6.2: Ionic Compounds

Ionic Compound

A compound formed by the transfer of electrons from a metal to a nonmetal, resulting in the formation of positive and negative ions held together by ionic bonds.

Properties of Ionic Compounds

The physical and chemical characteristics of ionic compounds differ significantly from those of the original elements due to the formation of positive and negative ions and the strong attractions between them.

Crystal Structure of NaCl

In a crystal of NaCl, the larger Cl^- ions are arranged in a three-dimensional structure with smaller Na^+ ions occupying the spaces between them, leading to strong attractions between ions and high melting points.

Chemical Formulas of Ionic Compounds

The chemical formula of an ionic compound represents the lowest whole-number ratio of ions, ensuring charge balance where the total positive charge equals the total negative charge.

Subscripts in Formulas

Subscripts in ionic compound formulas indicate the number of ions needed for charge balance, as seen in compounds like MgCl2 where the subscript 2 shows the requirement for two Cl^- ions to balance the charge of Mg^+2.

Writing Ionic Formulas

Ionic compound formulas are written based on the charges of the ions involved, ensuring overall charge neutrality by pairing cations with anions in the lowest ratio, known as a formula unit.