Arrange the following substances in the expected order of...

Arrange the following substances in the expected order of increasing melting point: $\mathrm{KI}$, Ne, $\mathrm{K}_{2} \mathrm{SO}_{4}$ $\mathrm{C}_{3} \mathrm{H}_{8}, \mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{OH}, \mathrm{MgO}, \mathrm{CH}_{2} \mathrm{OHCHOHCH}_{2} \mathrm{OH}$.

Key Concepts

Ionic Bonding and Lattice Energy

Ionic compounds consist of oppositely charged ions arranged in a crystalline lattice. Their melting points are largely determined by the lattice energy, which is the energy required to overcome the electrostatic forces between the ions. Higher lattice energy results in significantly higher melting points compared to most molecular substances.

Intermolecular Forces

Molecular compounds do not form extended ionic lattices; instead, their melting points depend on the strength of intermolecular forces such as van der Waals interactions, dipole-dipole interactions, and hydrogen bonding. Stronger intermolecular forces result in higher melting points, while weaker forces, like those found in nonpolar or noble gas molecules, lead to lower melting points.

London Dispersion Forces

London dispersion forces are the weakest form of intermolecular attractions that occur between nonpolar molecules or noble gases. These interactions are typically very weak, which results in very low melting (and boiling) points, particularly for small atoms or nonpolar molecules.

Hydrogen Bonding

Hydrogen bonding is a particularly strong type of dipole-dipole interaction that occurs when hydrogen is bonded to highly electronegative atoms like oxygen, nitrogen, or fluorine. Compounds capable of hydrogen bonding tend to have higher melting points than those that can only engage in weaker intermolecular forces.

Transcript

Please give Ace some feedback