Naming and Formulas of Covalent Compounds

Composed of nonmetals located in the top right corner of the periodic table.
Held together by covalent bonds involving the sharing of electrons.
Unlike ionic compounds, covalent compounds lack charges to dictate formulas, necessitating prefixes in their names.

Prefixes indicate the specific number of each atom in a molecule.
First Element: Uses the full element name. A prefix is included only if there is more than one atom (e.g., $N_2O_3$ is dinitrogen trioxide).
Second Element: Ending is changed to $-ide$ . A prefix is always used, including $\text{mono-}$ (e.g., carbon monoxide).
Vowel Adjustment: Final vowels in prefixes are often dropped before oxygen to sound better, such as dropping the "o" in $\text{mono-}$ or the "a" in $\text{deca-}$ (e.g., $P_4O_{10}$ is tetra phosphorus deck oxide).
Common Prefixes: Includes $\text{di-}$ ( $2$ ), $\text{tetra-}$ ( $4$ ), $\text{hexa-}$ ( $6$ ), and $\text{deca-}$ ( $10$ ).

Molecules containing hydrogen do not utilize prefixes (e.g., $HI$ is hydrogen iodide).
Hydrogen-containing molecules in water follow acid naming conventions, such as hydroiodic acid.
Compounds consisting of hydrogen bonded to carbon are classified as organic molecules and use separate naming systems.

The sequence of elements in the name and formula reflects the molecular structure.
The first element named is typically the central atom and is the element furthest from fluorine on the periodic table due to its lower electronegativity.
The second element generally surrounds the central atom and is closer to fluorine (e.g., in $OF_2$ , oxygen is the central atom and is named first as oxygen difluoride).

$SCl_6$ : sulfur hexa chloride (no prefix on sulfur because it is the first element and has only one atom).
$P_4O_{10}$ : tetra phosphorus deck oxide ( $\text{tetra-}$ indicates four phosphorus atoms; $\text{deck-}$ indicates ten oxygen atoms).