Water Concepts of Biology - Section 2.2 Flashcards

These vocabulary flashcards cover the properties of water, its role as a solvent, the concept of pH, and the function of buffers based on Section 2.2 of Concepts of Biology.

Polar Covalent Bonds

The type of bonds formed between hydrogen and oxygen atoms within water molecules where shared electrons spend more time associated with the oxygen atom.

Hydrophilic

Meaning "water-loving," this refers to substances that readily form hydrogen bonds with water and can dissolve in it.

Hydrophobic

Meaning "water-fearing," this refers to nonpolar compounds like oils and fats that do not readily form hydrogen bonds and will not dissolve in water.

Evaporation

The process where individual water molecules are released at the surface of a liquid, such as skin or leaves, which requires an input of energy and results in cooling.

Solvent

A substance capable of dissolving another substance.

Sphere of Hydration

A layer of water molecules that surrounds charged particles, also referred to as a hydration shell, which keeps particles separated or dispersed in water.

Dissociation

The process where ionic compounds, such as table salt ($NaCl$), separate into individual ions when mixed in water.

Cohesion

The property where water molecules are attracted to each other due to hydrogen bonding, keeping the molecules together at the liquid-air interface.

Surface Tension

The capacity of a substance to withstand rupture when placed under tension or stress.

Adhesion

The attraction between water molecules and other molecules, such as when water "climbs" up a straw.

pH Scale

A scale ranging from $0$ to $14$ that measures the concentration of hydrogen ions in a substance, where $7.0$ is neutral.

Litmus Paper

Paper treated with a natural water-soluble dye used as a pH indicator to test the acidity or basicity of a solution.

Acids

Substances that provide hydrogen ions ($H^+$) and lower pH.

Bases

Substances that provide hydroxide ions ($OH^-$) and raise pH.

Buffers

Substances that readily absorb excess $H^+$ or $OH^-$, maintaining the body's pH within a narrow window (typically $7.2$ to $7.6$).

Carbonic Acid ($H_2CO_3$) and Bicarbonate ($HCO_3^-$)

Components of a prominent buffer system in the human body that maintains proper pH levels.