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11.10: Naming Compounds

  • Page ID
    476596
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    Learning Objectives
    • Correctly name a covalent compound.

    We have discussed many kinds of compounds and the bonds that hold them together. The rules for naming ionic compounds are a bit involved, so we won't cover them in this text. Instead we will focus only on the methods to name covalent compounds.

    To name simple covalent compounds, follow these rules:

    • Start with the name of the element closer to the left side of the periodic table.
    • Follow this with the name of element closer to the right of the periodic table. Give this second name the suffix –ide.
    • Use prefixes to represent the numbers of the different atoms in each molecule of the compound. The most commonly used prefixes are shown in the Table below.

    Table \(\PageIndex{1}\)

    Naming and Writing Formulas for Covalent Compounds
    Number Prefix
    1 mono- (or none)
    2 di-
    3 tri-
    4 tetra-
    5 penta-
    6 hexa-
    Exercise \(\PageIndex{1}\)

    What is the name of the compound that contains three oxygen atoms and two nitrogen atoms?

    Answer

    The compound is named dinitrogen trioxide. Nitrogen is named first because it is farther to the left in the periodic table than oxygen. Oxygen is given the -ide suffix because it is the second element named in the compound. The prefix di- is added to nitrogen to show that there are two atoms of nitrogen in each molecule of the compound. The prefix tri- is added to oxygen to show that there are three atoms of oxygen in each molecule.

    In the chemical formula for a covalent compound, the numbers of the different atoms in a molecule are represented by subscripts. For example, the formula for the compound named carbon dioxide is CO2.

    Exercise \(\PageIndex{2}\)

    What is the chemical formula for dinitrogen trioxide?

    Answer

    The chemical formula is N2O3.

    Section Summary

    • A few rules can be applied to name simple covalent compounds: name the left-most element in the periodic table first, add -ide to the second named element, and use prefixes for the numbers of atoms.

    This page titled 11.10: Naming Compounds is shared under a CC BY-NC-SA license and was authored, remixed, and/or curated by Jamie MacArthur via source content that was edited to the style and standards of the LibreTexts platform.