Naming and Drawing Ionic Molecules

Introduction

Ionic compounds are formed when metals transfer electrons to nonmetals, resulting in the formation of positively charged cations and negatively charged anions. This lesson focuses on the rules for naming and drawing ionic molecules.

Naming Ionic Compounds

1. Identify the Cation and Anion:

   • The cation is usually a metal (e.g., $Na^{+}$ for sodium).
   • The anion is usually a nonmetal (e.g., $Cl^{-}$ for chloride).

2. Naming Rules:

   • Name the cation first, followed by the anion.
   • For anions, change the ending of the element's name to “-ide” (e.g., $Cl$ becomes $Cl^{-}$ -> chloride).
   • For transition metals, indicate the charge with Roman numerals (e.g., $Fe^{2+}$ is iron(II)).

3. Examples:

   • $NaCl$ is named sodium chloride.
   • $FeCl_{2}$ is named iron(II) chloride.

Drawing Ionic Compounds

1. Determine the Formula:

   • Use the charges of the cation and anion to determine the ratio in which they combine (e.g., ${Na}^{+} + {Cl}^{-} \rightarrow {NaCl}$).

2. Draw the Structure:

   • Represent the cation and anion with their respective symbols.
   • Show the transfer of electrons if desired (e.g., an arrow from metal to nonmetal).

Key Questions

• What is the difference between a cation and an anion?
• How do you determine the charge of a transition metal in a compound?
• Why do we change the ending of an anion to “-ide”?

Summary

Understanding the principles of naming and drawing ionic compounds is fundamental in chemistry, as it lays the groundwork for further studies in chemical bonding and reactions.