1. Naming Covalent (Molecular) Compounds

2. Properties of Covalently Bonded Compounds
Usually TWO NONMETALS bonded together
Two nonmetals share electrons between them
Can be Gases, Liquids or “squishy” solids.
Generally have LOW melting and boiling points
Do not conduct electricity well
Usually not very soluble in water

3. How are covalent compounds different than Ionic ones?
Metal – Nonmetal bond
Electrons are transferred
Generally solid
High Melting/Boiling pts
Conduct electricity when melted or dissolved
Nonmetal-Nonmetal bond
Electrons are shared
Solid, Liquid or gas
Low Melting/Boiling pts
Do not conduct

4. What is the basic structural unit of a covalent compound?
Covalent compounds form MOLECULES
Bonding between atoms in a molecule is generally much, much stronger than the attraction between different molecules.
Married couples analogy…

5. How are covalent compounds different than Ionic ones?
Basic Structural unit is the “Unit cell” or the “formula unit”
Ions arranged in crystal structure
Basic structural unit is the MOLECULE
Molecules may attract each other but that attraction is small compared with internal bonding

6. Naming molecules from their formulas
CO2
N2O
B2H6
CH4
NH3
Use the Prefixes…
1 – mono
2 – Di
3 – Tri
4 – Tetr(a)
5 – Pent(a)
6 – Hex(a)
7 – Hept(a)
8 – Oct(a)
9 – Non(a)
10 – Dec(a)

7. Naming molecules from their formulas
CO carbon dioxide
N2O dinitrogen monoxide
B2H6 diboron hexahydride
CH4 carbon tetrahydride
commonly known as “Methane”
NH3 nitrogen trihydride
commonly known as “Ammonia”
Use the Prefixes…
1 – mono
2 – Di
3 – Tri
4 – Tetr(a)
5 – Pent(a)
6 – Hex(a)
7 – Hept(a)
8 – Oct(a)
9 – Non(a)
10 – Dec(a)

8. Writing formulas for molecules from their names
Carbon monoxide
Sulfur trioxide
Silicon tetrachloride
Diphosphorus pentachloride
Tetraphosphorus triselenide
Writing formulas for molecules from their names
Use the Prefixes…
1 – mono
2 – Di
3 – Tri
4 – Tetr(a)
5 – Pent(a)
6 – Hex(a)
7 – Hept(a)
8 – Oct(a)
9 – Non(a)
10 – Dec(a)

9. Writing formulas for molecules from their names
Carbon monoxide CO
Sulfur trioxide
SO3
Silicon tetrachloride
SiCl4
Diphosphorus pentachloride
P2Cl5
Tetraphosphorus triselenide
P4Se3
Use the Prefixes…
1 – mono
2 – Di
3 – Tri
4 – Tetr(a)
5 – Pent(a)
6 – Hex(a)
7 – Hept(a)
8 – Oct(a)
9 – Non(a)
10 – Dec(a)

10. Practice naming and writing formulas
WARNING! Some of the compounds listed below are NOT covalent. Make sure you don’t use prefixes when naming them.
Name these compounds: CBr4 , N2O5, MgF2 , SeS ,
Write formulas for these: Carbon disulfide, Disilicon hexahydride, Potassium carbonate, Dinitrogen tetroxide
Practice naming and writing formulas
Use the Prefixes…
1 – mono
2 – Di
3 – Tri
4 – Tetr(a)
5 – Pent(a)
6 – Hex(a)
7 – Hept(a)
8 – Oct(a)
9 – Non(a)
10 – Dec(a)