1. Ch. 7 Ionic and Metallic Bonding

2. 7.1 Ions

3. Valence Electrons
Electrons in the highest occupied energy level of an atom
Number determines chemical properties of an element
Find by looking at group number (1A-8A)
Shown in electron dot structures
Octet rule: in forming compounds, atoms tend to achieve the electron configuration of a noble gas (fill the octet)

4. Formation of Cations
Positively charged ions are formed when an atom loses one or more valence electrons

5. Transition Metals Form cations
Some form multiple ions (with different charges)
Not all achieve pseudo-noble gas configuration

6. Formation of Anions
An atom gains one or more valence electrons

7. 7.2 Ionic Bonds and Ionic Compounds

8. Formation of Ionic Compounds
Ionic compound: composed of cations and anions
Electrically neutral (cation and anion charges balance each other)
Ionic bond: electrostatic forces that hold ions together in ionic compounds (interaction between cation and anion)

9. Use electron dot structures to determine formulas of the ionic compounds formed when the following elements react.
Potassium and Bromine
Sodium and Sulfur
Magnesium and Nitrogen
Calcium and Chlorine

10. Formula Units
Chemical formulas show the number of atoms of each element in the smallest representative unit of a substance (molecules, formula units, atoms, etc.)
Formula unit is the lowest whole number ratio of ions in an ionic compound
Between a +1 cation and a -1 anion, the ratio is one-to- one, such as NaCl
Between a +2 cation and a -1 anion, the ratio is 1 to 2, such as MgCl2

11. Water Testing
Potassium thiocyanate indicates presence of iron(III) ions if a red color forms
Sodium oxalate indicates the presence of calcium ions if a white precipitate forms
In both cases, the formation of a new ionic compound indicates the presence of a particular ion in the water.

12. Properties of Ionic Compounds
Crystalline solid at room temperature
High melting points
Coordination number: number of ions of opposite charge that surround the ion in a crystal
Conduct electricity when melted or dissolved in water

14. 7.3 Bonding in Metals

15. Metallic Bonds
Metallic bonds are forces of attraction between free- floating electrons and positively charged metal ions
Sea of electrons model
Conductivity
Malleability

16. Alloys Mixture of 2+ elements including at least 1 metal
Properties are often superior to pure elements
Oxidation, hardness, malleability, conductivity
Common alloys include stainless steel, sterling silver, and cast iron

17. Electrolysis Simulation