1. Chapter 8
IONIC COMPOUNDS

2. Section 8.1—Forming Chemical Bonds
The force that holds two atoms together is called a chemical bond.
Negative electrons are involved in the formation of bonds.
*Review*
electron dot structures
ionization energy
stable atoms

3. Electron dot structures
[Ar] 4s2 3d10 4p4
# of valence electrons?
Group #?
We need to know this to draw e- dot.

4. Ionization energy
What is IE?
Across a period?
Down a group?

5. Stable atoms What are the most stable elements?
What makes them stable?
How can other atoms become stable?

6. Section 8.1—Forming Chemical Bonds
Positive ions form when an atom loses an electron. This is called a cation.
Remember?

7. Reactivity is based on how easily metals lose a valence electron.
The two most active groups of metals are the Group 1A & 2A elements.
Transition metals can also lose d sublevel electrons.
In general, metals lose 1, 2, & sometimes 3 electrons.

8. Section 8.1—Forming Chemical Bonds
Negative ions form when a nonmetal gains an electron. This is called an anion.
The negative ion of chlorine is chloride. Nitrogen is nitride. Fluorine is fluoride.
In general, nonmetals usually gain 1, 2, or 3 electrons.

9. Example What ion is formed from the following atoms? Chlorine Cl-1
Nitrogen
N-3
Barium
Ba+2

10. Practice
Work practice problems #1-8

11. 1. How do the 2 images of iron nails differ in appearance & in their properties?
2. What chemical reaction do you think caused the appearance of the nails on the right?

12. Section 8.2—The Formation & Nature of Ionic Bonds
During the formation of an ionic bond, valence electrons are transferred from one atom to another, resulting in the ions.
Binary compounds contain only 2 different elements.
Na + Cl  Na+1 Cl-1

14. Example8-1
Unprotected aluminum metal reacts with oxygen in air, forming a white coating you can observe on aluminum objects such as lawn furniture. Explain the formation of an ionic compound from the elements aluminum & oxygen.
(check by calculating the overall charge)

15. Try practice problem # 1 & # 2
Want to know a shorter way?
Work #3-6, then 7-9

16. Bell Ringer 1. How does an ionic bond form?
2. Why is CaSO4 not a binary compound?

17. Section 8.2—The Formation & Nature of Ionic Bonds
A crystal is regular repeating pattern that balances the forces of attraction & repulsion of ions during the formation of an ionic compound.
A salt (NaCl) crystal is shaped like a cube.
Melting point, boiling point, & hardness are physical properties that depend on how strong the attraction between ions.

20. Section 8.2—The Formation & Nature of Ionic Bonds
An electrolyte is an ionic compound whose aqueous solution conducts an electric current.

21. Remember that during any chemical reaction, energy is either absorbed or released. If energy is absorbed, it is known as an endothermic reaction. If energy is released, it is known as an exothermic reaction. The formation of ionic bonds is always exothermic.

22. The formation of ionic bonds is always neutral.
Stop

23. Section 8.3—Names & Formulas for Ionic Compounds
The simplest ratio of ions in a compound is called a formula unit.
ie. KBr is a 1:1 MgCl2 is a 1:2 ratio
Three sodium ions for every one phosphide ion is Na3P
The overall charge of a formula unit is zero.
A monatomic ion is a one-atom ion.
ie. Formula for the iodide ion is I-1. Calcium ion is Ca+2. Nitride ion is N-3.

24. An oxidation number or oxidation state is the charge of a monatomic ion. The oxidation numbers are used to determine the formulas for the ionic compounds they form.
In the chemical formula for any ionic compound, the cation is written first. The anion is written next. Subscripts represent the number of ions of each element in an ionic compound.

25. Section 8.3—Names & Formulas for Ionic Compounds
Polyatomic ions are ions made up of more than one atom. The charge applies to the entire group of atoms. It acts as an individual ion. NEVER CHANGE SUBSCRIPTS WITHIN ION. Place parentheses around the ion if more than one is needed.
An oxyanion is a polyatomic ion composed of an element with oxygen atom(s). Its name comes from the element other than oxygen.

26. Compounds formed with polyatomic ions
Example:
A common ionic compound in fertilizers is formed from calcium & phosphate ions. Write the correct formula for this compound.
Work practice problems

27. Section 8.3—Names & Formulas for Ionic Compounds
Naming Compounds
Binary—2 elements only
Name the cation. (element name)
Name the anion. (root of the element plus –ide)
Example:
1. KCl
2. Magnesium iodide

28. Practice:
1. AlF3
2. Na3N
3. Magnesium nitride

29. If the cation has more than one oxidation number, use a roman numeral.
Example:
FeO
Iron (III) oxide

30. Practice:
1. Cu2S
2. NiCl2
3. Cr2O3
4. Iron (II) sulfide

31. Ternary Compounds—contains at least one polyatomic ion
Name cation
Name anion
Example:
Ba(NO3)2

32. 1. K2SO4
2. CaCO3
3. Cu(NO3)3 transition metal
4. Mg3(PO4)2
5. Copper (II) carbonate
6. Magnesium iodate

33. 8.4- Metallic Bonds & Properties of Metals
The electron sea model says that all metal atoms in a metal is solid contribute their valence electrons to form a “sea” of electrons.
Delocalized electrons are the e- in the outer energy level of metallic atoms because they are free to move about, NOT held by a specific atom.

35. Pic of mallea,duct, cond

36. Properties of metals They have variable melting points.
Are malleable- can be hammered into sheets
Are ductile- can be drawn into wire
Good conductors because the delocalized e- move the heat from one place to another very quickly & easily.

37. Alloy- mixture of elements that have metallic properties.
Example
Steel- Fe & C
Pewter- Sn, Sb, Pb
Sterling silver- Ag & Cu