Summary
Highlights
Ionic compounds involve a metal atom transferring electrons to a non-metal atom, forming oppositely charged ions that are attracted to each other by electrostatic forces, creating an ionic bond.
Ionic compounds consist of many alternating positive and negative ions that form a three-dimensional regular lattice structure. This can be represented by diagrams using different colored spheres or ball-and-stick models.
Ionic compounds have high melting and boiling points due to the strong ionic bonds requiring significant energy to break. They can conduct electricity only when molten or dissolved in water, as this allows the charged ions to move freely.
To determine the formula of an ionic compound, the charges of the ions must balance to achieve neutrality. For example, sodium chloride (NaCl) needs one Na+ and one Cl-, while magnesium chloride (MgCl2) needs one Mg2+ and two Cl- ions.
For compounds with polyatomic ions like hydroxide (OH-) or sulfate (SO42-), their formulas and charges must be memorized. For calcium hydroxide, two hydroxide ions are needed for every one calcium ion, resulting in Ca(OH)2. For aluminium sulfate, the lowest common multiple of the charges is used, leading to Al2(SO4)3.
It's beneficial to memorize common polyatomic ions and their charges, such as nitrate (NO3-), carbonate (CO32-), and ammonium (NH4+), as this simplifies determining complex ionic compound formulas.