Ionic Compound Properties

Overview

This lecture covers the four main properties of ionic compounds, using table salt as a common example, and explains why these properties occur.

Ionic compounds are solids at room temperature (about 25°C) due to strong electrostatic attraction between ions.
They form a crystal structure, with a repeating pattern of cations and anions, often cubic like sodium chloride (table salt).
Ionic compounds have high melting and boiling points because a lot of energy is required to separate the strongly attracted ions.
Table salt has a melting point around 800°C (1500°F), much higher than typical ovens can reach.
Ionic compounds are brittle and fracture along straight edges due to their regular crystal lattice.
When hit, ionic compounds cleave easily because of the specific arrangement of ions.
They conduct electricity only when melted or dissolved in water, as ions become free to move and carry charge.

When ionic compounds dissolve in water, ions separate and are surrounded by water molecules.
Electricity requires moving electrons, which can "ride" on the free-moving charged ions in solution or liquid state.
Solid ionic compounds do not conduct electricity because ions are fixed in place; only liquids and solutions allow conductivity.

Ionic Compound — a chemical compound composed of positively (cations) and negatively (anions) charged ions held together by electrostatic forces.
Electrostatic Attraction — force that holds oppositely charged ions together in ionic compounds.
Crystal Structure — a repeating, ordered arrangement of ions in a solid.
Brittle — a material property where substances break or shatter easily without bending.
Conduct Electricity — the ability to allow electrons or ions to move and transmit electrical current.