Question

Rank each substance above from strongest to weakest intermolecular force. Do not look up these substances' physical properties...determine the ranking based on general intermolecular force principles. If you predict an "anomaly" (i.e. a "LDF only" molecule with greater intermolecular forces than a dipole-dipole or hydrogen bonding molecule), you must briefly state your reasoning. Please justify why you put each molecule in its order.

CCl₄   BH₃   SF₄ CH₃NH₂   CO₂ N₂O (NNO) CH₃OH

Answer 1

sf4 > ch3n2 > no2 > co2 > ch3oh > bh3 > ccl\

The strongest intermolecular force is Hydrogen Bonding! Hydrogen atoms have a very strong attraction to Fluorine, Oxygen, and Nitrogen atoms, a molecule with Hydrogen and a molecule with F, O, or N will form strong hydrogen bonds. Just remember FON or NOF.

The second strongest is dipole-dipole attraction. Some molecules are polar, meaning they have a positive and negative pole, kind of like magnets. And just like magnets, two polar molecules attract because one's negative pole is attracted to the other's positive pole.

The weakest of them all is London Dispersion force. This force exists between all molecules, no matter what atoms are in them. Basically, as electrons fly around the nuclei of atoms, they'll often create a very weak dipole that exists only for a tiny fraction of a second. Basically these LD forces are just like D-D forces except weaker.