1. Chemical Bonding

2. Bellringer What types of elements form an ionic bond?
What types of elements form a covalent bond?
What are some characteristics of ionic compounds?
What are some characteristics of covalent compounds?

3. Three Types of Bonds We will study . . . Ionic Bonding
Covalent Bonding
Metallic Bonding
occurs between a metal and a nonmetal
occurs between two nonmetals
occurs WITHIN a metal sample

4. Electron Configuration
Remember that electron configuration refers to the arrangement of electrons in the orbital of an atom! 2 8 18 32

5. Ionic and Covalent Bonding Video clip

6. Chemical Bonding
Compounds are formed from chemically bound atoms or ions.
Bonding involves only the valence electrons.

7. Valence Electrons
Electrons are found in specific orbits/clouds spinning around the nucleus
Valence electrons are the electrons located in the outermost orbit
Elements become stable when:
their outer orbit contains 8 electrons or their outer orbit becomes empty
Lewis Dot Diagrams show the # of Valence Electrons

8. The Octet Rule
When the highest energy level of an atom is filled, the atom is stable.
Atoms tend to gain, lose, or share electrons until they have eight valence electrons.
Hydrogen and Helium are the only exceptions. Because they are so small, they are satisfied with two valence electrons.
Why are the noble gases unreactive?

9. Lewis Electron Dot Diagram
Lewis symbols show the valence electrons as dots arranged around the atomic symbol.
hydrogen:
sodium:
chlorine: H Na Cl
· ·

10. Dot Diagrams Show the number of valence electrons

11. Ionic Bonds form between a metal and a nonmetal
form as a result of a transfer of electrons
Na becomes a positive ion called =
Cl becomes a negative ion called =
Cation means “to go down”
– also think cast off
Anion means “to go up”
Also think accept Na Cl
· ·
Cation
Anion
So, an Ion is a Charged Particle!!!

14. Ionic Bonds
What is the formula for the compound that forms between magnesium and chlorine? Cl
· · Mg
· · Cl
· ·

15. Ionic Compounds
Ionic compounds consist of a lattice of positive and negative ions.

16. Ionic Compounds, Characteristic & Properties
High melting points
High boiling points
Conduct electric current when melted and when dissolved in solution
All of these properties are a result of the strong attraction among ions within the crystal lattice

17. Animated Reaction with sodium and chlorine

18. Naming Ionic Compounds
1) Write the name of the metal
2) Shorten the name of the non-metal and add the suffix -ide
KCl = potassium chloride
3) **If the Metal is a Transition Metal, after the metal name, give its charge in Roman Numerals
CuSO4 = Copper (II) Sulfate

19. Polyatomic Ions
If the compound contains a polyatomic ion, just name the ion as it appears on the list.

20. Practice Naming Ionics
MgBr2
PbO
Na3PO4
Na2O
CdO
KOH
Al2O3
NH4NO3
CsC2H3O2
KMNO4

21. Writing Ionic Formulas
You must balance the ions
Same amount of (+) as (-)
Sodium Sulfide Na (1+) & S (2-)
So Na2S
See p in text
Steps:
write symbols
write charges
cross-over charges from top to bottom
remove the charge
simplify numbers and remove the 1s

22. Practice Aluminum Oxide Aluminum Bromide Potassium Oxide
Sodium Chloride
Cesium Sulfide
Rubidium Fluoride
Magnesium Nitride

23. What are some of the characteristics of Ionic Bonds?
Need at least 7 facts/characteristics
3 Examples of Ionic Bonds

24. Bell ringer What is a positive ion called?
How are positive ions formed?
What are some of the characteristics of ionic compounds?

25. Covalent Bonds (Molecular Bonds)
form between two nonmetal atoms
form as a result of a sharing of electrons

26. Covalent Bonding animation

27. Polar Molecules
There is an uneven distribution of charge…one atom has a stronger attraction for the electrons than the other
Polar molecules attractions are stronger than nonpolar molecules

28. Polar covalent bonding in a water molecule animation

29. Molecular Compounds, Characteristic & Properties
Note the correct name for a compound that contains covalent bonds
Low melting points
Low boiling points
Usually gases or liquids at room temp.
Does not conduct electricity well
May or may not dissolve in water (there are several types of molecular compounds)

30. Molecular Compounds, Lewis Structures
Covalent bonding in a molecule can be represented by a Lewis structure containing bars that represent shared pairs of electrons. Cl
· · +
® Cl Cl
· ·
Bonding
electrons
Cl2
Cl Cl
· ·
Nonbonding electrons

31. Double and Triple Bonds
Atoms can share four electrons to form a double bond or six electrons to form a triple bond. =
O O
· · O2
· ·
N N  N2

34. Naming Molecular Compounds
To name molecular compounds you need to use prefixes to indicate the number of atoms of each element present. You CANNOT use prefixes to name ionic compounds only molecular

35. Naming Molecular Compounds
Prefix to indicate the number of atoms of each element in a compound's formula
Exception: "mono" is not used in front of first element's name.
Change ending of last element to "ide".
Mono-
Hexa-
Di-
Hepta-
Tri-
Octa-
Tetra-
Nona-
Penta-
Deca-

36. Practice
N2O5
SO3 CO
P4O10
As2O

37. Practice Writing Molecular Formulas
Silicon Dioxide
Carbon Monoxide
Trioxide Pentachloride
Diarsenic Hexanitride
Boron Trifloride

38. Double Bubble – Compare/Contrast Ionic and Covalent Bonding Need at least 15 fact/characteristics Need at least 3 examples of each

39. Bell Ringer
Use the criss cross method to find the formula for Magnesium Chloride.
What is the name for SiO2

40. Work in Textbook!! P. 174 – Math practice #1-4

41. Metallic Bonding Holds atoms of metals together
A metallic bond is the attraction between a metal cation and the shared electrons that surround it.
Found in pure metals (copper, iron) and alloys (steel, brass, bronze, etc)

42. Metallic Bonding
Metal atoms release their valence electrons to be shared by all metal cations
Metal cations in a “sea” of mobile valence electrons

43. The metallic bonds in some metals are stronger than in other metals.
The more valence electrons, the stronger the metallic bonds will be.
Do alkali metals have strong bonds?
NO!! Only 1 valence electron!!
What about Tungsten?
YES!!

44. Metallic Bonding, Characteristic & Properties
Good conductors of heat and electricity because of mobile electrons
High melting points because of strong attraction of positive metal ions and negative electrons
(sodium has a low melting point, Tungsten has a very high melting point…WHY?)

45. Metallic Bonding, Characteristic Properties
Lustrous
Malleable and Ductile because metal ions can slide past each other

46. Structure of Metals
Metallic bond- metal cation and shared electrons, very strong, malleable
Free moving electrons
Alloy- mixture of 2 or more elements, one of which is a metal
Ex. Gold (24-karat vs. 12-karat) (100% vs. 50% pure)

47. Sasinschools quick launch 46
What are the rules for deciphering "code names" such as NaCl, CO, and Cu(OH)2?

48. Bell Ringer What is an ion?
What is the electron configuration of a sulfur atom?
If an atom gains 2 electrons in a chemical compound, what is its charge?
Which element is most likely to gain electrons in a chemical reaction?
a) Ca b) Ba c) Kr d) Br