1. Covalent Structures
EQ: How are the chemical formulas and chemical names written for covalent molecules?
How do you draw VSEPR diagrams for covalent compounds? What are the names and bonding/lone pairs for each molecular shape?

2. Ionic Bonding
Ionic bonds occur between a metal and a nonmetal, or between a positively charged particle(cation) and a negatively charged particle (anion).
Ionic bonds involve a transfer of electrons.
Can you identify which of the following are joined by ionic bonds?
NaCl - K3N MgBr2
CO2 - N Al2O3

3. Covalent Bonding Covalent bonds occur between two nonmetals.
A molecule is formed when two or more atoms bond covalently.
Covalent bonds involve sharing of electrons.

4. Diatomic Molecules
Certain elements occur in nature as diatomic molecules and not as single atoms (more stable as the molecule)
Examples:
H2, N2, O2,
F2, Cl2, Br2, I2
Diatomic Molecules
are bonded together
by covalent bonds.

5. Naming Molecular Compounds
The first element written in the formula is always written first, using the element name.
The second element is named using the root of the element and the suffix “-ide”.
Prefixes are used to indicate the number of atoms of each type that are present in the compound.
Exception: Do not use the prefix mono- for the first element
Drop the final letter of the prefix when the element name begins with a vowel
Common Names: Ozone O3, Methane CH4, Hydrogen peroxides H2O2, Water H2O, Ammonia NH3

6. Table 1: Common Prefixes Used in Covalent Compounds
Number of atoms
Prefix 1
Mono- 6
Hexa- 2
Di- 7
Hepta- 3
Tri- 8
Octa- 4
Tetra- 9
Nona- 5
Penta- 10
Deca-

7. Covalent Names Common Names: Ozone O3 Methane CH4
Hydrogen peroxides H2O2
Water H2O
Ammonia NH3

8. Naming Carbon dioxide CO2: ________________________________
SO2: ________________________________
S2O3: _______________________________
N2O: _______________________________
PCl5: ________________________________
Sulfur dioxide
Disulfur trioxide
Dinitrogen monoxide
Phosphorous pentachloride

9. Formula Writing Selenium hexafluoride: ___________
Disilicon hexabromide: __________
Diboron monosilicide: __________
Iodine pentafluoride: ________
Hexaboron monosilicide: ________
SeF6
Si2Br6
B2Si
IF5
B6Si

10. Drawing VSEPR
Examples
CO2
BF3
3. CH4
4. NH3
5. H2O
Determine the total number of valence electrons for the compound.
Note: Neg/Pos charge will change # electrons
Ex: NO3-
Choose a central atom (least electronegative) and surround with remaining atoms as outer atoms.
H, F, Br, Cl, and I are outer atoms
Connect central atom to outer atoms w/a single bond (2 electrons/shared pair) & subtract electrons used
Place remaining electrons on outer elements to fill valence shell, any remaining electrons will be placed on the central atom.
Make double/triple bonds if necessary
All atoms (except H) prefer to have 8 valence e-.
Exceptions to this rule are:
B – electron deficient, typically only has 6 e–
P – can have 10 e– (in compounds such as PCl5)
S – can have up to 12 e– (in compounds such as SF6)

11. Bonds Single: Double: Triple : Consists of 1 sigma bond Weakest bond
Longest bond
Double:
Consists of 1 sigma and 1 pi bond
Triple :
Consists of 1 sigma and 2 pi bonds
Strongest bond
Shortest length

14. Polarity Polar: “opposite ends” Nonpolar: “same ends”
Ionic compounds: Positive & Negative ends
Polar Covalent: Partially Positive & Negative ends
Unequal sharing of electrons = Dipole
Ex: H2O
Nonpolar: “same ends”
Nonpolar Covalent:
equal sharing of electrons
Dipole moments cancel out
Ex: CO2

15. Resonance structures:
Bracket the structure [ ]
Indicates resonant bonds with dotted line
Polyatomic Ions:
Indicate charge top right exterior of bracket

16. Practice Problems: Draw and Identify
CO32-
SiS2
OF2

17. Practice Problems: Draw and Identify
PCl3
NH4+
CH3Cl
SCl2

18. Homework Check 8. Nitrogen trifluoride_______
9. calcium phosphate_______
10. Phosphoric acid________
11. aluminum phosphide____
12. iron(III) sulfide_____
13. diphosphorus trioxide___
1. HNO2___________________ 2. KClO2 ___________________ 3. FeCl2___________________ 4. PCl3____________________ 5. H2S_____________________ 6. K3PO3___________________ 7. SO3______________________