4: Ionic Bonding and Simple Ionic Compounds
- Page ID
- 469220
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There are only 118 known chemical elements but tens of millions of known chemical compounds. Compounds can be very complex combinations of atoms, but many important compounds are fairly simple. Table salt, as we have seen, consists of only two elements: sodium and chlorine. Nevertheless, the compound has properties completely different from either elemental sodium (a chemically reactive metal) or elemental chlorine (a poisonous, green gas). We will see additional examples of such differences in this chapter as we consider how atoms combine to form compounds.
- 4.0: Prelude to Ionic Bonding and Simple Ionic Compounds
- We will see that the word salt has a specific meaning in chemistry, but to most people, this word refers to table salt. This kind of salt is used as a condiment throughout the world, but it was not always so abundant. Two thousand years ago, Roman soldiers received part of their pay as salt, which explains why the words salt and salary come from the same Latin root (salarium). Today, table salt is either mined or obtained from the evaporation of saltwater.
- 4.1: Two Types of Bonding
- Atoms have a tendency to have eight electrons in their valence shell. The attraction of oppositely charged ions is what makes ionic bonds.
- 4.2: Ions
- Ions can be positively charged or negatively charged. A Lewis diagram is used to show how electrons are transferred to make ions and ionic compounds.
- 4.3: Formulas of Ionic Compounds
- Although ionic compounds are made up of ions with charges, the overall charge must be zero, because matter is electrically neutral. Therefore, proper chemical formulas for ionic compounds can be determined by balancing the total positive charge with the total negative charge.
- 4.4: Naming Ionic Compounds
- Each ionic compound has its own unique name that comes from the names of the ions that make up the formula unit. By convention, the cation is always named first followed by the anion. Because the ratio of ions in a compound is determined by the charge on each ion, no prefixes are needed to indicate how many of each ion are present. When a compound contains an ion with variable charge, a Roman numeral is used to specify the charge.
- 4.5: Formula Mass
- Formula masses of ionic compounds can be determined from the masses of the atoms in their formulas.
- 4.6: Some Properties of Ionic Compounds
- Ionic compounds are composed of cations and anions that are strongly attracted to each other. Hence, ionic solids have very high melting points and are extremely hard. When dissolved in water, the ions separate from each other, allowing them to form electrolyte solutions.
- 4.7: H⁺ and OH⁻ Ions - An Introduction to Acids and Bases
- Hydrogen ions (H+) and hydroxide ions (OH–) are two important ions discussed later in this text as acidic and basic ions respectively. Both of these ions can form compounds that you will see in organic and biological chemistry.
- 4.E: Ionic Bonding and Simple Ionic Compounds (Exercises)
- These are homework exercises to accompany Chapter 3 of the Ball et al. "The Basics of GOB Chemistry" Textmap.
- 4.S: Ionic Bonding and Simple Ionic Compounds (Summary)
- To ensure that you understand the material in this chapter, you should review the meanings of the following bold terms and ask yourself how they relate to the topics in the chapter.