1. Presence of Nonmetals: Molecular compounds are typically formed between two or more nonmetals.
* Examples: CO2 (carbon dioxide), H2O (water), NH3 (ammonia), CH4 (methane)
2. Use of Prefixes: Molecular compounds often use prefixes to indicate the number of each type of atom in the compound. These prefixes are:
* Mono - 1
* Di - 2
* Tri - 3
* Tetra - 4
* Penta - 5
* Hexa - 6
* Hepta - 7
* Octa - 8
* Nona - 9
* Deca - 10
* Examples: CO2 (carbon dioxide), N2O4 (dinitrogen tetraoxide), PCl5 (phosphorus pentachloride)
3. Specific Chemical Properties:
* Molecular compounds tend to have lower melting and boiling points than ionic compounds.
* They are generally poor conductors of electricity in both solid and liquid states.
Important Notes:
* Exceptions: There are a few exceptions to these rules. For instance, some compounds containing a metal and a nonmetal can also be molecular compounds.
* Context: It's crucial to consider the context when determining if a compound is molecular. For example, if a formula represents a specific molecule, like water (H2O), it is definitely a molecular compound.
In summary, you can usually recognize a molecular compound by looking for a formula containing only nonmetals and prefixes indicating the number of each type of atom.
