Water and Aqueous Systems

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Electronegativity Noun

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

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Electronegativity

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The measure of the tendency of an atom to attract a bonding pair of electrons in a covalent bond.

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Example: The highly electronegative oxygen atom pulls electrons away from the hydrogen atoms, creating a partial negative charge on the oxygen and partial positive charges on the hydrogens.

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Polarity Noun

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[poh-lar-i-tee]

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Polarity

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A property of a molecule with a net dipole moment, resulting from the uneven distribution of electric charge.

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Example: A water molecule has polarity because the oxygen atom pulls electrons more strongly, giving it a slight negative charge (δ-) and the hydrogen atoms a slight positive charge (δ+).

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Hydrogen Bonding Noun

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[hy-druh-jen bon-ding]

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Hydrogen Bonding

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A strong intermolecular attraction between a partially positive hydrogen atom and a nearby highly electronegative atom like oxygen or nitrogen.

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Example: This diagram shows a hydrogen bond as the weak attraction connecting two separate water molecules, which is different from the stronger covalent bonds inside each molecule.

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Surface Tension Noun

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[sur-fis ten-shun]

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Surface Tension

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The inward force that minimizes the surface area of a liquid, causing it to behave as if covered by an elastic membrane.

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Example: Molecules inside a liquid are pulled equally in all directions, but molecules at the surface are pulled only inwards, creating a strong 'skin' effect.

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Surfactant Noun

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[sur-fak-tunt]

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Surfactant

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A substance that reduces the surface tension of a liquid, thereby increasing its spreading and wetting properties.

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Example: A surfactant molecule has a polar, hydrophilic (water-loving) head and a non-polar, hydrophobic (water-hating) tail, allowing it to interact with both water and oil.

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Aqueous Solution Noun

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[ey-kwee-uhs suh-loo-shun]

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Aqueous Solution

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A homogeneous mixture in which the solvent is water, created when a substance is dissolved in water.

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Example: This diagram shows a solution, where a substance (the solute) is evenly mixed into another substance (the solvent), like salt dissolved in water.

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Solvent Noun

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[sol-vunt]

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Solvent

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The dissolving medium in a solution; the substance in which a solute dissolves to form a homogeneous mixture.

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Example: This diagram shows that a solvent (blue particles) is the substance in a solution that dissolves the solute (pink particles).

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Solute Noun

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[sol-yoot]

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Solute

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The dissolved particles in a solution; the substance that is dissolved in a solvent to form a solution.

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Example: This diagram shows a sugar cube, the solute, which is the substance that gets dissolved in a liquid (the solvent) to form a solution.

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Solvation Noun

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[sol-vey-shun]

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Solvation

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The process by which solvent molecules surround and stabilize solute ions or molecules as a substance dissolves.

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Example: Polar water molecules surround and separate the positive (cations) and negative (anions) ions from a solid crystal, causing it to dissolve.

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Electrolyte Noun

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[ih-lek-truh-lahyt]

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Electrolyte

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A compound that conducts an electric current when dissolved in an aqueous solution or in the molten state.

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Example: An electrolyte, like salt dissolved in water, contains ions that allow it to conduct electricity and complete a circuit, causing the light bulb to glow.