1. PAP Chapter 6 CHEMICAL BONDING
Cocaine
To play the movies and simulations included, view the presentation in Slide Show Mode.

2. Chemical Bonding
A chemical bond is a mutual electrical attraction between the nuclei and valence electrons of different atoms that binds the atoms together

3. Characteristics of Metals
Ductile- draw into thin wire
Malleable-ability to hammer into
Thin sheets
Shiny (luster)
Conducts heat and electricity
Solid at room temperature

4. Metallic Bonding Metallic – holds atoms of metals together
A metallic bond is formed between all metals. Examples include a piece of Copper, Zinc, Sodium, Iron. Any metal
Metallic bonds result from the attraction between metal atoms and the surrounding sea of delocalized electrons
valence electrons can move freely around the whole metal structure—they are not confined to any one atom

5. Metallic Bonding This model explains many of the properties of metals:
the mobile electrons can enter/leave the metal structure, so metals are good conductors of heat and electricity!
metal cations are not locked into any crystal structure, so they can slide past each other when stressed. That makes metal malleable and ductile.
The de-excitation ( The electron falling back down to a lower energy level) is responsible for the shiny (luster) appearance of metals.

6. Ionic Bonds
complete transfer of 1 or more electrons from one atom to another (one loses, the other gains) forming oppositely charged ions that attract one another

7. Remember Cations and Anions
An atom which loses an electron becomes positively charged and is called a cation.
Examples: Na+, K+, Ca2+, Al3+
Metals usually become cations
An atom which gains an electron becomes negatively charged and is called an anion.
Nonmetals usually become anions.
Examples: Cl-, S2-, N3-

8. Characteristics of Ionic Bonds
The electrons align themselves into an orderly arrangement that is known as crystal lattice. This makes the shape that you see into a crystal.

9. Characteristics of Ionic Compounds
Strong attraction between ions
Soluble in water
Conduct electricity in solution
Conduct electricity when molten
High melting points
High boiling points
Hard but brittle
Solid at room temperature

10. What are electron dot formulas or Lewis Dot Diagrams
Electron dot formulas are diagrams that show valence electrons in the atoms of an element as dots around the symbol of the element.
1. Make Generalizations As illustrated by the electron dot formulas in the table, how are the elements in a group similar?

11. How are electron dot formulas for ionic bonds constructed?
Ionic bonds form as a result of electrostatic attractions between cations and anions.
Electron dot formulas show the valence electrons and charges of these ions and may be used to illustrate the ionic bonds.

12. Examples

13. Examples Lithium and Bromine Magnesium and Chlorine Sodium and Sulfur
Aluminum and Oxygen

14. Day 2

15. Covalent Bonds :
Covalent —valence electrons are shared between nonmetal atoms

16. Covalent Bond
Nonpolar Covalent bond- Covalent bond in which the bonding electrons are shared equally by the bounded atoms, resulting in a balanced distribution of an electrical charge.
Polar Covalent bond- Covalent bond in which the bonded atoms have an unequal attraction for shared electrons.
Each atom has a charge
Partial positive- (+δ)
Partial negative- (- δ)

17. Characteristics of Covalent Bonds
Two non-metals bonded together
Relatively weak bonds
Usually a gas or liquid at room temperature
Does not conduct electricity in solution
Low melting point
Low boiling point
Soluble in alcohol and insoluble in water

18. The type of bond can usually be calculated by finding the difference in electronegativity of the two atoms that are going together.
Electronegativity
Decreases
Electronegativity
Increases

19. Electronegativity Difference
If the difference in electronegativities is between:
1.8 to 4.0: Ionic
0.4 to 1.7: Polar Covalent
0.0 to 0.3: Non-Polar Covalent
Example: H2O
H = 2.1, O = 3.5
Difference is 1.4, so
this is a polar covalent bond !
Example: NaCl
Na = 0.9, Cl = 3.0
Difference is 2.1, so
this is an ionic bond!

20. Diatomic Molecules Diatomic Molecules are nonpolar covalent compounds.
A diatomic molecule is a molecule only containing two atoms
The seven diatomic molecules are
H2, N2, O2, F2, Cl2, Br2, I2
These diatomic molecules are never by themselves.

21. Lets Build Lewis Dot Diagrams
Day 3

22. Octet Rule
Chemical Compounds tend to form so that each atom, by gaining, losing or sharing electrons, has an octet of eight electrons in its highest occupied energy level

23. Electron dot formulas:covalent bonds
In a covalent bond, no ions form. Instead, nonmetallic atoms share electrons, which results in each atom having a noble-gas configuration.
Single Covalent Bonds -A single covalent bond results when two atoms share one pair of electrons, as in the case of hydrogen gas, which is a diatomic molecule.

24. Examples: F2 , HBr, Cl4
(contd.)

25. Double Covalent Bonds- When atoms bond by sharing two pairs of electrons, the result is a double covalent bond, as in a molecule of carbon dioxide, CO2. The double bond is shown by four dots or two dashes.

26. Triple Covalent Bonds- When atoms bond by sharing three pairs of electrons, the result is a triple covalent bond, as in a molecule of nitrogen gas, N2. The triple bond is shown by six dots or three dashes.

27. Violations of the Octet Rule
Usually occurs with B and elements of higher periods. Common exceptions are: Be, B, P, S, and Xe.
SF4
Be: 4
B: 6
P: 8 OR 10
S: 8, 10, OR 12
Xe: 8, 10, OR 12
BF3

28. Lewis Structures HF or H - F H F or H - O - H H O H H2O · · · · · ·

29. Lewis Structures H N H NH3 or H - N - H H H or H - C - H CH4 H C H H H
· ·
NH3
· ·
or H - N - H H
or H - C - H H
H C H H
· ·
CH4

30. Extra Slides

31. Bond Polarity
H2O is POLAR because it has a positive end and a negative end. (difference in electronegativity)
O has a greater share in bonding electrons than does H.
O has slight negative charge (-δ) and H has slight positive charge (+ δ)

32. Bond Polarity
This is why oil and water will not mix! Oil is nonpolar, and water is polar.
The two will repel each other, and so you can not dissolve one in the other

33. Bond Polarity “Like Dissolves Like” Polar dissolves Polar
Nonpolar dissolves Nonpolar
Polar also dissolved Ionic
Ex: water and salt