Covalent & Molecular Compound
Core Concept
Covalent compounds are substances formed by the sharing of electrons between nonmetals. Unlike ionic compounds, which involve the transfer of electrons, covalent compounds consist of molecules held together by strong covalent bonds.
Memorize the Prefixes: Knowing the prefixes makes it easy to determine the number of atoms.
Check for Mono- Prefix: Only use “mono-” for the second element if there's only one atom of that element.
Remember -ide Ending: The second element should always end with “-ide.”
Test Yourself
Podcast Episode
Practice Problems & Worked Out Examples 🔒
Naming Covalent Compounds
Use prefixes to indicate the number of atoms for each element.
The first element keeps its full elemental name.
The second element takes its root name and ends with "-ide."
Omit "mono-" for the first element if there’s only one atom.
Examples:
CO: Carbon monoxide (not monocarbon monoxide)
CO₂: Carbon dioxide
PCl₅: Phosphorus pentachloride
N₂O₄: Dinitrogen tetroxide
Write Formula of Covalent Compounds
Identify the elements in the compound.
Use prefixes to determine the number of atoms for each element.
Write the formula by listing the elements and using subscripts to show the number of atoms for each element (based on the prefixes).
Example:
Dinitrogen trioxide: The prefix "di-" indicates two nitrogen atoms (N₂), and "tri-" indicates three oxygen atoms (O₃), so the formula is N₂O₃.
It is important to note that when writing the formula, the prefixes are not included for the first element if there is only one atom of that element. However, if there is more than one atom of the first element, the prefix "mono-" is used. The prefixes are always included for the second element.
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