Chapter 6: Ionic and Molecular Compounds – Study Notes for GOB Chemistry

Chapter 6: Ionic and Molecular Compounds

Introduction

This chapter introduces the foundational concepts of ionic and molecular compounds, which are essential for understanding chemical bonding and the properties of substances encountered in general, organic, and biological chemistry. Pharmacy technicians, for example, must understand these principles to safely prepare and distribute medications.

Ionic and Covalent Bonds

Formation of Chemical Bonds

Chemical bonds are formed when atoms lose, gain, or share valence electrons to achieve a stable electron configuration, typically an octet (eight valence electrons), known as the octet rule.

• Ionic bonds occur when valence electrons are transferred from a metal atom to a nonmetal atom.

• Covalent bonds form when atoms of nonmetals share valence electrons.

Example: Sodium (Na) transfers an electron to chlorine (Cl) to form NaCl (ionic bond); two hydrogen atoms share electrons to form H2 (covalent bond).

Particles and Bonds in Compounds

Types of Particles and Bonds

Compounds can be classified based on the types of particles and bonds they contain:

	Ionic Compounds	Molecular Compounds
Particles	Ions	Molecules
Bond Type	Ionic	Covalent
Examples	Na+, Cl- ions	H2O molecules, C3H8 molecules

Additional info: Ionic compounds are typically crystalline solids, while molecular compounds can be gases, liquids, or solids.

Ions: Transfer of Electrons

Formation of Ions

Atoms form ions by losing or gaining electrons:

• Cations are positively charged ions formed when atoms lose electrons (usually metals).

• Anions are negatively charged ions formed when atoms gain electrons (usually nonmetals).

Ionic bonds are the result of strong electrostatic forces between cations and anions.

Example: Na (metal) loses one electron to become Na+; Cl (nonmetal) gains one electron to become Cl-.

Ionic and Covalent Bonds: Visual Representation

Bonding Process

• When a metal (M) reacts with a nonmetal (Nm), electrons are transferred from M to Nm, forming an ionic bond.

• When two nonmetals (Nm) react, they share electrons, forming a covalent bond.

Diagram: M → Nm (transfer) = ionic bond; Nm—Nm (sharing) = covalent bond.

Key Terms and Concepts

• Octet Rule: Atoms tend to gain, lose, or share electrons to achieve eight valence electrons.

• Ionic Bond: Electrostatic attraction between oppositely charged ions.

• Covalent Bond: Sharing of electron pairs between atoms.

• Cation: Positively charged ion (e.g., Na+).

• Anion: Negatively charged ion (e.g., Cl-).

Examples and Applications

• Ionic Compound Example: Table salt (NaCl) is formed by the transfer of an electron from sodium to chlorine.

• Molecular Compound Example: Water (H2O) is formed by sharing electrons between hydrogen and oxygen atoms.

Summary Table: Ionic vs. Molecular Compounds

Property	Ionic Compounds	Molecular Compounds
Bond Type	Ionic	Covalent
Particles	Ions	Molecules
Example	NaCl	H2O

Equations and Formulas

• Ionic Bond Formation: $\text{Na} + \text{Cl} \rightarrow \text{Na}^+ + \text{Cl}^- \rightarrow \text{NaCl}$

• Covalent Bond Formation: $\text{H} + \text{H} \rightarrow \text{H}_2$

Conclusion

Understanding the differences between ionic and molecular compounds, as well as the nature of chemical bonds, is essential for further study in chemistry and for practical applications in health-related fields.