CHEM1201 Lecture Notes - Lecture 23: Phase Transition, Covalent Bond, Heat Capacity

• School: Flinders University
• Department: CHEM Chemistry
• Course: CHEM1201
• Professor: Sue Pyke

Document Summary

Solids: very strong intermolecular forces > thermal movement. Molecules held together by intermolecular forces (mostly induced dipole-induced dipole, dipole-induced dipole, dipole-dipole and h-bonds) in a regular array individual molecules can be recognised in the lattice low melting points (but depends on compound) Examples: all molecular co(cid:373)pou(cid:374)ds, if they wa(cid:374)t to crystallise. Highly regular structure, in 3 dimensions intermolecular interaction in the form of hydrogen bonding (when they melt, these bonds between molecules are broken) Held together by electrostatic attraction between ions strong forces, high temperatures required for melting regular array of positive and negative ions. Patterns other than depicted here are also possible. Different bonds: covalent (covalent network, held together by covalent bonds, high melting points, nonbonding, held together by dispersion forces low melting points, metallic, held together by metallic bonds, variable melting points. Hfus > 0 (endothermic: heat energy involved on freezing = molar enthalpy of crystallisation = - As melting point increases h .