1. Ionic Bonds And Ionic Compounds
Section 7.2
Ionic Bonds
And
Ionic Compounds

2. Formation of an Ionic Bond
Compound
A chemical combination of two or more different elements
Binary compounds when there are exactly two different elements

3. Formation Na + Cl  Na+ + Cl- + energy
P. 210 shows chemical reactions that form ionic bonds and release energy
Sodium and chlorine gas produce a white crystalline solid
Na + Cl  Na+ + Cl- + energy
This is called a chemical equation.

4. What Happened? + Sodium transferred one valence electron to chlorine.
[Na]+ + [Cl]- + energy +
This is the electron-dot structures

5. Types of Ionic Compounds
Electrostatic force holds the charged atoms together is the ionic bond.
Metal and non-metal ionic bond are called oxides.
Most other ionic compounds are called salts.

6. Names Sodium + Chlorine forms sodium chloride Sodium is a metal
Chlorine is a non-metal
Change chlorine to chloride in the name of the compound

7. p. 210 b
Ribbon of magnesium metal burns in air, it forms the ionic compound magnesium oxide.
Magnesium is a metal
Oxygen is a non-metal
Notice the name, oxygen became oxide.
Is this a binary ionic compound?

8. Questions Explain how an ionic compound forms from these elements
sodium and nitrogen
lithium and oxygen
strontium and flourine
aluminum and sulfur

9. Challenge Question
11. Explain how elements in group 1 and group 15 combine to form an ionic compound.

10. Properties of Ionic Compounds
Physical structure
Ratio of positive and negative ions
Ions are packed into repeating pattern
Balance the forces of attraction and repulsion between ions
* No single unit of Na and Cl exists, there are many Na+ and Cl- ions in a 1 to 1 ratio.

11. Question
What determines the ratio?

12. Common Ionic Compounds
Carpet: calcium carbonate
Ceramics/glass: calcium carbonate, lithium borate, magnesium silicate, sodium carbonate
Glossy Paper: aluminum silicate, calcium carbonate, sodium sulfate, calcium oxide, sodium carbonate, titanium(IV) oxide
Toothpaste: calcium carbonate, sodium carbonate, sodium-hydrogen carbonate, sodium fluoride

13. Crystal Lattice Three dimensional geometric arrangement of particles
Each positive ion is surrounded by negative ions and each negative ion is surrounded by positive ions
The number of ions and the ratio determine the size and shape

14. Examples Minerals More than 1/3 of all known minerals are silicates
Halides
Borates
Carbonates
What elements do you think are in these?

15. Physical Properties Melting point Boiling point Hardness
Depends on how strong the ionic attraction is
Ionic crystals are hard, rigid, brittle solids, hard to break apart – high melting and boiling points
Conduct electricity
Solids: ions are locked into place, cannot conduct electricity
Melt or dissolve solids into solutions
Electrolytes are solutions that conduct electricity and important to humans

16. Energy Endothermic Energy is absorbed Exothermic Energy is released
Formation of ionic compounds
Forms more stable system so lower energy state, release energy

17. Math / Graph
Make a scatterplot of Interionic Distance and Lattice Energy
Title_______________
(kJ/mol)
(μm)

18. Lattice Energy and Interionic Distance
Ionic Radius: the sum of the radii of each ion
Li+: 76 μm
F-: 133 μm
Cl-: 181 μm
I-: 220 μm
Find
LiF, LiCl, LiI
Lattice Energy
LiF: kJ/mol
LiCl: kJ/mol
LiI: kJ/mol
Plot each ionic compound
Use a different color for each point and label

19. Relationship
Use your graph to describe the relationship between the interionic distance and lattice energy.
Fill in the blanks:
As interionic distance ________, lattice energy ___________.

20. Lattice Energy
Energy required to separate 1 mol of the ions in an ionic compound
The greater the lattice energy, the stronger the force of attraction ( harder to separate)

21. Predict Use your graph to estimate the lattice energy for LiBr.
The ionic radius of Br- is 196 μm.

22. Patterns in Lattice Enery
Make a line graph of compound versus lattice energy (kJ/mol)
Make each set of compounds
a different color, 4 colors
Li set – blue
Na set – red
K set – green
Rb set - orange

23. Compound Lattice Energy LiF LiCl LiBr LiI -1032 -852 -815 -761 NaF
NaCl
NaBr
NaI
-926
-786
-752
-702 KF
KCl
KBr KI
-813
-717
-689
-649
Make each set of compounds a different color
Li set – blue
Na set – red
K set – green
Write a few sentences to describe any pattern you see.

24. Prediction Predict the shape of the graph of the lattice energies of
RbF, RbCl, RbBr, RbI

25. Add to Graph in Orange
Add the Rb___ compounds to your graph in orange to verify your prediction.
RbF 774

26. Summary
Ionic compounds contain ionic bonds formed by the attraction of oppositely charged ions.
Ions in a ionic compound are arranged in repeating patterns known as a crystal lattice.
Ionic compounds properties are related to ionic bond strength.

27. Ionic compounds are electrolytes; they conduct an electric current in the liquid phase and in aqueous solution.
Lattice energy is the energy needed to remove 1 mol of ions from its lattice.

28. Questions
Explain how an ionic compound made up of charged particles can be neutral?
Describe the energy change associated with ionic bond formation, and relate it to stabillity.
Identify three physical properties of ionic compounds that are associated with ionic bonds, and related them to bond strength.

29. Explain how ions form bonds, and describe the structure of the resulting compound.
Relate lattice energy to bond strength.
Use electron configurations, orbital notations and electron dot structures to represent the formation of an ionic compound from the mental strontium and the non-metal chlorine.

30. Question
Using the elements aluminum and oxygen, determine the formula for the ionic compound.
Extension: Use Fe2+ and Fe3+ to combine with O2-
Determine the formula for the ionic compounds.

31. Each Student List a metal and a non-metal
Exchange papers and determine the ionic compound formed between them.

32. Exit Ticket
Determine the ionic compound formed from Mg and Cl and explain how it was formed.
Include its ratio