1. Ionic Bonding Ch 8 CVHS Chemistry
EQ: How does the electron configuration of elements impact the Ionic Bonding?

2. Ionic Compounds Ionic Bonds Metallic bond Chemical compounds
Held together by chemical bonds
Ionic Compounds
Electrons from a metal are transferred to a nonmetal
Resulting ions held by electrostatic force
Chemical Bonds
Ionic Bonds: Metal & Nonmetal
Metallic Bonds: Metal & Metal
Covalent (molecular) Bonds: Nonmetal & Nonmetal
Ionic Bonds
Metallic bond

3. The Octet Rule & Why Ionic Bonds form
Noble gases are extremely stable
Each noble gas has eight valence electrons, except for helium, which has two
The octet rule: atoms can become stable by having eight electrons in their outer energy level
Ex: Neon, (or two electrons in the case of some of the smallest atoms).
Elements become stable by attaining the same configuration as the noble gases.

4. The Octet Rule

5. Properties of ionic compounds
Practice Problem:
What bond would form between Ca and Br?
Answer: CaBr2
Ca (4s2) + Br (4s2 4p5)
2 Br atoms take the 2 electrons from Ca and then both atoms have a noble gas configuration
Well organized, tightly bound ions w/ a crystal lattice structure. Crystalline room temp. so it takes a lot of energy to melt them to break the bonds Electrolytes: dissolve in water or melt and then conduct electricity

6. Formation of an Ionic Compound
Ionic Bonds are held together by the force of the oppositely charged particles attracting each other. Explain the formation of an ionic compound from the elements aluminum and oxygen: Aluminum: 3 Valence electrons Oxygen: 6 valence electrons To acquire noble gas configuration each oxygen takes 2 electrons and each aluminum gives 3 electrons To make the charges equal zero: Al2O3

7. Names and formulas for ionic compounds
Formula Unit: Simplest ratio of atoms in an ionic compound Overall charge is 0 Monatomic Ions: one atom Charge can be determined by location on table
Group 1A: 1+ Group 2A: 2+ Group 3A: 3+ Group 7A: 1-

8. Oxidation numbers
Mg + Br Mg2+ (3s2) Br1- (4s2 3d10 4p6) Cation is written first, Charge is written as an exponent MgBr2 Subscripts represent # of atoms Multiply subscripts by exponents charge will equal 0
The charge on the ion # of electrons transferred Used to determine chemical formulas Multiply the oxidation # by the subscript, they must = 0.

9. Ionic Formulas & Oxidation Numbers
Ionic Formula Rules:
Metals always form “+” ions by losing one or more valence electrons from the “s” and/or “p” sublevels.
Na = (Ne) 3s1 Lose the 3s e-
Mg = (Ne) 3s2 Lose both 3s e-
Al = (Ne) 3s2 3p1 Lose all 3 e-
Nonmetals will gain one or more electrons to form a full outer valence by the Octet Rule.
S = (Ne) 3s2 3p4 Gains 2e- in 3p
Br = (Ar) 4s2 3d10 4p5 Gains e- in 4p
Can form Co2+ (Ar) 4s2 3d5
Or Co3+ (Ar) 4s1 3d5

10. Ionic Formulas & Oxidation Numbers
Transition metals will lose electrons to create a stable “d” configuration and lose the outermost “s” electrons. Note that a half-full sublevel is also stable, but less so than an empty or full one.
Co = (Ar) 4s2 3d7
Can form Co2+ (Ar) 4s2 3d5
Or Co3+ (Ar) 4s1 3d5

11. Practice
Now that we know the charges, let’s write Ionic Formulas (Be sure charges sum to zero!):
Na++ Cl-
NaCl
Mg2+ + Br- 
MgBr2
K++ O2- 
K2O
Al3++F-
AlF3

12. Polyatomic ions A group of atoms that act as an ion.
Formulas containing Polyatomic Ions:
Na+ + OH- NaOH
Na+ +SO42-Na2(SO4)
Mg2++NO3-Mg(NO3)2
NH4++CO32-(NH4)2CO3