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chlorine and fluorine Molecular Compounds

Experiment Naming Ionic and Molecular Compounds

Naming Ionic Compounds

Ionic compounds are chemical compounds containing both a cation (positive ion) and an anion (negative ion) held together by electrostatic forces, also known as ionic bonds. Ionic compounds are different from molecular compounds in that they usually contain a metal or an ammonium ion (NH4

+) and molecular compounds are composed of nonmetals. A binary ionic compound contains two elements, one metal and one nonmetal.

To name a binary ionic compound, the cation elemental name is listed first, followed by the root of the anion ending in “-ide.” For example:

● NaCl = sodium chloride

Greek prefixes are not used in naming the number of atoms of each element for ionic compounds. For example:

● Li3N = lithium nitride, NOT trilithium nitride.

Ionic compounds are written as neutral compounds, meaning the overall charge of the compound must equal zero. In order to determine the overall charge, the oxidation state of the metal and nonmetal must be known in order to ensure the correct number of atoms of each element are present in the compound. The oxidation state represents the number of electrons that an atom can gain, lose, or share when bonded with an atom of another element. The oxidation state for each element can be found on the periodic table in Figure 1. We will discuss how to use the oxidation state to calculate the number of atoms of a compound in further detail later.

Converting an Ionic Compound Formula to a Name

1. Use the periodic table to determine if a metal is present in the compound.

Note: Be aware that many elements have similar names and symbols.

a. If a metal is present, the compound is likely an ionic compound.

2. Determine if the metal ion (cation) has a “fixed charge.” A fixed charge means that there is only one possible oxidation state, as shown in Figure 3. Cations with a fixed charge include.

a. All elements in Group IA and Group IIA

b. Al3+

c. Transition metals with a fixed charge: Ag1+, Zn2+, and Cd2+