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Chapter 7 Ionic and Metallic Bonding

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1 Chapter 7 Ionic and Metallic Bonding
Chapter 4 Atoms and Chemical Bonding

2 Valence Electrons Highest energy level Determine chemical properties
[Ne]4s2 3d10 4p5 - Bromine 7 valence e- Representative elements = group #

3 Valence Electrons Lewis (1916)
2 3 4 5 6 7 8 Valence electrons are the electrons in the atom’s highest numbered energy level.

4 Electron dot Structures
Lewis dot Show electrons as dots Ca• •B• Fill in each side with one dot before you double up

5 Octet Rule In forming compounds atoms gain, lose, or share
in such a way that they achieve the electron configuration of the nearest noble gas in the periodic table. Noble gases are stable have eight electrons in the outermost level

6 Ionic Bonding Atoms lose or gain electrons to form ions
Cations are positive ions metals generally form cations Anions are negative ions non-metals generally form anions Ionic compounds are held together by electrostatics- the positive charge of the cation attracting the negative charge of the anion.

7 Ionic Bonding Continued

8 Ionic Compound METAL + NONMETAL Important metal ions
group 1A - loose 1 electron (+1) group 2A - loose 2 electrons (+2) group 3A - loose 3 electrons (+3) Important non-metal ions group 7A (-1), group 6A (-2), group 5A (-3)

9 Properties of Ionic bonds
Most are crystalline solids at Room temp Stable structures with all of the (+) and (-) attractions

10 Properties cont. Stable structures with all of the (+) and (-) attractions High melting points Conduct electricity Ions move freely so e- can travel toward (+) When dissolved in water

11 Ionic Bonds One cation and one anion Electrically neutral
Cation gives e- Anion takes e- Example Aluminum and bromine

12 Common Ions and Their Position in the Periodic Table

13 Lewis Structures Al • •Cl• Cl [Al] [Cl]3 Cl

14 Names of Common Nonmetallic Ions

15 Polyatomic Ions Polyatomic means “many-atom” ion

16 Metallic bonds Closely packed cations
Valence e- are free and can drift from one metal to another Meallic bonds consist of the attraction of ther free-floating valence e- for the positively charged metal ions

17 Metallic bonds (e-) they do not "belong" to any one atom
are part of the whole metal crystal *Metallic bonds are best characterized by the phrase "a sea of electrons"*

18 Metallic properties electrons flow explains characteristics of metals:
- Metals are good conductors of heat and electricity. mobility of the electrons. - The "cement" effect of the electrons determines the hardness Some -  Metals are lustrous.  due to the uniform way that the valence electrons absorb and re-emit light energy. - Metals are malleable (can be flattened) and ductile (can be drawn into wires) because the metal cations and electrons can "flow" around each other, without breaking the crystal structure.

19 Alloys Mixture of two or more elements, at least one is a metal
Example: brass = copper and zinc Properies are better than those of the single elements Sterling silver = siler and copper Durable /no tarnish Steel is a very important alloy iron, carbon, boron, chromium, manganese, and more

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