NTI Day 6
Naming and Writing Formulas for Covalent Compounds
Covalent compounds are compounds formed by two
elements that are NONMETAL. Nonmetals are all very
electronegative and form bonds through the sharing of
electrons to satisfy the octet rule.
Rules
1. The first element is named
first, using the elements name.
2. Second element is named as an
Anion (suffix "-ide")
3. Prefixes are used to denote the number of atoms
4. "Mono" is not used to name the first element
Note: when the addition of the Greek prefix places two vowels
adjacent to one another, the "a" (or the "o") at the end of the Greek
prefix is usually dropped; e.g., "nonaoxide" would be written as
"nonoxide", and "monooxide" would be written as "monoxide". The
"i" at the end of the prefixes "di-" and "tri-" are never dropped.
5. Anytime hydrogen bonds with a Halogen (group 17), no prefix is
needed. For example, HF, is simply hydrogen fluoride.
Some examples of writing the formula of a covalent compound.
1. Nitrogen Dioxide.
Since there is no prefix in front of nitrogen, there is only 1 nitrogen.
Since the prefix in front of oxide is di-, there are 2 oxygens.
The formula is NO2.
2. Tetracarbon monoxide.
Since the prefix in front of carbon is tetra-, there are 4 carbons.
Since the prefix in front of oxide is mono-, there is one oxygen.
The formula is C4O.
3. Diphosphorus trisulfide.
Since the prefix in front of phosphours is di, there are two phosphorus.
Since the prefix in front of sufide is tri-, there are 3 sulfurs.
The formula is P2S3.
