Molecular Polarity and Intermolecular Forces Flashcards

Vocabulary flashcards covering molecular shapes, bond angles, polarity, intermolecular forces, and solubility rules.

Polar Molecule

A molecule with an uneven distribution of electrons that forms a positive pole and a negative pole, such as $H_2O$

Nonpolar Molecule

A molecule with an even distribution of electrons across its structure, leaving no positive or negative poles, such as $CH_4$

Dipole Moment of Water

The net electric dipole moment of $H_2O$ ($\boldsymbol{\nu}_{H_2O} = 1.85\,D$), resulting from the vector sum of polar $O-H$ bond dipoles towards oxygen

"Like Dissolves Like" Rule

A principle stating that solutes dissolve in solvents with similar polarity because they experience similar intermolecular forces (IMFs)

Ion-Dipole Force

The strongest intermolecular force present when an ionic compound dissolves in a polar solvent, drawing cations to the negative pole and anions to the positive pole

London Dispersion Forces (LDF)

Weak intermolecular forces caused by temporary fluctuations in electron density, present in all molecules and the only IMF between nonpolar substances

Soap Molecule Structure

A structure featuring a long nonpolar hydrophobic tail that experiences LDF with nonpolar substances and a polar hydrophilic head that experiences dipole-dipole forces with water

Phosphite Ion ($PO_3^{3-}$)

A polar polyatomic ion with a trigonal pyramidal shape, bond angles of $<109.5^\circ$, and high solubility in water

Sulfur Trioxide ($SO_3$)

A nonpolar molecule with a trigonal planar geometry, bond angles of $120^\circ$, and no solubility in water

Carbon Dioxide ($CO_2$)

A nonpolar linear molecule with double bonds between carbon and oxygen, featuring a bond angle of $180^\circ$

Chloromethane Polar Bond

In $CH_3Cl$, the $C-Cl$ bond is the most polar bond due to fluorine/chlorine high electronegativity compared to carbon and hydrogen

IMF Strength Ranking

The ranking of intermolecular forces from weakest to strongest: LDF < dipole-dipole forces < hydrogen bonding < ion-dipole forces

Linear Shape (2 bonded, 0 lone pairs)

A molecular geometry with 2 atoms bonded to a central atom and 0 lone pairs, giving a bond angle of $180^\circ$

Bent Shape (2 bonded, 1 lone pair)

A molecular geometry with 2 atoms bonded to a central atom and 1 lone pair, creating a bond angle of $<120^\circ$

Bent Shape (2 bonded, 2 lone pairs)

A molecular geometry with 2 atoms bonded to a central atom and 2 lone pairs, resulting in a bond angle of $<<109.5^\circ$

Trigonal Planar Shape

A molecular geometry with 3 atoms bonded to a central atom and 0 lone pairs, yielding a bond angle of $120^\circ$

Trigonal Pyramidal Shape

A molecular geometry with 3 atoms bonded to a central atom and 1 lone pair, yielding a bond angle of $<109.5^\circ$

Tetrahedral Shape

A molecular geometry with 4 atoms bonded to a central atom and 0 lone pairs, giving a bond angle of $109.5^\circ$

Methane ($CH_4$) Structure

A nonpolar hydrocarbon Lewis structure consisting of a central carbon single-bonded to four hydrogen atoms