7.2 Objectives Describe the formation of ionic bonds and the structure of ionic compounds. Generalize about the strength of ionic bonds based on the physical properties of ionic compounds. Categorize ionic bond formation as exothermic or endothermic.

Oppositely charged ions attract each other, forming electrically neutral ionic compounds.

Formation of an Ionic Bond Ionic bond - electrostatic force that holds oppositely charged particles together. Compounds that contain ionic bonds are called ionic compounds.

Formation of an Ionic Bond (cont.)

Properties of Ionic Compounds Ionic compounds formed of ionic crystals. Repeating pattern of particle packing in an ionic compound.

Properties of Ionic Compounds (cont.) Crystal lattice - three-dimensional geometric arrangement of particles Responsible for the structure of many minerals.

Properties of Ionic Compounds (cont.) Melting point, boiling point, and hardness depend on the strength of the attraction.

Properties of Ionic Compounds (cont.) Two factors needed to conduct electricity: Charged particles Electrons need to be able to move freely Solid ions poor conductor of electricity Ions locked into position - electrons cannot flow freely. Liquid ions conduct electricity easily Ions free to move.

Properties of Ionic Compounds (cont.)

Energy and the Ionic Bond The energy required to separate 1 mole of ions in an ionic compound is referred to as the lattice energy. The smaller the ion, the greater the attraction.

Energy and the Ionic Bond (cont.)

Assessment Why are solid ionic compounds poor conductors of electricity? A. They are non-metals. B. They are electrolytes. C. They have electrons that cannot flow freely. D. Solids do not conduct electricity.

Assessment Why are solid ionic compounds poor conductors of electricity? C. They have electrons that cannot flow freely.

Assessment What is the electrostatic charge holding two ions together? A. covalent bond B. pseudo-noble gas bond C. crystal lattice bond D. ionic bond

Assessment What is the electrostatic charge holding two ions together? D. ionic bond