The key difference between ionic and metallic solids is that the ionic solids essentially contain cations and anions, whereas the metallic solids contain metal atoms and free electrons.
Both ionic solids and metallic solids are in a solid-state. But they are different from each other in composition as well as properties.
CONTENTS
1. Overview and Key Difference
2. What are Ionic Solids
3. What are Metallic Solids
4. Side by Side Comparison – Ionic vs Metallic Solids in Tabular Form
5. Summary
What are Ionic Solids?
Ionic solids are chemical compounds containing cations and anions. These ions are held together by electrostatic forces. We name these forces as ionic bonds. The ions bind with each other in a way that the overall compound is neutral (no negative or positive charge). Here, the number of cations surrounding an anion and vice versa can differ from one solid to another depending on the charge of cation and anion.
Figure 01: Strong Crystalline Structure of Ionic Solids
The ions in the solid can be simple ions such as sodium ions and chloride ions (in sodium chloride ionic compound or salt), or there can be complex ions such as polyatomic ions, i.e. ammonium ion. These solids exist as three-dimensional networks, and usually, they have a crystalline structure.
Furthermore, the ionic solids containing hydrogen ions are acids, and those containing hydroxide ions are bases. Ionic solids containing none of these ions are termed as salts. Salt compounds form from acid-base reactions. Besides, ionic solids may also form from evaporation (removing the solvent will crystallize the ions into a solid), precipitation, solid-state reactions, etc.
Usually, ionic solids have very high melting and boiling points because they have a strong 3D network structure which is very difficult to break down. These solids are also typically hard and brittle. Moreover, these ionic solids are electrically insulating, but when molten or dissolved, they become highly conductive because the ions are released.
What are Metallic Solids?
Metallic solids are solid compounds containing metal atoms and electrons around them. Metals are good examples of metallic solids. The metal atoms of these solids are held together via metallic bonds. Metal atoms exist as cations having a positive electrical charge, and these atoms are immersed in a sea of electrons. These electrons come from the metal atoms during the formation of cations.
Figure 02: Gallium Metal in Solid State
This means, the metal atoms form cations by releasing valence electrons and these electrons occur around the metal ion in a delocalized state, and these electrons cause the metal atoms to be held together.
What is the Difference Between Ionic and Metallic Solids?
Both ionic solids and metallic solids are in the solid-state, but they are different from each other in the composition and properties. The key difference between ionic and metallic solids is that ionic solids essentially contain cations and anions, whereas metallic solids contain metal atoms and free electrons.
Moreover, the ionic solids have electrostatic attraction forces between cations and anions, while the metallic solids have metallic bonds. When considering the properties, ionic solids are hard and brittle while metallic solids are hard, ductile and malleable.
The below infographic summarizes the difference between ionic and metallic solids.
Summary – Ionic vs Metallic Solids
Both ionic solids and metallic solids are in the solid-state, but they are different from each other in their composition, which also results in their different properties. The key difference between ionic and metallic solids is that ionic solids essentially contain cations and anions, whereas metallic solids contain metal atoms and free electrons. Besides, the ionic solids have electrostatic attraction forces between cations and anions but, in metallic solids, there are metallic bonds.
Reference:
1. “Ionic Solids.” Chemistry LibreTexts, Libretexts, 5 June 2019, Available here.
Image Courtesy:
1. “Gallium crystals” By en:user:foobar – Own work (CC BY-SA 3.0) via Commons Wikimedia
2. “Potassium-chloride-3D-ionic” By Benjah-bmm27 – Own work (Public Domain) via Commons Wikimedia