CHAPTER 2: WATER THE SOLVENT

Polarity

The uneven distribution of charge within a molecule, resulting from differences in electronegativity between atoms.

Solubility in Water

Some chemicals dissolve in water due to water's polar nature and the type of intermolecular forces involved.

Oil and Water Separation

Oil and water separate into layers because oil is nonpolar and does not interact favorably with polar water molecules.

Unique Properties of Water

Water has interesting properties due to its molecular geometry and polarity, which influence living systems.

Acids

Substances that can donate protons (hydrogen ions) when dissolved in water.

Bases

Substances that can accept protons or donate hydroxide ions in a solution.

pH

A measure of the acidity or basicity of a solution, indicating the concentration of hydrogen ions present.

Importance of pH

Knowing the pH is essential for maintaining optimal conditions for biochemical reactions and processes.

Electronegativity

The tendency of an atom to attract electrons in a chemical bond, influencing molecular polarity.

Polar Bonds

Bonds with unequal sharing of electrons, resulting in partial positive and negative charges.

Nonpolar Bonds

Bonds with equal sharing of electrons, resulting in no charge separation.

Dipole Moment

A measure of how polar a molecule is, indicating the distribution of charges within it.

Dipoles

Molecules with positive and negative ends due to uneven charge distribution.

Solvent Properties of Water

Water's polarity allows it to dissolve ionic and polar compounds through electrostatic attractions.

Ionic Bonds

Strong bonds formed from the attraction between positive and negative ions.

Intermolecular Forces

Weaker interactions between molecules that hold them together in a substance.

Intramolecular Forces

Stronger forces within a molecule that hold its atoms together.

Salt Bridges

Electrostatic interactions in proteins formed by the attraction of charged groups.

Ion-Dipole Interactions

Occur when ions interact with polar molecules in a solution.

Van der Waals Forces

Weak interactions between molecules due to temporary charge fluctuations.

Dipole-Dipole Interactions

Occur between polar molecules with partial positive and negative ends.

Dipole-Induced Dipole Interactions

A permanent dipole induces a temporary dipole in a neighboring nonpolar molecule.

Electron Cloud

The region around an atomic nucleus where electrons are likely to be found.

Transient Dipole

A temporary separation of charge within a normally nonpolar molecule.

Electron Density

The probability of finding an electron in a specific region around an atom.

Hydrophobic

Substances that do not dissolve in water due to their nonpolar nature.

Hydrophobic Interactions

Occur between nonpolar molecules, leading to clustering to minimize water contact.

Amphipathic

Compounds with both hydrophilic and hydrophobic regions, interacting with both polar and nonpolar substances.

Hydrogen Bonds

Non-covalent interactions between a hydrogen atom and a highly electronegative atom.

Acid Strength

The ability of an acid to donate a proton when dissolved in water, with strong acids fully dissociating.

Acid Dissociation Constant (Ka)

A numerical value indicating the strength of an acid in a solvent.

Henderson-Hasselbalch Equation

A mathematical relationship between the pKa of an acid and the pH of a solution containing the acid and its conjugate base.