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BINARY COMPOUNDS

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), while examples of a binary covalent compounds include water (H₂O), and sulfur hexafluoride (SF₆).

Corresponding to the two limiting types of element, metal and nonmetal, there are three limiting types of binary compound:

o Metallic These are formed principally by the combination of a metal with a metal, and have the characteristics of a metal.

o Nonmetallic These are formed principally by the combination of a nonmetal with a nonmetal, and have the characteristics of a nonmetal.

o Salt-like These are formed principally by the combination of a metal with a nonmetal, and constitute a new class of material.

In the formula for a binary compound, the element that attracts electrons less is usually written first. The elements are assigned an electronegativity that reflects their affinity for electrons in chemical bonds. The elements that attract electrons most are said to have the highest electronegativities or to be the most electronegative. Fluorine, the most electronegative element, is assigned an electronegativity of 4.0, and the other elements have values relative to that of fluorine. The elements that attract electrons least are said to have the lowest electronegativities or to be the most electropositive.

Binary compounds naming rules.

1. The Cation (positive ion) is named first, the Anion second.

2. Monoatomic Cations take the element name

Na⁺ → Sodium

Ca²⁺ → Calcium

3. Monoatomic Anions take the elements name and ends with "-ide"

Cl^- → Chloride

NaCl → Sodium Chloride

Li₃N → Lithium Nitride

Common Prefixes for Binary Covalent Compounds

Binary acids

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 7^th 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.

An example is HCl: hydrogen chloride.