Transcript ionic bond - cloudfront.net

Ionic Bonds
08/29 & 08/30
Catalyst
• Complete the Chart
Objectives
• I can explain how electrons are
transferred in an ionic bond.
• I can explain that ionic compounds form
crystals.
• I can use the octet rule and the Criss
Cross rule to predict how ionic bonds will
form.
Think Box:
• Look at your chart above. Do metals
form anions or cations? Do
nonmetals form anions or cations?
• Answer: Metals form positive
cations. Nonmetals for negative
anions.
 An ionic bond is the electrostatic attraction between
oppositely charged ions. eg. Na+ and Cl-
 Ionic compounds form when electrons are
transferred from a metal cation to a non-metal
anion.
 An ionic compound is made up of a metal and a
non-metal.
Lithium + Hydrogen
Lithium Hydride
Sodium + Chlorine
Sodium Chloride
Aluminum + Oxygen
Aluminum Oxide
 Ionic compounds form a crystal lattice structure.
Silver + Bromine
Silver Bromide
Sodium + Chlorine
Sodium Chloride
Magnesium +
Tellurium
Magnesium
Telluride
 Even though ions have a charge, ionic
compounds are neutral overall.
Examples
Na+ + Cl− → NaCl
Li+ + H− → LiH
Ca2+ + F- → CaF2
Al3+ + O2- → Al2O3
 Ionic compound names: list the metal first,
then the nonmetal. Change the last
syllable of the nonmetal to –ide. If the
metal forms more than one cation
(transition metals) indicate the ion formed
with a roman numeral.
Examples
Na+ + Cl− → NaCl
Li+ + H− → LiH
Ca2+ + F- → CaF2
Al3+ + O2- → Al2O3
Ag2+ + O2- → AgO
Sodium Chloride
Lithium Hydride
Calcium Fluoride
Aluminum Oxide
Silver (II) Oxide
 If ionic compounds are really large collections of ions
in a crystal lattice structure, why do we write equations
and chemical formulas showing just a few ions?
Examples
Na+ + Cl− → NaCl
Li+ + H− → LiH
Ca2+ + F- → CaF2
Al3+ + O2- → Al2O3
 Compound formulas show the proportion of cations
to anions in an ionic compound.
 The proportion is based on an overall neutral
compound.
 Use the Kris-Cross rule to find the correct
proportion.
Kris Kross Method!
2+
3Ca As
Ca3As2
Just kris kross the
positive and the
negative charges
1+
1Na Cl
4+
2Pb O
NaCl
Pb2O4
Calcium and Fluorine
Step 1: Use the octet rule to write the ions separately.
Step 2: Kris-Cross the charge to make subscripts.
2+
Ca
F
CaF2
The subscripts shows the proportion of
cations to anions. Here, it is 1:2.
 List the original ions, the chemical formula for the
compound formed (with the correct proportions of
ions for an overall neutral charge), and the compound
name.
1. Sodium and Chlorine
+
Na
Cl
NaCl
Sodium Chloride