Transcript The Formation and Nature of Ionic Bonds DO Now: Standard I&E: 2a, 2c, 7b Terms: 215 Mastering Concepts: 236 (51-53) Practice Problems: 217(7-9) Homework: Cornell Notes: 8.2 Section.

The Formation and Nature of Ionic Bonds
DO Now:
Standard I&E: 2a, 2c, 7b
Terms: 215
Mastering Concepts: 236 (51-53)
Practice Problems: 217(7-9)
Homework:
Cornell Notes: 8.2
Section Assessment: 220(12-17)
Mastering Problems: 236 (67-73)
8 Stamps
Section 8.2 Ionic Bonds and Ionic Compounds
Section 8-2
• Describe the formation of ionic bonds and the structure
of ionic compounds.
• Generalize about the strength of ionic bonds based on the
physical properties of ionic compounds.
• Categorize ionic bond formation as exothermic or
endothermic.
compound: a chemical combination of two or more
different elements
Section 8.2 Ionic Bonds and Ionic Compounds (cont.)
Section 8-2
ionic bond
ionic compound
crystal lattice
electrolyte
lattice energy
Oppositely charged ions attract each other,
forming electrically neutral ionic compounds.
Formation of an Ionic Bond
Section 8-2
• The electrostatic force that holds oppositely
charged particles together in an ionic compound
is called an ionic bond.
• Compounds that contain ionic bonds are called
ionic compounds.
• Binary ionic compounds contain only two different
elements—a metallic cation and a nonmetallic
anion.
Formation of an Ionic Bond (cont.)
Section 8-2
Properties of Ionic Compounds
Section 8-2
• Positive and negative ions exist in a ratio
determined by the number of electrons
transferred from the metal atom to the non-metal
atom.
• The repeating pattern
of particle packing in
an ionic compound is
called an ionic crystal.
Properties of Ionic Compounds (cont.)
Section 8-2
• The strong attractions among the positive and
negative ions result in the formation of the
crystal lattice.
• A crystal lattice is the three-dimensional
geometric arrangement of particles, and is
responsible for the structure of many
minerals.
Properties of Ionic Compounds (cont.)
Section 8-2
• Melting point, boiling point, and hardness
depend on the strength of the attraction.
Properties of Ionic Compounds (cont.)
Section 8-2
• In a solid, ions are locked into position and
electrons cannot flow freely—solid ions are
poor conductors of electricity.
• Liquid ions or ions in aqueous solution have
electrons that are free to move, so they conduct
electricity easily.
• An ion in aqueous solution that conducts
electricity is an electrolyte.
Properties of Ionic Compounds (cont.)
Section 8-2
• This figure demonstrates how and why crystals
break when an external force is applied.
Energy and the Ionic Bond
Section 8-2
• Reactions that absorb energy are endothermic.
• Reactions that release energy are exothermic.
Energy and the Ionic Bond (cont.)
Section 8-2
• The energy required to separate 1 mol of ions
in an ionic compound is referred to as the
lattice energy.
• Lattice energy is directly related to the size of the
ions that are bonded.
Energy and the Ionic Bond (cont.)
Section 8-2
• Smaller ions form compounds with more
closely spaced ionic charges, and require more
energy to separate.
• Electrostatic force of attraction is inversely related
to the distance between the opposite charges.
• The smaller the ion, the greater the attraction.
Energy and the Ionic Bond (cont.)
Section 8-2
• The value of lattice energy is also affected by
the charge of the ion.
Naming Ionic Compounds
Rules
1. Name Cation
2. Use Roman Numerals if the metal is a
transition metal (Exceptions: Zn, Ag, Al)
3. Name the Anion (It may be a polyion)
4. Add the -suffixes:
-ide = salts comprised of only two elements;
– -ate, -ite = compounds containing a (usually
metal) cation ion and a complex anion
(usually involving oxygen);
15
Examples: From Name to Formula
1. Sodium oxide: Na +1 O2Na1+
Na2O
2. Magnesium nitride: Mg2+ N3+6
-6
Mg3 N2
18
Examples: From Name to Formula
3. Iron III chloride
Fe+3 ClFe+3 Cl- Cl- Cl-
= FeCl3
19
Practice Problems: 217 (7-11)
Explain the formation of the ionic compound
composed of each pair of elements.
7. Sodium and nitrogen
8. Lithium and oxygen
9. Strontium and fluorine
10. Aluminum and sulfur
11. Cesium and phosphorus
20
Practice Problems: 217 (7-11)
Explain the formation of the ionic compound composed of
each pair of elements.
7. Sodium
Na
Symbol
Group #/valence
1e
electrons
Easier to lose or gain
electrons to satisfy Lose 1e
the octet rule
Na+1
Charge
Nitrogen
N
5e
Gain 3e
N-3
Na3N
21
Practice Problems: 217 (7-11)
Explain the formation of the ionic compound composed of
each pair of elements.
8. Lithium
Li
Symbol
Group #/valence
1e
electrons
Easier to lose or gain
electrons to satisfy Lose 1e
the octet rule
Charge
Li+1
Li2O
Oxygen
O
6e
Gain 2e
O-2
22
Practice Problems: 217 (7-11)
Explain the formation of the ionic compound composed of
each pair of elements.
9. Strontium Fluorine
Sr
F
Symbol
Group #/valence
2e
electrons
Easier to lose or gain
electrons to satisfy Lose 2e
the octet rule
Sr+2
Charge
7e
Gain 1e
F-1
SrF2
23
Practice Problems: 217 (7-11)
Explain the formation of the ionic compound composed of
each pair of elements.
10. Aluminum Sulfur
Al
S
Symbol
Group #/valence
3e
electrons
Easier to lose or gain
electrons to satisfy Lose 3e
the octet rule
Al+3
Charge
6e
Gain 2e
S-2
Al2S3
24
Practice Problems: 217 (7-11)
Explain the formation of the ionic compound composed of
each pair of elements.
11. Cesium
Cs
Symbol
Group #/valence
1e
electrons
Easier to lose or gain
electrons to satisfy Lose 1e
the octet rule
Cs+1
Charge
Phosphorus
P
5e
Gain 3e
P-3
Cs3P
25