1. Covalent Molecules
EQ: How are the chemical formulas and chemical names written for covalent molecules?

2. Covalent Bonding Covalent bonds occur between two nonmetals.
Valence electrons are shared in a covalent bond.
A molecule is formed when two or more atoms bond covalently.

3. 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.

4. 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
When naming gases, simply use the element name and add the word gas at the end

5. Important Definitions
Chemical Formula: a representation, using symbols, showing the different types and number of atoms that make up a given compound or molecule
Subscript: small number, written behind an element, showing how many atoms of that element are found in a compound or molecule

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. What Does Naming Look Like?
1. CCl4: 2. CO: 3. NF3: 4. N2O:
Carbon tetrachloride
Carbon monoxide
Nitrogen trifluoride
Dinitrogen monoxide

8. Now, you practice Carbon dioxide CO2: ___________________________
SO2: ____________________________
S2O3: __________________________
N2O: ____________________________
PCl5: ____________________________
OF2: ___________________________
N2O4: _________________________
S4N4: ___________________________
SiCl4: __________________________
BF3: ____________________________
Sulfur dioxide
Disulfur trioxide
Dinitrogen monoxide
Phosphorous pentachloride
Oxygen difluoride
Dinitrogen tetroxide
Tetrasulfur tetranitride
Silicon tetrachloride
Boron trifluoride

9. What’s the formula? SeF6 Selenium hexafluoride: ___________
Disilicon hexabromide: __________
Diboron monosilicide: __________
Iodine pentafluoride: ________
Hexaboron monosilicide: ________
Diboron tetrabromide: _______
Diphosphorous pentoxide: ______
Carbon tetrafluoride: ________
Tetraphosphorous pentasulfide: _______
Hexasulfur monoxide: _________
Si2Br6
B2Si
IF5
B6Si
B2Br4
P2O5
CF4
P4S5
S6O

10. Lewis Structures H + O = or
Use electron-dot diagrams to show how electrons are arranged in molecules.
A dot represents a valence electron and a line represents a shared pair of valence electrons.
H2O C = + Cl or
CCl4