and complete the following table: [K]
Name
a)
iron (II) bromide
b)
manganese (IV) oxide
c)
copper (I) sulfide
d)
iron (II) nitride
e)
copper (II) oxide
Formula
f)
CaBr3
g)
Fe2O3
h)
SnS
i)
K3P