A binary compound is a chemical compound that contains exactly two different elements. Examples of binary ionic compounds include calcium chloride (CaCl2), sodium fluoride (NaF), and magnesium oxide (MgO), whilst examples of a binary covalent compounds include water (H2O), and sulfur hexafluoride (SF6).
In the group of binary compounds of hydrogen a binary acid will include a hydrogen atom attached to another atom that will typically be in the 17th group of the periodic Table. These include chlorine, fluorine, bromine, iodine, and astatine. Others such as sulfur, tellurium, polonium, selenium, and arsenic are also included.
The naming convention is:
“Hydro-” + Nonmetal + “-ic” + “acid”
An example is HCl: hydrochloric acid.
If the acid is in a gaseous form or an anhydrous form, the "-ic" is replaced by "-ide" and the "acid" suffix is removed.
Binary covalent compounds
Nonmetal X + Nonmetal Y + "-ide."
Add the appropriate Latin prefix to each element name to denote the number of atoms of each element present in a molecule of the compound. This method is generally not used with ionic compounds (see below). For example, K2O is usually not called dipotassium monoxide; it is simply potassium oxide. The reason that it is called potassium oxide is that potassium oxide is a binary ionic compound, thus it follows the rules for binary ionic compounds. P4O6, however, would be tetraphosphorus hexoxide. Some elements beginning with vowels (Oxygen, for example) replace the vowel ending of its prefix; mono- + Oxide = Monoxide, O4 = Tetroxide, O5 = Pentoxide, and so on.
Binary ionic compounds
A binary ionic compound is a salt consisting of only two elements in which both elements are ions, a cation (which has a positive charge) and an anion (which has a negative charge). When naming these compounds, its composition must be considered. Type 1 binary ionic compounds are those in which the cation has only one form, or charge. Type 2 binary ionic compounds are those in which the cation can have multiple forms.
1. The cation (which is a metal in most cases) is listed first and the anion (which is a nonmetal in most cases) second. 2. The cation takes the name of its elemental form. For example, Li+ would be called "Lithium". 3. The anion name uses the first part of its elemental name, and subsequently adding the suffix "-ide". For example, Br- would be called "Bromide" .Examples: LiF (which is composed of Li+ cation and F− anion) = lithium fluoride BaO (which is composed of Ba2+ cation and O2- anion) = barium oxide.
Metals used are transition metals except for Al3+, Zn2+, Ag+. 1. The steps follow those of Type 1 Binary Ionic compounds however, since the cation can take on multiple charges, the charge must be written within parentheses in Roman numerals after stating the cation name. Examples: CoO (which is composed of Co²+ cation and O²- anion) = cobalt(II) oxide FeN (which is composed of Fe³+ cation and N³- anion) = iron(III) nitride
Note that there is another way to name Type 2 ionic compounds that is not as common. This involves using an alternate, Latin name for the cation. Common Type 2 cation include Iron, Copper, Cobalt, Tin, Lead, and Mercury.
When naming binary compounds with polyatomic ions: 1. The cation is listed first and the anion second. 2. The polyatomic ion names must be memorized. 3. No extra suffixes are added. Examples: NaCN (which is composed of Na+ cation and CN- polyatomic anion) = sodium cyanide; NH4Cl (which is composed of NH4+ polyatomic cation and Cl- anion) = ammonium chloride
When multiple compounds are possible, the oxidation state of the cation is added after it in Roman numerals (copper(II) sulfide), or the cation's stem is used with a -ous or -ic suffix (cupric sulfide).