Intermolecular Attractions

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Intermolecular Forces Noun

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[in-ter-muh-lek-yuh-ler for-sez]

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Intermolecular Forces

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The various types of attractions between molecules, which are generally weaker than the ionic or covalent bonds within molecules.

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Example: This diagram shows the weak attraction (intermolecular force) between two separate molecules, contrasting it with the strong bond (intramolecular force) within a single molecule.

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Van der Waals Forces Noun

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[van der wawlz for-sez]

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Van der Waals Forces

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The weakest types of intermolecular attractions, which collectively include both dispersion forces and permanent dipole-dipole interactions.

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Example: This diagram shows how the random movement of electrons creates a temporary charge imbalance in one atom, which then induces an opposite imbalance in a nearby atom, causing a weak attraction between them.

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Dispersion Forces Noun

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[dis-pur-zhun for-sez]

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Dispersion Forces

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The weakest molecular interactions caused by the random motion of electrons creating temporary, induced dipoles in all molecules.

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Example: The image shows how a temporary, uneven spread of electrons in one molecule creates a weak, temporary magnet (dipole) that attracts a neighboring molecule.

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Polarize Verb

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[poh-luh-rahyz]

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Polarize

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To induce a temporary or permanent separation of electric charge in a molecule, creating oppositely charged ends or dipoles.

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Example: In a polar molecule like water, electrons are shared unevenly, creating a slightly negative end (pole) and a slightly positive end (pole).

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Temporary Dipole Noun

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[tem-puh-rer-ee dahy-pohl]

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Temporary Dipole

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A momentary, uneven distribution of electron charge in a molecule, creating a brief separation of positive and negative charge.

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Example: The random movement of electrons in a molecule creates a temporary, uneven charge (a dipole), which then attracts a neighboring molecule.

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Dipole Interactions Noun

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[dahy-pohl in-ter-ak-shunz]

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Dipole Interactions

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Intermolecular attractions that occur between the oppositely charged regions of adjacent permanent polar molecules.

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Example: This diagram shows two polar molecules attracting each other. The partially positive end (δ+) of one molecule is attracted to the partially negative end (δ-) of the other.

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Polar Molecule Noun

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[poh-ler mol-i-kyool]

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Polar Molecule

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A molecule that has permanent partial positive and partial negative ends due to an uneven distribution of bonding electrons.

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Example: This diagram shows a water molecule where electrons are shared unevenly, making the oxygen side slightly negative (-) and the hydrogen side slightly positive (+).

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Nonpolar Molecule Noun

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[non-poh-ler mol-i-kyool]

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Nonpolar Molecule

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A molecule in which electrons are distributed symmetrically, resulting in no permanent separation of charge or net dipole moment.

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Example: The symmetrical shape of a methane (CH₄) molecule causes electrons to be shared equally, so there are no positive or negative ends.

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Hydrogen Bonds Noun

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[hahy-druh-jen bondz]

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Hydrogen Bonds

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A strong dipole-dipole interaction where a hydrogen atom bonded to a highly electronegative atom is attracted to another nearby electronegative atom.

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Example: This diagram shows how a hydrogen bond is a weak attraction between a hydrogen atom on one water molecule and an oxygen atom on another.

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Electronegative Adjective

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[ih-lek-troh-neg-uh-tiv]

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Electronegative

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Describing the tendency of an atom to attract a shared pair of electrons towards itself in a chemical bond.

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Example: An oxygen atom has six electrons in its outer shell, making it strongly attract two more electrons to become stable, which is why it is electronegative.