8.2 Ionic Bonds and Ionic Compounds http://www.ck12.org Contents
8.2 Ionic Bonds and Ionic Compounds
Lesson Objectives
- Explain how an ionic bond is formed when electrons are transferred from one atom to another in terms of the
resulting electrostatic attraction. Draw diagrams showing this process. - Describe the structural arrangements of ions in a crystal, including coordination number and its relationship
to a given compound’s formula unit. - Explain how various physical properties result from the ionic crystal lattice, such as strength, hardness, high
melting points, brittleness, and electrical conductivity.
Lesson Vocabulary
- coordination number
- formula unit
- ionic bond
- ionic compound
Check Your Understanding
Recalling Prior Knowledge
- What types of charged particles attract each other and what types repel each other?
- How is an empirical formula different from a molecular formula?
- What is a crystal lattice?
Most of the rocks and minerals that make up the Earth’s crust are composed of positive and negative ions held
together by ionic bonding. Anionic compoundis an electrically neutral compound consisting of positive and
negative ions. You are very familiar with some ionic compounds, such as sodium chloride (NaCl). A sodium
chloride crystal contains equal numbers of positive sodium ions (Na+) and negative chloride ions (Cl−).
Ionic Bonds
Oppositely charged particles attract each other. This attractive force is often referred to as an electrostatic force. An
ionic bondis the electrostatic force that holds ions together in an ionic compound. The strength of an ionic bond is
directly dependent upon the magnitudes of the charges and inversely dependent on the distance between the charged
particles. For example, a cation with a 2+ charge will make a stronger ionic bond than a cation with a 1+ charge.