chapter 2 ptB

Comprehensive vocabulary flashcards covering intermolecular attractions, the properties of water, acids and bases, types of mixtures, and biological macromolecules.

Intermolecular attractions

Weak chemical attractions between molecules that are important for maintaining the shape of complex molecules like DNA and proteins.

Hydrogen bond

A weak attraction between a partially positive hydrogen atom and a partially negative atom that forms between polar molecules.

Hydrophobic interactions

Interactions that occur when nonpolar molecules are placed in a polar substance; if occurring within parts of a large molecule, they are called intramolecular attractions.

Organic molecules

Molecules that contain carbon and are (or were) part of a living organism.

Inorganic molecules

Molecules that include water, salts, acids, and bases.

Water (H2O) Structure

A polar molecule composed of one oxygen atom with two partial negative charges bonded to two hydrogen atoms, each with a single partial positive charge.

Cohesion

The attraction between water molecules due to hydrogen bonding.

Surface tension

The inward pulling of cohesive forces at the surface of water; in the lungs, it is countered by surfactant to prevent sac collapse.

Adhesion

The attraction between water molecules and a substance other than water.

Specific heat

The amount of energy required to increase the temperature of $1\,g$ of a substance by $1^\circ\text{C}$. Water has an extremely high value due to the energy needed to break hydrogen bonds.

Heat of vaporization

The heat required to release molecules from a liquid phase into a gaseous phase for $1\,g$ of a substance; water’s high value allows sweating to cool the body.

Hydrophilic

Literal meaning "water-loving"; refers to substances such as polar molecules and ions that dissolve in water.

Hydration shell

The structure formed when water molecules surround a substance as it dissolves.

Nonelectrolytes

Substances like glucose and alcohol that dissolve in water but remain intact and do not conduct an electric current.

Electrolytes

Substances like $NaCl$ and $HCl$ that dissolve and dissociate in water, allowing them to conduct an electric current.

Hydrophobic exclusion

The process where cohesive water molecules "force out" nonpolar molecules, which are often transported in blood by carrier proteins.

Amphipathic molecules

Molecules that contain both polar (hydrophilic) and nonpolar (hydrophobic) regions, such as phospholipids.

Hydronium ion

The $H_3O^+$ ion formed when a hydrogen ion is transferred to a second water molecule during spontaneous dissociation.

Acid

A substance that dissociates in water to produce $H^+$ and an anion; also known as a proton donor.

Base

A substance that accepts $H^+$ when added to a solution; also known as a proton acceptor.

pH

A measure of the relative amount of $H^+$ in a solution, ranging from $0$ to $14$; it is the inverse of the log for a given $H^+$ concentration.

Neutralization

The process of returning an acidic or basic solution to a neutral state (pH $7$).

Buffers

Substances that help prevent pH changes by accepting $H^+$ from excess acid or donating $H^+$ to neutralize base, such as the carbonic acid and bicarbonate in blood.

Suspension

A water mixture with material larger than $1\,mm$ (e.g., blood cells in plasma) that settles if not in motion and scatters light.

Colloid

A water mixture with particles smaller than a suspension but larger than a solution (e.g., cytosol) that remain mixed and scatter light.

Solution

A homogeneous water mixture with material smaller than $1\,nm$ (e.g., salt water) that does not scatter light or settle.

Emulsion

A special category of colloid consisting of water and a nonpolar liquid, such as breast milk, which does not mix unless shaken.

Molarity

A measure of concentration expressed as moles of solute per liter of solution ($mol/L$), which can alter with temperature changes.

Molality

A measure of concentration expressed as moles of solute per kilogram of solvent ($mol/kg$), which does not change with temperature.

Mole

The amount of a substance containing $6.022 \times 10^{23}$ atoms, ions, or molecules; its mass in grams is equal to the atomic or molecular mass.

Biological macromolecules

Large organic molecules synthesized by the body that always contain carbon, hydrogen, and oxygen.

Polymers

Molecules made of repeating subunits called monomers, including carbohydrates, nucleic acids, and proteins.

Dehydration synthesis

A process occurring during biomolecule synthesis where one subunit loses $-H$ and another loses $-OH$, forming a new covalent bond and producing water.

Hydrolysis

A process occurring during biomolecule breakdown where water is used to add an $-H$ to one subunit and an $-OH$ to another.

Triglycerides

Lipids used for long-term energy storage, formed from one glycerol and three fatty acids.

Lipogenesis

The formation of triglycerides from glycerol and fatty acids when excess nutrients exist.

Steroids

Hydrocarbons arranged in a multiringed structure (four rings), including cholesterol, steroid hormones, and bile salts.

Eicosanoids

Modified 20-carbon fatty acids derived from arachidonic acid that act as local signaling molecules in the inflammatory response and nervous system.