Apentix/AP Chemistry/Unit 2: Molecular and Ionic Compound Structure and Properties/Question
AP Chemistrymediummcq1 pt

Quartz (SiO₂) melts near 1700 degrees Celsius, dry ice (CO₂) sublimes at −78, and table salt melts at 801. Which classification explains quartz's extreme value?

A.Network covalent solid: continuous covalent bonds run throughout the crystal
B.An ionic solid with unusually small ions
C.A molecular solid with very heavy molecules
D.A metallic solid with delocalized electrons

Explanation

Core Concept

Melting a network covalent solid requires breaking covalent Si-O bonds everywhere at once, not merely separating molecules or sliding ions. Each silicon bridges to surrounding oxygens in a continuous three-dimensional framework, so enormous thermal energy precedes collapse. Molecular CO₂ only overcomes weak intermolecular attractions, and ionic NaCl only disrupts ion-ion contacts, both far cheaper processes.

Correct Answer

ANetwork covalent solid: continuous covalent bonds run throughout the crystal

More Unit 2: Molecular and Ionic Compound Structure and Properties practice questions

Try a random question →

Practice more AP Chemistry questions with full explanations

Practice Unit 2: Molecular and Ionic Compound Structure and Properties Questions →