Covalent Network Solids: Structure, Properties, and Examples in Chemistry

📚 Quick Study Guide

⚛️ Definition: Covalent network solids are substances where atoms are held together in a giant network or lattice entirely by covalent bonds. 💎 Structure: These solids have extended networks with no discrete molecules. Think of them as one giant molecule. 🌡️ Melting Point: Generally, they have very high melting and boiling points due to the strong covalent bonds that need to be broken. 🔨 Hardness: Typically very hard because of the strong, directional covalent bonds. ⚡ Conductivity: Most are poor conductors of electricity, but some exceptions exist (e.g., graphite). 🧪 Examples: Diamond ($C$), Quartz ($SiO_2$), Silicon Carbide ($SiC$). ➗ Key Properties: Hardness, high melting point, poor conductivity (usually), insolubility in common solvents.

🧪 Practice Quiz

1. Which of the following is a characteristic of covalent network solids?
   1. High vapor pressure
   2. Low melting point
   3. Excellent electrical conductivity
   4. High hardness
2. Which of the following substances is an example of a covalent network solid?
   1. $NaCl$
   2. $CO_2$
   3. $SiO_2$
   4. $H_2O$
3. What type of bonding holds atoms together in a covalent network solid?
   1. Ionic bonds
   2. Metallic bonds
   3. Covalent bonds
   4. Hydrogen bonds
4. Why do covalent network solids typically have high melting points?
   1. Weak intermolecular forces
   2. Strong covalent bonds throughout the network
   3. Presence of delocalized electrons
   4. Low molecular weight
5. Which property is NOT typically associated with covalent network solids?
   1. High melting point
   2. Extreme hardness
   3. Good electrical conductivity
   4. Insolubility in water
6. Which of the following best describes the structure of a covalent network solid?
   1. Discrete molecules held together by weak forces
   2. A lattice of ions
   3. A giant network of atoms held together by covalent bonds
   4. Atoms arranged in a metallic lattice
7. Silicon carbide ($SiC$) is used in high-temperature applications. Which property makes it suitable for this purpose?
   1. Low density
   2. High electrical conductivity
   3. High melting point
   4. Solubility in water