1. Ionic and Metallic Bonding Chapter 7
Chemistry 2

2. Ions 7.1

3. Valence Electrons 7.1 the e- in the highest occupied energy level
Elements are alike b/c same # of valence e-
Look at group # to find
He = exception
Group 1A = 1
Group 2A = 2
Group 3A = 3
Usually used in bonding
Electron Dot Configuration – diagram that shows valence e-

4. The Octet Rule 7.1
When forming compounds, elements try to achieve an e- configuration like noble gases
Set of 8
Metallic elements tend to lose e-
Nonmetallic tend to gain or share e-

5. Formation of Cations 7.1 + charge ion Loses valence e-
Name the same as Neutral Element
(Na) = Sodium  (Na+) = Sodium ion
Chemical differences when changes
Na loses 1 e- so now has e- configuration of Neon
Mg (group 2A) loses 2e- = Mg2+ = now e- conf of Neon
Ions with more than 3 charge can happen but are not likely

6. Formation of Anions 7.1 Negative charge Gain e-
Name not the same as the neutral element
Ends in –ide
(Cl) Chlorine = (Cl-) Chloride ion
Cl gains 1 e- to have same e- configuration as Ar
Halide Ions – ions produced when halogens gain e-
Halogens = 7 valence e-  gain 1 e- = octete rule

7. Ionic Bonds and Ionic Compounds 7.2

8. Formation of Ionic Compounds 7.2
Cations + anions = ionic compounds
Neutral
Ex: table salt = NaCla
Transfer of e-
Attracted to one another b/c of opposite charge = ionic bonds = electrostatic force
Equal number of cations and anions
Chemical formula – shows kinds and umbers of atoms in smallest representative units
Ex: NaCl
Formula Unit – lowest whole-number ratio of ions in an ionic compound
NaCl = 1:1
MgCl2 = 1:2
AlBr3 = 1:3
Page 196 – Practice Problems

9. Properties of Ionic Compounds 7.2
Most solid at room temp
Some form crystals = repeating 3-D pattern
NaCl = each Na surrounded by 6 Cl ions
Each Cl surrounded by 6 Na and so on
= very strong and stable compounds
High Melting Points
Coordination number - # of ions of opposite charge that surround the ion in a crystal
NaCl = 6
Conduct electric current when melted or dissolved in water
Cations(+) migrate to cathode (-)
Anions (-) migrate to anode (+)

12. Bonding in Metals 7.3

13. Metallic Bonds and Metallic Properties 7.3
Metals = closely packed cations (+)
Valence e- are mobile and drift from one part of metal to another = sea of electrons
Metallic Bonds – attraction of free-floating valence e- for the positively charged metal ions
Good conductors b/c electrons can flow freely in them
Ductile (drawn into wire)
Malleable
e- slide past one another

14. Crystalline Structure of Metals 7.3
Metals are crystalline
Atoms arranged in very compact and orderly pattern
Patterns
Body Centered Cubic
Every atom, besides those at surface have 8 neighbors
Ex: Na, K, Fe, Cr, W
Face-Centered Cubic
12 neighbors
Ex: Cu, Ag, Au, Al, Pb
Hexagonal Close-Packed
Hexagonal shape
Mg, Zn, Cd

15. Alloys 7.3
Mixtures composed of 2 or more elements (1 which is a metal)
Ex: Brass – copper and zinc
Properties are normally better
Sterling Silver (silver and copper)
Harder and more durable than silver
Bronze (7 parts copper, 1 part tin)
Harder and more easily cast
Steel
Iron, Carbon, Boron, Chromium, Manganese, Molybdenum, nickel, tungsten, and vanadium

16. Technology and Society Building With Alloys
Taller, lighter, buildings b/c of steel
Support large, open interior w/o supporting walls