AP Bio Chap 3

Polar covalent bond

A type of bond where electrons are shared unequally, creating a molecule with partial charges, such as in water.

Hydrogen bond

A weak bond formed between a hydrogen atom and an electronegative atom, such as oxygen in water.

Cohesion

The property of water that allows it to stick to itself, resulting from hydrogen bonding.

Adhesion

The property of water that allows it to stick to other substances.

Kinetic energy

The energy of motion, which is responsible for thermal energy.

Thermal energy

Kinetic energy associated with the random motion of molecules.

Temperature

The average kinetic energy of molecules in a substance.

Heat

The thermal energy transferred between objects due to a temperature difference.

Specific heat

The amount of heat required to change the temperature of a unit mass of a substance by 1 degree Celsius; water has a high specific heat.

Evaporation

The process where liquid turns into gas.

Heat of vaporization

The amount of heat required to convert a unit mass of a liquid into vapor without change in temperature.

Ice density

Ice is less dense than liquid water due to its ordered hydrogen bond structure.

Solution

A homogeneous mixture where a solute is dissolved in a solvent.

Solvent

The substance that dissolves a solute, usually present in larger amounts.

Solute

The substance that is dissolved in a solvent.

Hydration shell

The cluster of water molecules surrounding a solute or ions in a solution.

Hydrophilic

Substances that are attracted to water.

Hydrophobic

Substances that are not attracted to water.

Avogadro's number

The number of molecules in one mole, approximately $6.02 \times 10^{23}$.

Molarity

A measure of concentration; moles of solute divided by liters of solution.

Dissociation of water

The process where water molecules split into hydronium (H₃O⁺) and hydroxide (OH⁻) ions.

Acid

A substance that increases the concentration of H⁺ ions in a solution.

Base

A substance that decreases the concentration of H⁺ ions in a solution.

pH

The negative logarithm of the hydrogen ion concentration, indicating the acidity or basicity of a solution.

Buffer

A solution that minimizes changes in pH by neutralizing added acids or bases.