1. Chemistry Chapter 15 Ionic Bonding and Ionic Compounds
Remember what ionic bonding is?
One atom steals e-, one gives up e-
What determines how many e- they give up? Egg valence e- demo

2. Sec 15.1 Electron Configuration in Ionic Bonding
Objectives:
Use the periodic table to infer the number of valence electrons in an atom and draw its electron dot structure.
Describe the formation of cations from metals and of anions from nonmetals.

3. Valence Electrons
Valence electrons are responsible for chemical bonding and chemical properties among groups. They are the electrons in the highest occupied energy level of an element’s atom.
The number of valence electrons is related to the group numbers in the periodic table.
Use back row to visualize valence e-

4. Valence Electrons
Electron dot structures are diagrams that show the valence electrons as dots around the symbol.

5. Write the electron dot structures for each of the following elements.Cl S Al Li

6. Electron Configurations for Cations
Gilbert Lewis said atoms form certain kinds of compounds and ions in order to achieve a noble gas configuration, because they are un- reactive.
Octet Rule – in forming compounds and ions, atoms tend to achieve the noble gas electron configuration (8 electrons)
Have 8 valence e-
ns2 np6 – General Formula

7. Octet Rule for Cations
Metals will lose 1 to 3 electrons to achieve a configuration of the nearest noble gas
This makes them a cation (+ charge)
Also happens in chemical bonding
Before slide: do alkali metals lose or gain e- when becoming ions? How many?
3 legged cat do 3 or 4 examples
Neon

8. Octet Rule for Cations Group 1A elements have 1 valence e- (lose 1 e-)
Na. → Na+ + e-
Group 2A elements have 2 valence e- (lose 2 e-)
Mg: → Mg2+ + 2e-
Group 3A elements (only the metals) have 3 valence electrons to lose.
→ Al3+ + 3e-
Using an electron dot structure, show the ionization of Barium:
Silver, copper (1), gold (1), mercury (2)

9. Octet Rule for Cations For transition metals, the charges vary.
Iron, for example, may lose two or three electrons.
Fe = [Ar]4s23d6
Fe2+ = [Ar] 3d6
Fe3+ = [Ar] 3d5
Write the electron configuration for Zn2+.
Zn =[Ar]4s23d10
Zn2+ = [Ar]3d10
Silver, copper (1), gold (1), mercury (2)

10. Pseudo Noble Gas Configurations
Some transition metals don’t have noble gas configurations, but can achieve them by moving an s1 electron to make a full d-subshell.
These elements have pseudo noble gas configurations, with d-block electrons in the valence shell.
Silver, copper, gold, cadmium, and mercury are examples (elements at the right of the transition metal block)

11. Write the electron configuration for each of the following:
Cu+
Cu = [Ar]4s23d9
Cu+ = [Ar]4s13d9 or [Ar]3d10
Au+
Au = [Xe]6s24f145d9
Au+ = [Xe]6s14f145d9 or [Xe]4f145d10

12. Octet Rule for Anions
Nonmetals will gain 1-3 electrons to achieve the nearest noble gas configuration. The negative charge makes it an anion.
Group 15 nonmetals have 5 valence electrons (gain 3 e- to complete the octet)
+ 3e- → N3-
Group 16 nonmetals have 6 valence electrons (gain 2 e- to complete the octet)
+ 2e- → O2-
Group 17 nonmetals have 7 valence electrons (gain 1 e- to complete the octet)
+ e- → F-
What do halogens do to be noble gases?
Give 3 or 4 examples
Tell about chlorine (p 417 chem & tech)
White board races: write e- dot configs and e- configs of ions

13. Write electron configurations for the following anions.
[Ne]3s23p4 + 2e- = [Ne]3s23p6 = [Ar]
Cl1-
[Ne]3s23p5 + e- = [Ne]3s23p6 = [Ar]
P3-
[Ne]3s23p3 + 3e- = [Ne]3s23p6 = [Ar]
All of these ions have the same noble gas configuration as argon, since they are row three atoms gaining electrons to become stable.

14. Sec 15.1 Electron Configuration in Ionic Bonding
Did We Meet Our Objectives?
Use the periodic table to infer the number of valence electrons in an atom and draw its electron dot structure.
Describe the formation of cations from metals and of anions from nonmetals.

15. Sec 15.2 Ionic Bonds Objectives:
List the characteristics of an ionic bond.
Use the characteristics of ionic compounds to explain the electrical conductivity of ionic compounds when melted and when in aqueous solutions.

16. Formation of Ionic Compounds
Ionic compounds are bonded by the electrostatic attraction of a cation (+) to an anion (-).
These bonds are called ionic bonds.
The compound is electrically neutral.
The total positive charge must equal the total negative charge.
Before slide: what is an ionic bond?
Link to food science (p418)
Become neutral after bonding
Na got on eHarmony and found Cl

17. Potassium and Sulfur Aluminum and Sulfur
Use the electron dot structures to predict the formulas of the ionic compounds formed from these elements.
Potassium and Sulfur
Aluminum and Sulfur
HF HCl MgI2 Na2S MgCO3
Write like in book

18. Write the correct chemical formula for the compounds formed from each pair of ions.
K+ and S2-
K2S
Ca2+ and O2-
CaO
Na+ and SO32-
Na2SO3
Al3+ and SO42-
Al2(SO4)3

19. Properties of Ionic Compounds
At room temperature ionic compounds properties include…
Repeating Patterns
Crystalline solids
Strong bonds
Minimal repulsion
Stable Structure
High melting points
Get crystals Use ball and sticks
Why brittle? Repulsion if moved
Waterford & lead poisoning

20. Properties of Ionic Compounds
Coordination number of an ion is the number of ions of opposite charge that surround the ion in a crystal.
Na+ and Cl- have coordination numbers of 6 in NaCl crystal. They each have six ions surrounding them.
The coordination number depends on the shape of the crystal. The charges and relatives sizes of the ions determines the crystal structure.
Chem & enviro (p422) rust and Al2O3
Diamond & graphite Coord #

21. Properties of Ionic Compounds
The internal structures of crystals are determined by a technique called X-ray diffraction crystallography.
X-rays pass through a crystal are recorded on film.
The pattern on the exposed film shows how ions in the crystal deflect the x-rays.
X-ray diffraction like holding a flashlight
Before slide: do ions conduct electricity?
Minilab (p425) or demo
Chemical bonds lab then review

22. Properties of Ionic Compounds
Ionic compound crystal structures can break down. This occurs when the ionic compound is melted or dissolved. Properties are different in this state:
conduct electricity
Ions dissociate and are free to move
X-ray diffraction like holding a flashlight
Before slide: do ions conduct electricity?
Minilab (p425) or demo
Chemical bonds lab then review

23. Sec 15.2 Ionic Bonds Did We Meet Our Objectives?
List the characteristics of an ionic bond.
Use the characteristics of ionic compounds to explain the electrical conductivity of ionic compounds when melted and when in aqueous solutions.

24. Sec 15.3 Bonding In Metals Objectives:
Use the theory of metallic bonds to explain the physical properties of metals.
Describe the arrangements of atoms in some common metallic crystal structures.

25. Metallic Bonds and Metallic Properties
Metals consist of closely packed cations
They are in a “sea” of valence electrons
Metallic bond – consists of the attraction of the free floating valence electrons for the positively charged metal ions.
Demo: metal samples
Give students tennis palls: they can pass around

26. Metal Bonds and Properties
Metallic bonding explains metallic properties
Electricity, ductility, malleability
Valence e- move easily and insulate cations from each other. Under pressure, the metal cations can easily slide past one another.
Explain malleability, push desks while they pass balls around. Why is it not good to play golf in storm? Explain electricity, have them all throw it at me

27. Crystalline Structure of Metals
Metals are also in crystal form
Metal atoms are arranged in very compact and orderly patterns, like tennis balls in a box
Have 3 different arrangements
Body-centered cubic, face-centered cubic, hexagonal close- packed
Body-Centered Cubic
Face-Centered Cubic
Hexagonal Close-Packed
Demo: make these with ball & sticks?
Gold: face centered cubic
Zinc: hexagonal close packed

28. Alloys
Alloys are mixtures composed of two or more elements, at least one of which is metal.
Most metals you encounter aren’t pure elements.
Amalgams are alloys that contain mercury.
Before slide: what type of metal is ……
Bronze: copper, tin brass: copper, zinc
Sterling silver: silver, copper
Stainless: Fe, Cr, C, Ni
Use students to demonstrate bottom part

29. Alloys
Types of alloys
Substitutional alloy – The atoms of the components in an alloy are about the same size, they can replace each other in the crystal.
Interstitial alloy – The atomic sizes are quite different, and the smaller atoms can fit into the interstices (spaces) between the larger atoms.

30. Sec 15.3 Bonding In Metals Did We Meet Our Objectives?
Use the theory of metallic bonds to explain the physical properties of metals.
Describe the arrangements of atoms in some common metallic crystal structures.